Enhancing Magnetic Properties of Bulk Anisotropic NdFBFe Composite Magnets by Applying PowderCoating

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微晶纤维素的极限聚合度的英文单词

微晶纤维素的极限聚合度的英文单词全文共3篇示例，供读者参考篇1The Limiting Degree of Polymerization of Microcrystalline CelluloseIntroductionMicrocrystalline cellulose is a renewable and sustainable material that is widely used in various industries such as pharmaceuticals, food, cosmetics, and textiles. One important property of microcrystalline cellulose is its degree of polymerization, which refers to the number of glucose units in the cellulose chain. The degree of polymerization of microcrystalline cellulose can have a significant impact on its physical and chemical properties, and therefore it is important to determine the limiting degree of polymerization of this material.Factors Affecting the Degree of PolymerizationThe degree of polymerization of microcrystalline cellulose can be influenced by various factors such as the source of cellulose, the method of extraction and purification, the conditions of hydrolysis, and the degree of crystallinity. Forexample, cellulose from different sources such as wood, cotton, or bamboo may have different degrees of polymerization due to differences in the cellulose structure. Similarly, the method of extraction and purification can also affect the degree of polymerization as impurities and processing conditions may impact the cellulose chain length.Methods for Determining the Limiting Degree of PolymerizationThere are several methods for determining the limiting degree of polymerization of microcrystalline cellulose. One common method is gel permeation chromatography (GPC), which separates cellulose chains based on their size and provides information on the distribution of chain lengths. Another method is viscometry, which measures the intrinsic viscosity of cellulose solutions and can be used to calculate the degree of polymerization. Additionally, techniques such as X-ray diffraction and solid-state NMR spectroscopy can provide information on the crystalline structure of cellulose and its impact on the degree of polymerization.Importance of Limiting Degree of PolymerizationThe limiting degree of polymerization of microcrystalline cellulose is important as it can affect the properties andperformance of products made from this material. For example, in pharmaceutical applications, the degree of polymerization can impact the flowability, compressibility, and disintegration properties of tablets made from microcrystalline cellulose. In food applications, the degree of polymerization can influence the texture, mouthfeel, and stability of products such as sauces, dressings, and baked goods. Therefore, understanding and controlling the limiting degree of polymerization of microcrystalline cellulose is essential for ensuring the quality and consistency of products.ConclusionIn conclusion, the limiting degree of polymerization of microcrystalline cellulose plays a crucial role in determining its properties and performance in various applications. Factors such as the source of cellulose, extraction and purification methods, and crystallinity can influence the degree of polymerization of this material. Methods such as GPC, viscometry, X-ray diffraction, and solid-state NMR spectroscopy can be used to determine the limiting degree of polymerization of microcrystalline cellulose. By understanding and controlling the degree of polymerization, manufacturers can optimize the performance of products and ensure consistency in quality.篇2Title: The Limit Aggregate Degree of Microcrystalline CelluloseIntroductionMicrocrystalline cellulose, also known as MCC, is a type of purified cellulose derived from natural wood pulp. It is widely used in pharmaceuticals, food products, and other industries as a non-toxic and biodegradable additive. One of the key characteristics of MCC is its aggregate degree, which refers to the extent to which individual cellulose particles are bound together. Understanding the limit aggregate degree of MCC is crucial for optimizing its properties and applications.Factors affecting aggregate degreeSeveral factors can influence the aggregate degree of microcrystalline cellulose. The primary factor is the manufacturing process used to produce MCC. Different processing techniques, such as acid hydrolysis or mechanical grinding, can result in varying degrees of aggregation in the final product. In addition, the particle size, shape, and surface properties of MCC particles can also impact their tendency toaggregate. For example, smaller particles tend to form tighter aggregates compared to larger particles.Measurement techniquesThere are several methods available for measuring the aggregate degree of microcrystalline cellulose. One common approach is dynamic light scattering, which can provide information about the size, distribution, and stability of MCC aggregates. Another widely used technique is electron microscopy, which allows for direct visualization of the structure of MCC particles and aggregates. Additionally, methods such as rheology and spectroscopy can be used to study the mechanical and chemical properties of MCC aggregates.Importance of limit aggregate degreeThe limit aggregate degree of microcrystalline cellulose is critical for controlling its behavior in various applications. For example, in pharmaceutical formulations, the degree of aggregation can affect the flow properties, compressibility, and disintegration of MCC-based tablets. In food products, the aggregate degree can impact the texture, stability, and mouthfeel of MCC-containing formulations. By understanding and optimizing the aggregate degree of MCC, manufacturerscan tailor its properties to meet specific requirements in different industries.ConclusionIn conclusion, the limit aggregate degree of microcrystalline cellulose is a key parameter that influences its performance in various applications. By studying the factors that affect aggregation, employing appropriate measurement techniques, and controlling the aggregate degree, manufacturers can optimize the properties of MCC for specific uses. Further research into the relationship between aggregate degree and the properties of MCC will continue to enhance the understanding and utilization of this versatile cellulose material.篇3Microcrystalline cellulose (MCC) is a widely used excipient in pharmaceutical formulations due to its unique properties such as high surface area, low density, and excellent compressibility. MCC is produced by acid hydrolysis of purified cellulose, resulting in a network of microcrystalline particles with a high degree of polymerization.Polymerization refers to the process of joining together monomers to form a polymer chain. In the case of cellulose,polymerization involves the repeated linking of glucose units to form long chains. The degree of polymerization (DP) of cellulose refers to the number of glucose units in each polymer chain. The higher the DP, the longer the cellulose chain and the larger the molecule size.The DP of MCC is typically in the range of 200-250, which is significantly lower than that of native cellulose. This low DP is achieved through the controlled hydrolysis process, which breaks down the cellulose chains into shorter, microcrystalline particles. The limited polymerization of MCC is essential for its functional properties in pharmaceutical applications.The low DP of MCC plays a crucial role in its compressibility and flow properties. The shorter polymer chains allow for tighter packing of the particles, resulting in higher bulk density and improved flow characteristics. The high surface area of MCC particles also facilitates better binding with active pharmaceutical ingredients, enhancing tablet hardness and disintegration.Furthermore, the low DP of MCC contributes to its excellent water absorption capacity and swelling behavior. The reduced polymerization allows for increased porosity within the MCC structure, providing more sites for water adsorption. Thisproperty is particularly advantageous in controlled-release formulations, where the gradual uptake of water helps regulate drug release.In summary, the limited polymerization of microcrystalline cellulose is a key factor in its unique properties and widespread use as a pharmaceutical excipient. The low DP of MCC enables optimal compressibility, flowability, water absorption, and binding capabilities, making it an indispensable ingredient in tablet formulations. Researchers continue to explore ways to control and optimize the polymerization of MCC to further enhance its performance in pharmaceutical applications.。

纳米材料与微型机器外文文献翻译、中英文翻译

外文资料Nanotechnology and Micro-machine原文(一):NanomaterialNanomaterials and nanotechnology have become a magic word in modern society.Nanomaterials represent today’s cutting edge in the development of novel advanced materials which promise tailor-made functionality and unheard applications in all key technologies. So nanomaterials are considered as a great potential in the 21th century because of their special properties in many fields such as optics, electronics, magnetics, mechanics, and chemistry. These unique properties are attractive for various high performance applications. Examples include wear resistant surfaces, low temperature sinterable high-strength ceramics, and magnetic nanocomposites. Nanostructures materials present great promises and opportunities for a new generation of materials with improved and marvelous properties.It is appropriate to begin with a brief introduction to the history of the subject. Nanomaterials are found in both biological systems and man-made structures. Nature has been using nanomaterials for millions of years,as Disckson has noted: “Life itself could be regarded as a nanophase system”.Examples in which nanostructured elements play a vital role are magnetotactic bacteria, ferritin, and molluscan teeth. Several species of aquatic bacteria use the earth’s magnetic field to orient thenselves. They are able to do this because they contain chains of nanosized, single-domain magnetite particles. Because they have established their orientation, they are able to swim down to nutriments and away from what is lethal to them ,oxygen. Another example of nanomaterials in nature is that herbivorous mollusks use teeth attached to a tonguelike organ, the radula, to scrape their food. These teeth have a complexstructure containing nanocrystalline needles. We can utilize biological templates formaking nanomaterials. Apoferritin has been used as a confined reaction environmentfor the synthesis of nanosized magnetite particles. Some scholars consider biologicalnanomaterials as model systems for developing technologically useful nanomaterials.Scientific work on this subject can be traced back over 100 years.In 1861 theBritish chemist Thomas Graham coined the term colloid to describe a solutioncontaining 1 to 100 nm diameter particles in suspension. Around the turn of thecentury, such famous scientists as Rayleigh, Maxwell, and Einstein studied colloids.In 1930 the Langmuir-Blodgett method for developing monolayer films wasdeveloped. By 1960 Uyeda had used electron microscopy and diffraction to studyindividual particles. At about the same time, arc, plasma, and chemical flame furnaceswere employed to prouduce submicron particles. Magnetic alloy particles for use inmagnetic tapes were produced in 1970.By 1980, studies were made on clusterscontaining fewer than 100 atoms .In 1985, a team led by Smalley and Kroto foundC clusters were unusually stable. In 1991, Lijima spectroscopic evidence that 60reported studies of graphitic carbon tube filaments.Research on nanomaterials has been stimulated by their technologicalapplications. The first technological uses of these materials were as catalysts andpigments. The large surface area to volume ratio increases the chemicalactivity.Because of this increased activity, there are significant cost advantages infabricating catalysts from nanomaterials. The peoperties of some single-phasematerials can be improved by preparing them as nanostructures. For example, thesintering temperature can be decreased and the plasticity increased on single-phase,structural ceramics by reducing the grain size to several nanometers. Multiphasenanostructured materials have displayed novel behavior resulting from the small sizeof he individual phases.Technologically useful properties of nanomaterials are not limited to theirstructural, chemical, or mechanical behavior. Multilayers represent examples ofmaterials in which one can modify of tune a property for a specific application bysensitively controlling the individual layer thickness. It was discovered that the resistance of Fe-Cr multilayered thin films exhibited large changes in an applied magnetic field of several tens of kOe.This effect was given the name giant magnetoresistance (GMR). More recently, suitably annealed magnetic multilayers have been developed that exhibit significant magnetoresistance effects even in fields as low as 5 to10 Oe (Oersted). This effect may prove to be of great technological importance for use in magnetic recording read heads.In microelectronics, the need for faster switching times and ever larger integration has motivated considerable effort to reduce the size of electronic components. Increasing the component density increases the difficulty of satisfying cooling requirements and reduces the allowable amount of energy released on switching between states. It would be ideal if the switching occurred with the motion of a single electron. One kind of single-electron device is based on the change in the Coulombic energy when an electron is added or removed from a particle. For a nanoparticle this enery change can be large enough that adding a single electron will effectively blocks the flow of other electrons. The use of Coulombic repulsion in this way is called Coulomb blockade.In addition to technology, nanomaterials are also interesting systems for basic scientific investigations .For example, small particles display deviations from bulk solid behavior such as reductios in the melting temperature and changes (usually reductions) in the lattice parameter. The changes n the lattice parameter observed for metal and semiconductor particles result from the effect of the surface free energy. Both the surface stress and surface free energy are caused by the reduced coordination of the surface atoms. By studying the size dependence of the properties of particles, it is possible to find the critical length scales at which particles behave essentially as bulk matter. Generally, the physical properties of a nanoparticle approach bulk values for particles containing more than a few hundred atoms.New techniques have been developed recently that have permitted researchers to produce larger quantities of other nanomaterials and to better characterize these materials.Each fabrication technique has its own set of advantages anddisadvantages.Generally it is best to produce nanoparticles with a narrow size distribution. In this regard, free jet expansion techniques permit the study of very small clusters, all containing the same number of atoms. It has the disadvantage of only producing a limited quantity of material.Another approach involves the production of pellets of nanostructured materials by first nucleating and growing nanoparticles in a supersaturated vapor and then using a cold finger to collect the nanoparticle. The nanoparticles are then consolidated under vacuum. Chemical techniques are very versatile in that they can be applied to nearly all materials (ceramics, semiconductors, and metals) and can usually produce a large amount of material. A difficulty with chemical processing is the need to find the proper chemical reactions and processing conditions for each material. Mechanical attrition, which can also produce a large amount of material, often makes less pure material. One problem common to all of these techniques is that nanoparticles often form micron-sized agglomerates. If this occurs, the properties of the material may be determined by the size of the agglomerate and not the size of the individual nanoparticles. For example, the size of the agglomerates may determine the void size in the consolidated nanostructured material.The ability to characterize nanomaterials has been increased greatly by the invention of the scanning tunneling microscope (STM) and other proximal probes such as the atomic force microscope (AFM), the magnetic force microscope, and the optical near-field microscope.SMT has been used to carefully place atoms on surfaces to write bits using a small number of atmos. It has also been employed to construct a circular arrangement of metal atoms on an insulating surface. Since electrons are confined to the circular path of metal atoms, it serves ad a quantum ‘corral’of atoms. This quantum corral was employed to measure the local electronic density of states of these circular metallic arrangements. By doing this, researchers were able to verify the quantum mechanical description of electrons confined in this way.Other new instruments and improvements of existing instruments are increasingly becoming important tools for characterizing surfaces of films, biological materials, and nanomaterials.The development of nanoindentors and the improvedability to interpret results from nanoindentation measurements have increased our ability to study the mechanical properties of nanostructured materials. Improved high-resolution electron microscopes and modeling of the electron microscope images have improved our knowledges of the structure of the the particles and the interphase region between particles in consolidated nanomaterials.Nanotechnology1. IntroductionWhat id nanotechnology? it is a term that entered into the general vocabulary only in the late 1970’s,mainly to describe the metrology associated with the development of X-ray,optical and other very precise components.We defined nanotechnology as the technology where dimensions and tolerances in the range 0.1～100nm(from the size of the atom to the wavelength of light) play a critical role.This definition is too all-embracing to be of practical value because it could include,for example,topics as diverse as X-ray crystallography ,atomic physics and indeed the whole of chemistry.So the field covered by nanotechnology is later narrowed down to manipulation and machining within the defined dimensional range(from 0.1nm to 100nm) by technological means,as opposed to those used by the craftsman,and thus excludes,for example,traditional forms of glass polishing.The technology relating to fine powders also comes under the general heading of nanotechnology,but we exclude observational techniques such as microscopy and various forms of surface analysis.Nanotechnology is an ‘enabling’ technology, in that it provides the basis for other technological developments,and it is also a ‘horizontal’or ‘cross-sectional’technology in that one technological may,with slight variations,be applicable in widely differing fields. A good example of this is thin-film technology,which is fundamental to electronics and optics.A wide range of materials are employed in devices such as computer and home entertainment peripherals, including magnetic disc reading heads,video cassette recorder spindles, optical disc stampers and ink jet nozzles.Optical and semiconductor components include laser gyroscope mirrors,diffraction gratings,X-ray optics,quantum-well devices.2. Materials technologyThe wide scope of nanotechnology is demonstrated in the materials field,where materials provide a means to an end and are not an end in themseleves. For example, in electronics,inhomogeneities in materials,on a very fine scale, set a limit to the nanometre-sized features that play an important part in semiconductor technology, and in a very different field, the finer the grain size of an adhesive, the thinner will be the adhesive layer, and the higher will be the bond strength.(1) Advantages of ultra-fine powders. In general, the mechanical, thermal, electrical and magnetic properties of ceramics, sintered metals and composites are often enhanced by reducing the grain or fiber size in the starting materials. Other properties such as strength, the ductile-brittle transition, transparency, dielectric coefficient and permeability can be enhanced either by the direct influence of an ultra-fine microstructure or by the advantages gained by mixing and bonding ultra-fine powders.Oter important advantages of fine powders are that when they are used in the manufacture of ceramics and sintered metals, their green (i.e, unfired) density can be greatly increased. As a consequence, both the defects in the final produce and the shrinkage on firing are reduced, thus minimizing the need for subsequent processing.(2)Applications of ultra-fine powders.Important applications include:Thin films and coatings----the smaller the particle size, the thinner the coating can beElectronic ceramics ----reduction in grain size results in reduced dielectric thicknessStrength-bearing ceramics----strength increases with decreasing grain sizeCutting tools----smaller grain size results in a finer cutting edge, which can enhance the surface finishImpact resistance----finer microstructure increases the toughness of high-temperature steelsCements----finer grain size yields better homogeneity and densityGas sensors----finer grain size gives increased sensitivityAdhesives----finer grain size gives thinner adhesive layer and higher bond strength3. Precision machining and materials processingA considerable overlap is emerging in the manufacturing methods employed in very different areas such as mechanical engineering, optics and electronics. Precision machining encompasses not only the traditional techniques such as turning, grinding, lapping and polishing refined to the nanometre level of precision, but also the application of ‘particle’ beams, ions, electrons and X-rays. Ion beams are capable of machining virtually any material and the most frequent applications of electrons and X-rays are found in the machining or modification of resist materials for lithographic purposes. The interaction of the beams with the resist material induces structural changes such as polymerization that alter the solubility of the irradiated areas.(1) Techniques1) Diamond turning. The large optics diamond-turning machine at the Lawrence Livermore National Laboratory represents a pinnacle of achievement in the field of ultra-precision machine tool engineering. This is a vertical-spindle machine with a face plate 1.6 m in diameter and a maximum tool height of 0.5m. Despite these large dimensions, machining accuracy for form is 27.5nm RMS and a surface roughness of 3nm is achievable, but is dependent both on the specimen material and cutting tool.(2) GrindingFixed Abrasive Grinding The term“fixed abrasive” denotes that a grinding wheel is employed in which the abrasive particles, such as diamond, cubic boron nitride or silicon carbide, are attached to the wheel by embedding them in a resin or a metal. The forces generated in grinding are higher than in diamond turning and usually machine tools are tailored for one or the other process. Some Japanese work is in the vanguard of precision grinding, and surface finishes of 2nm (peak-to-valley) have been obtained on single-crystal quartz samples using extremely stiff grinding machinesLoose Abrasive Grinding The most familiar loose abrasive grinding processes are lapping and polishing where the workpiece, which is often a hard material such asglass, is rubbed against a softer material, the lap or polisher, with abrasive slurry between the two surfaces. In many cases, the polishing process occurs as a result of the combined effects of mechanical and chemical interaction between the workpiece, slurry and polished.Loose abrasive grinding techniques can under appropriate conditions produce unrivalled accuracy both in form and surface finish when the workpiece is flat or spherical. Surface figures to a few nm and surface finishes bettering than 0.5nm may be achieved. The abrasive is in slurry and is directed locally towards the workpiece by the action of a non-contacting polyurethane ball spinning at high speed, and which replac es the cutting tool in the machine. This technique has been named “elastic emission machining” and has been used to good effect in the manufacture of an X-ray mirror having a figure accuracy of 10nm and a surface roughness of 0.5nm RMS.3）Thin-film production. The production of thin solid films, particularly for coating optical components, provides a good example of traditional nanotechnology. There is a long history of coating by chemical methods, electro-deposition, diode sputtering and vacuum evaporation, while triode and magnetron sputtering and ion-beam deposition are more recent in their wide application.Because of their importance in the production of semiconductor devices, epitaxial growth techniques are worth a special mention. Epitaxy is the growth of a thin crystalline layer on a single-crystal substrate, where the atoms in the growing layer mimic the disposition of the atoms in the substrate.The two main classes of epitaxy that have ben reviewed by Stringfellow (1982) are liquid-phase and vapour-phase epitaxy. The latter class includes molecular-beam epitaxy (MBE), which in essence, is highly controlled evaporation in ultra high vacuum. MBE may be used to grow high quality layered structures of semiconductors with mono-layer precision, and it is possible to exercise independent control over both the semiconductor band gap, by controlling the composition, and also the doping level. Pattern growth is possible through masks and on areas defined by electron-beam writing.4. ApplicationsThere is an all-pervading trend to higher precision and miniaturization, and to illustrate this a few applications will be briefly referred to in the fields of mechanical engineering,optics and electronics. It should be noted however, that the distinction between mechanical engineering and optics is becoming blurred, now that machine tools such as precision grinding machines and diamond-turning lathes are being used to produce optical components, often by personnel with a backgroud in mechanical engineering rather than optics. By a similar token mechanical engineering is also beginning to encroach on electronics particularly in the preparation of semiconductor substrates.(1) Mechanical engineeringOne of the earliest applications of diamond turning was the machining of aluminum substrates for computer memory discs, and accuracies are continuously being enhanced in order to improve storage capacity: surface finishes of 3nm are now being achieved. In the related technologies of optical data storage and retrieval, the toler ances of the critical dimensions of the disc and reading head are about 0.25 μm. The tolerances of the component parts of the machine tools used in their manufacture, i.e.the slideways and bearings, fall well within the nanotechnology range.Some precision components falling in the manufacturing tolerance band of 5～50nm include gauge blocks, diamond indenter tips, microtome blades, Winchester disc reading heads and ultra precision XY tables (Taniguchi 1986). Examples of precision cylindrical components in two very different fields, and which are made to tolerances of about 100 nm, are bearing for mechanical gyroscopes and spindles for video cassette recorders.The theoretical concept that brittle materials may be machined in a ductile mode has been known for some time. If this concept can be applied in practice it would be of significant practical importance because it would enable materials such as ceramics, glasses and silicon to be machined with minimal sub-surface damage, and could eliminate or substantially reduce the need for lapping and polishing.Typically, the conditions for ductile-mode machining require that the depth of cutis about 100 nm and that the normal force should fall in the range of 0.1～0.01N. These machining conditons can be realized only with extremely precise and stiff machine tools, such as the one described by Yoshioka et al (1985), and with which quartz has been ground to a surface roughness of 2 nm peak-to-valley. The significance of this experimental result is that it points the way to the direct grinding of optical components to an optical finish. The principle can be extended to other materials of significant commercial importance, such as ceramic turbine blades, which at present must be subjected to tedious surface finishing procedures to remove the structure-weakening cracks produced by the conventional grinding process.(2) OpticsIn some areas in optics manufacture there is a clear distinction between the technological approach and the traditional craftsman’s approach, particul arly where precision machine tools are employed. On the other hand, in lapping and polishing, there is a large grey area where the two approaches overlap. The large demand for infrared optics from the 1970s onwards could not be met by the traditional suppliers, and provided a stimulus for the development and application of diamond-turning machines to optic manufacture. The technology has now progressed and the surface figure and finishes that can be obtained span a substantial proportion of the nanotechnology range. Important applications of diamond-turned optics are in the manufacture of unconventionally shaped optics, for example axicons and more generelly, aspherics and particularly off-axis components. Such as paraboloids.The mass production(several million per annum) of the miniature aspheric lenses used in compact disc players and the associated lens moulds provides a good example of the merging of optics and precision engineering. The form accuracy must be better than 0.2μm and the surface roughness m ust be below 20 nm to meet the criterion for diffraction limited performance.(3) ElectronicsIn semiconductors, nanotechnology has long been a feature in the development of layers parallel to the substrate and in the substrate surface itself, and the need for precision is steadily increasing with the advent of layered semiconductor structures.About one quarter of the entire semiconductor physics community is now engaged in studying aspects of these structures. Normal to the layer surface, the structure is produced by lithography, and for research purposes ar least, nanometre-sized features are now being developed using X-ray and electron and ion-beam techniques.5. A look into the futureWith a little imagination, it is not difficult to conjure up visions of future developments in high technology, in whatever direction one cares to look. The following two examples illustrate how advances may take place both by novel applications and refinements of old technologies and by development of new ones.(1) Molecular electronicsLithography and thin-film technology are the key technologies that have made possible the continuing and relentless reduction in the size of integrated circuits, to increase both packing density and operational speed. Miniaturization has been achieved by engineering downwards from the macro to the micro scale. By simple extrapolation it will take approximately two decades for electronic switches to be reduced to molecular dimensions. The impact of molecular biology and genetic engineering has thus provided a stimulus to attempt to engineer upwards, starting with the concept that single molecules, each acting as an electronic device in their own right, might be assembled using biotechnology, to form molecular electronic devices or even biochip computers.Advances in molecular electronics by downward engineering from the macro to the micro scale are taking place over a wide front. One fruitful approach is by way of the Langmure-Biodgett (LB) film using a method first described by Blodgett (1935).A multi-layer LB structure consists of a sequence of organic monolayers made by repeatedly dipping a substrate into a trough containing the monolayer floating on a liquid (usually water), one layer being added at a time. The classical film forming materials were the fatty acids such as stearic acid and their salts. The late 1950s saw the first widespread and commercially important application of LB films in the field of X-ray spectroscopy (e.g, Henke 1964, 1965). The important properties of the films that were exploited in this application were the uniform thickness of each film, i.e.one molecule thick, and the range of thickness, say from 5to 15nm, which were available by changing the composition of the film material. Stacks of fifty or more films were formed on plane of curved substrates to form two-dimensional diffraction gratings for measuring the characteristic X-ray wavelengths of the elements of low atomic number for analytical purposes in instruments such as the electron probe of X-ray micro-analyzer.(2) Scanning tunneling engineeringIt was stated that observational techniques such as microscopy do mot, at least for the purposes of this article, fall within the domain of nanotechnology. However,it is now becoming apparent that scanning tunneling microscopy(STM) may provide the basis of a new technology, which we shall call scanning tunneling engineering.In the STM, a sharp stylus is positioned within a nanometre of the surface of the sample under investigation. A small voltage applied between the sample and the stylus will cause a current to foow through the thin intervening insulating medium (e.g.air, vacum, oxide layer). This is the tunneling electron current which is exponentially dependent on the sample-tip gap. If the sample is scanned in a planr parallel to ies surface and if the tunneling current is kept cnstant by adjusting the height of the stylus to maintain a constant gap, then the displacement of the stylus provides an accurate representation of the surface topographyu of the sample. It is relevant to the applications that will be discussed that individual atoms are easily resolved by the STM, that the stylus tip may be as small as a single atom and that the tip can be positioned with sub-atomic dimensional accuracy with the aid of a piezoelectric transducer.The STM tip has demonstrated its ability to draw fine lines, which exhibit nanometre-sized struture, and hence may provide a new tool for nanometre lithography.The mode of action was not properly understood,but it was suspected that under the influence of the tip a conducting carbon line had been drawn as the result of polymerizing a hydrocarbon film, the process being assisted by the catalytic activity of the tungsten tip. By extrapolating their results the authors believed that it would be possible to deposit fine conducting lines on an insulating film. The tip would operatein a gaseous environment that contained the metal atoms in such a form that they could either be pre-adsorbed on the film or then be liberated from their ligands or they would form free radicals at the location of the tip and be transferred to the film by appropriate adjustment of the tip voltage.Feynman proposed that machine tools be used to make smaller machine tools which in turn would make still smaller ones, and so on all the way down to the atomic level. These machine tools would then operate via computer control in the nanometre domain, using high resolution electron microscopy for observation and control. STM technology has short-cricuired this rather cumbrous concept,but the potential applications and benefits remain.原文(二)Micro-machine1. IntroductionFrom the beginning, mankind seems instinctively to have desired large machines and small machines. That is, “large” and “small” in comp arison with human-scale. Machines larger than human are powerful allies in the battle against the fury of nature; smaller machines are loyal partners that do whatever they are told.If we compare the facility and technology of manufacturing larger machines, common sense tells us that the smaller machines are easier to make. Nevertheless, throughout the history of technology, larger machines have always stood ort. The size of the restored models of the water-mill invented by Vitruvius in the Roman Era, the windmill of the middle Ages, and the steam engine invented by Watt is overwhelming. On the other hand, smaller machined in history of technology are mostly tools. If smaller machines are easier to make, a variety of such machined should exist, but until modern times, no significant small machines existed except for guns and clocks.This fact may imply that smaller machines were actually more difficult to make. Of course, this does not mean simply that it was difficult to make a small machine; it means that it was difficult to invent a small machine that would be significant to human beings.。

采矿英语术语

abandoned drives [?'b?nd?nd] [draivs] 废巷道abrasion resistance [?'brei??n] [ri'zist?ns] 抗磨蚀能力abrasive [?'breisiv] 磨料absorbent [?b's?:b?nt] 吸收剂access ramp ['?kses] [r?mp] 出入沟，出入引道accessory minerals [?k'ses?ri] ['min?r?ls] 副矿物accidental explosion [,?ksi'dent?l] [ik'spl?u??n] 意外爆炸Accumulated losses 累计亏损Acid Mine Drainage 矿山酸性废水Acidic run-off water from mine waste dumps and mill tailings ponds containing sulphide minerals. Also refers to ground water pumped to surface from mines.acid mine water ['?sid] [main] ['w?:t?] 酸性矿水acid resistant ['?sid] [ri'zist?nt] 耐酸的acid rock ['?sid] [r?k] 酸性岩acidite ['?sidait] 酸性岩acidulation 酸化acquirer投资主体Acquisition premium 收购溢价activated charcoal ['?ktiveitid] ['t?ɑ:k?ul] 活性煤activator ['?ktiveit?] 活化剂adamic earth ['?d?mik] [?:θ] 红粘土additive ['?ditiv] 添加剂adhere [?d'hi?] 粘着adhesion force [?d'hi:??n] [f?:s] 粘附力Adit ['?dit] 平硐An opening driven horizontally into the side of a mountain or hill for providing access to a mineral deposit.adit collar ['?dit] ['k?l?] 平硐口adit cut mining ['?dit] [k?t] ['maini?] 平硐开采adjustable prop [?'d??st?bl] [pr?p] 伸缩式支柱Administration and Corporate expenses行政管理及公司费用Administrative expenses 管理费用adobe blasting [?'d?ubi] ['blɑ:sti?] 裸露装药爆破adobe shot [?'d?ubi] [??t] 裸露装药爆破advancement [?d'vɑ:nsm?nt, ?d'v?ns-] 掘进advancing along the strike [?d'vɑ:nsi?] [?'l??] [straik] 沿走向掘进Aeromagnetic survey 航磁测绘A geophysical survey using a magnetometer aboard, or towed behind, an aircraft. AFC-The armored face conveyor.工作面皮带输送机Used on the coal face of an underground mine to protect the workers and convey the coal to the crusherAgate ['?ɡ?t] 玛瑙Agglomerate [?'ɡl?m?r?t, -reit, ?'ɡl?m?reit] 集块岩aggregate thickness ['?ɡriɡ?t, '?ɡriɡeit] ['θiknis] 总厚度Agitation .搅动，搅拌In metallurgy, the act or state of being stirred or shaken mechanically, sometimes accomplished by the introduction of compressed air.Air Crossing- [ε?] ['kr?:si?] 气流交汇点A place where return air and fresh cross over but are still divided.air flow [ε?] [fl?u] 气流air intake [ε?] ['inteik] 进气口air vent [ε?] [vent] 气孔,排气口Airborne survey 航测A survey made from an aircraft to obtain photographs, or measure magnetic properties, radioactivity, etc.airleg [ε?] [leɡ] 气腿式钻机，风动钻架Alloy 合金A compound of two or more metals.Alluvium 冲积层；冲积土Relatively recent deposits of sedimentary material laid down in river beds, flood plains, lakes, or at the base of mountain slopes. (adj. alluvial).Alteration 蚀变Any physical or chemical change in a rock or mineral subsequent to its der and more localised than metamorphism.Alunite ['?ljunait] 明矾石anchor bolts 固定螺栓Ancillary Equipment [?k'ses?ri] [i'kwipm?nt] 辅助设备ANFO 氨油炸药Acronym for ammonium nitrate and fuel oil, a mixture used as a blasting agent in many mines. angle of dip ['??ɡl] [dip] 倾角anisotropic [?，nais?u'tr?pik] .各向异性的Anomaly 异常状态Any departure from the norm which may indicate the presence of mineralisation in the underlying bedrock.anthracite ['?nθr?sait] 无烟煤A hard, black coal containing a high percentage of fixed carbon and a low percentage of volatile matter.anticline ['?ntiklain] 背斜An arch or fold in layers of rock shaped like the crest of a wave.anticlinorium [,?ntiklai'n?:ri?m] 复背斜asbestos [?z'best?s] 石棉asphalt ['?sf?lt] 沥青asphyxia [?s'fiksi?], suffocation [,s?f?'kei??n], gassing ['ɡ?si?] 窒息Assay 化验；分析；鉴定，测定A chemical test performed on a sample of ores or minerals to determine the amount of valuable metals contained.Assay Foot 化验尺度(metre, inch,centimetre)Assessment Work 例行评估工作The amount of work, specified by mining law that must be performed each year in order to retain legal control of mining claims.Asset classified as held for sale供出售资产associate bed [?'s?u?i,eitid] [bed] 伴生层attributable to the owners of the parent entity归属母公司的auger drill ['?:ɡ?] [dril] 螺旋钻auger mining ['?:ɡ?] ['maini?] 螺旋钻采矿法augite ['?:d?ait] 辉石autoclave ['?:t?kleiv]: 高压灭菌器a closed strong vessel for conducting chemical reactions under high pressure and temperature.Autogenous Grinding 自磨The process of grinding ore in a rotating cylinder using large pieces of the ore instead of conventional steel balls or rods.Back [b?k] 巷道顶部The back is the roof or overhead surface of an underground opening.back fill [b?k] [fil] : 采空区充填Waste material used to fill the void created by mining an orebodybackfill cure ['b?kfil] [kju?] 回填物凝固Backhoe [b?kh?u] 反铲挖土机Backwardation (证券)交割延期(费)。

压力对CrSi2弹性及弹性各向异性影响的研究

压力对 CrSi2弹性及弹性各向异性影响的研究摘要：本文采用密度泛函理论计算了压力下CrSi2的声子谱、电子结构、弹性常数和弹性各向异性。

结果表明，CrSi2的晶体结构参数随着压力的增加而减小。

声子色散曲线在不同外加压力下没有出现虚频，说明它们都是动力稳定的。

弹性常数也符合Born准则，表明机械学稳定性。

CrSi2的弹性常数、体积模量、剪切模量、杨氏模量、泊松比和B/G都随压力的增加而增加，表明适当的外界压力可以加强CrSi2的延展性，从而让其在工业应用上有望成为具有良好前景的可塑性金属合金的备选材料。

热容量随着压力的增大而轻微的减小。

关键词：密度泛函理论；弹性性能；各向异性1.引言随着科技的发展，现代工业对材料的强度与延展性的要求逐步提升，过渡金属铬化物因其熔化温度高、化学稳定性良好、热导率高、优益的耐高温抗氧化的性能以及相对较低的密度，令其有望作用于高温结构[1-3]，这也是近几年的研究热点之一。

CrSi2可采用自蔓延高温合成法[4]和水冷铜模激光炉制备[5]。

CrSi2在室温下具有较低的断裂韧性，在高温(>1200℃)下强度和蠕变抗力有限，但是压力对于弹性各向异性的影响力尚不清楚[6]。

弹性性能与材料的热容量、热膨胀系数等基本性能有着密切的联系。

这些特征可以通过第一性原理[7]方法得到。

在以往的文献中，许多研究者在运用实验测量和密度泛函理论计算相互使用的方法来研究CrSi2的晶体结构、力学性能、电子结构、光学性质[6,7,8,9]。

为更好地理解压力下CrSi2 的弹性各向异性从而在高压环境中应用是极为重要的。

本文系统地研究了CrSi2在高压下的结构、声子谱、弹性性能及弹性各向异性，以期探索外界压力对CrSi2弹性性能及弹性各向异性的影响，从而开发设计出具有抗压力的高温合金材料。

2计算方法本文基于密度泛函理论中的赝势平面波的第一性原理方法，采用剑桥系列总能量包(CASTEP)代码[10-14]进行模拟计算。

(2021年整理)材料专业常用术语英语单词表

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Unit 1property （材料的）性质heat treatment 热处理metal 金属glass 玻璃plastics 塑料fiber 纤维electronic devices 电子器件component 组元，组分semiconducting materials 半导体材料materials science and engineering 材料科学与工程materials science 材料科学materials engineering 材料工程materials scientist 材料科学家materials engineer 材料工程师synthesize 合成synthesissubatomic structure 亚原子结构electron 电子atom 原子nuclei 原子核nucleusmolecule 分子microscopic 微观的microscope 显微镜naked eye 裸眼macroscopic 宏观的specimen 试样deformation 变形polished 抛光的reflect 反射magnitude 量级solid materials 固体材料mechanical properties 力学性质force 力elastic modulus 弹性模量strength 强度electrical properties 电学性质electrical conductivity 导电性dielectric constant 介电常数electric field 电场thermal behavior 热学行为heat capacity 热容thermal conductivity 热传导(导热性）magnetic properties 磁学性质magnetic field 磁场optical properties 光学性质electromagnetic radiation 电磁辐射light radiation 光辐射index of refraction 折射率reflectivity 反射率deteriorative characteristics 劣化特性processing 加工performance 性能linear 线性的integrated circuit chip 集成电路芯片strength 强度ductility 延展性deterioration 恶化，劣化mechanical strength 机械强度elevated temperature 高温corrosive 腐蚀性的fabrication 制造Unit 2chemical makeup 化学组成atomic structure 原子结构advanced materials 先进材料high-technology 高技术smart materials 智能材料nanoengineered materials 纳米工程材料metallic materials 金属材料nonlocalized electrons 游离电子conductor 导体electricity 电heat 热transparent 透明的visible light 可见光polished 抛光的surface 表面lustrous 有光泽的aluminum 铝silicon 硅alumina 氧化铝silica 二氧化硅oxide 氧化物carbide 碳化物nitride 氮化物dioxide 二氧化物clay minerals 黏土矿物porcelain 瓷器cement 水泥mechanical behavior 力学行为ceramic materials 陶瓷材料stiffness 劲度strength 强度hard 坚硬brittle 脆的fracture 破裂insulative 绝缘的resistant 耐……的resistance 耐力，阻力，电阻molecular structures 分子结构chain-like 链状backbone 骨架carbon atoms 碳原子low densities 低密度mechanical characteristics 力学特性inert 隋性synthetic (人工）合成的fiberglass 玻璃纤维polymeric 聚合物的epoxy 环氧树脂polyester 聚酯纤维carbon fiber—reinforced polymer composite 碳纤维增强聚合物复合材料glass fiber-reinforced materials 玻璃纤维增强材料high-strength， low-density structural materials 高强度低密度结构材料solar cell 太阳能电池hydrogen fuel cell 氢燃料电池catalyst 催化剂nonrenewable resource 不可再生资源Unit 3periodic table （元素)周期表atomic structure 原子结构magnetic 磁学的optical 光学的microstructure 微观结构macrostructure 宏观结构positively charged nucleus 带正电的原子核atomic number 原子序数proton 质子atomic weight 原子量neutron 中子negatively charged electrons 带负电的电子shell 壳层magnesium 镁chemical bonds 化学键partially-filled electron shells 未满电子壳层bond 成键metallic bond 金属键nonmetal atoms 非金属原子covalent bond 共价键ionic bond 离子键Unit 4physical properties 物理性质chemical properties 化学性质flammability 易燃性corrosion 腐蚀oxidation 氧化oxidation resistance 抗氧化性vapor (vapour）蒸汽，蒸气,汽melt 熔化solidify 凝固vaporize 汽化,蒸发condense 凝聚sublime 升华state 态plasma 等离子体phase transformation temperatures 相变温度density 密度specific gravity 比重thermal conductivity 热导linear coefficient of thermal expansion 线性热膨胀系数electrical conductivity and resistivity 电导和电阻corrosion resistance 抗腐蚀性magnetic permeability 磁导率phase transformations 相变phase transitions 相变crystal forms 晶型melting point 熔点boiling point 沸腾点vapor pressure 蒸气压atm 大气压glass transition temperature 玻璃化转变温度mass 质量volume 体积per unit of volume 每单位体积the acceleration of gravity 重力加速度temperature dependent 随温度而变的，与温度有关的grams/cubic centimeter 克每立方厘米kilograms/cubic meter 千克每立方米grams/milliliter 克每毫升grams/liter 克每升pounds per cubic inch 磅每立方英寸pounds per cubic foot 磅每立方英尺alcohol 酒精benzene 苯magnetize 磁化magnetic induction 磁感应强度magnetic field intensity 磁场强度constant 常数vacuum 真空magnetic flux density 磁通密度diamagnetic 反磁性的factor 因数paramagnetic 顺磁性的ferromagnetic 铁磁性的non-ferrous metals 非铁金属，有色金属brass 黄铜ferrous 含铁的ferrous metals 含铁金属,黑色金属relative permeability 相对磁导率transformer 变压器，变换器eddy current probe 涡流探针Unit 5hardness 硬度impact resistance 耐冲击性fracture toughness 断裂韧度,断裂韧性structural materials 结构材料anisotropic 各向异性orientation 取向texture 织构fiber reinforcement 纤维增强longitudinal 纵向transverse direction 横向short transverse direction 短横向a function of temperature 温度的函数，温度条件room temperature 室温elongation 伸长率tension 张力，拉力compression 压缩bending 弯曲shear 剪切torsion 扭转static loading 静负荷dynamic loading 动态载荷cyclic loading 循环载荷，周期载荷cross-sectional area 横截面stress 应力stress distribution 应力分布strain 应变engineering strain 工程应变perpendicular 垂直normal axis 垂直轴elastic deformation 弹性形变plastic deformation 塑性形变quality control 质量控制nondestructive tests 无损检测tensile property 抗张性能，拉伸性能Unit 6lattice 晶格positive ions 正离子a cloud of delocalized electrons 离域电子云ionization 电离,离子化metalloid 准金属，类金属nonmetal 非金属diagonal line 对角线polonium 钋semi—metal 半金属lower left 左下方upper right 右上方conduction band 导带valence band 价带electronic structure 电子结构synthetic materials （人工）合成材料oxygen 氧oxide 氧化物rust 生锈potassium 钾alkali metals 碱金属alkaline earth metals 碱土金属volatile 活泼的transition metals 过渡金属oxidize 氧化barrier layer 阻挡层basic 碱性的acidic 酸性的electrochemical series 电化序electrochemical cell 电化电池cleave 解理，劈开elemental 元素的，单质的metallic form 金属形态tightly-packed crystal lattice 密排晶格，密堆积晶格atomic radius 原子半径nuclear charge 核电荷number of bonding orbitals 成键轨道数overlap of orbital energies 轨道能重叠crystal form 晶型planes of atoms 原子面a gas of nearly free electrons 近自由电子气free electron model 自由电子模型an electron gas 电子气band structure 能带结构binding energy 键能positive potential 正势periodic potential 周期性势能band gap 能隙Brillouin zone 布里渊区nearly-free electron model 近自由电子模型solid solution 固溶体pure metals 纯金属duralumin 硬铝，杜拉铝Unit 9purification 提纯，净化raw materials 原材料discrete 离散的,分散的iodine 碘long—chain 长链alkane 烷烃,链烃oxide 氧化物nitride 氮化物carbide 碳化物diamond 金刚石graphite 石墨inorganic 无机的mixed ionic—covalent bonding 离子-共价混合键constituent atoms 组成原子conduction mechanism 传导机制phonon 声子photon 光子sapphire 蓝宝石visible light 可见光computer-assisted process control 计算机辅助过程控制solid—oxide fuel cell 固体氧化物燃料电池spark plug insulator 火花塞绝缘材料capacitor 电容electrode 电极electrolyte 电解质electron microscope 电子显微镜surface analytical methods 表面分析方法Unit 12macromolecule 高分子repeating structural units 重复结构单元covalent bond 共价键polymer chemistry 高分子化学polymer physics 高分子物理polymer science 高分子科学molecular structure 分子结构molecular weights 分子量long chains 长链chain—like structure 链状结构monomer 单体plastics 塑料rubbers 橡胶thermoplastic 热塑性thermoset 热固性vulcanized rubbers 硫化橡胶thermoplastic elastomer 热塑弹性体natural rubbers 天然橡胶synthetic rubbers 合成橡胶thermoplastic 热塑性thermoset 热固性resin 树脂polyethylene 聚乙烯polypropylene 聚丙烯polystyrene 聚苯乙烯polyvinyl—chloride 聚氯乙烯polyvinyl 聚乙烯的chloride 氯化物polyester 聚酯polyurethane 聚氨酯polycarbonate 聚碳酸酯nylon 尼龙acrylics 丙烯酸树脂acrylonitrile-butadiene—styrene ABS树脂polymerization 聚合（作用）condensation polymerization 缩聚addition polymerization 加聚homopolymer 均聚物copolymer 共聚物chemical modification 化学改性terminology 术语nomenclature 命名法chemist 化学家the Noble Prize in Chemistry 诺贝尔化学奖catalyst 催化剂atomic force microscope 原子力显微镜（AFM） Unit 15composite 复合材料multiphase 多相bulk phase 体相matrix 基体matrix material 基质材料reinforcement 增强体reinforcing phase 增强相reinforcing material 加强材料metal—matrix composite 金属基复合材料ceramic—matrix composite 陶瓷基复合材料resin—matrix composite 树脂基复合材料strengthening mechanism 增强机理dispersion strengthened composite 弥散强化复合材料particle reinforced composites 颗粒增强复合材料fiber—reinforced composites 纤维增强复合材料Unit 18nanotechnology 纳米技术nanostructured materials 纳米结构材料nanometer 纳米nanoscale 纳米尺度nanoparticle 纳米颗粒nanotube 纳米管nanowire 纳米线nanorod 纳米棒nanoonion 纳米葱nanobulb 纳米泡fullerene 富勒烯size parameters 尺寸参数size effect 尺寸效应critical length 临界长度mesoscopic 介观的quantum mechanics 量子力学quantum effects 量子效应surface area per unit mass 单位质量的表面积surface physics and chemistry 表面物理化学substrate 衬底，基底graphene 石墨烯chemical analysis 化学分析chemical composition 化学成分analytical techniques 分析技术scanning tunneling microscope 扫描隧道显微镜spatial resolution 空间分辨率de Brogile wavelength 德布罗意波长mean free path of electrons （电子)平均自由程quantum dot 量子点band gap 带隙continuous density of states 连续态密度discrete energy level 离散能级absorption 吸收infrared 红外ultraviolet 紫外visible 可见quantum confinement （effect) 量子限域效应quantum well 量子势阱optoelectronic device 光电子器件energy spectrum 能谱electron mean free path 电子平均自由程spin relaxation length 自旋弛豫长度Unit 21biomaterial 生物材料implant materials 植入材料biocompatibility 生物相容性in vivo 在活体内in vitro 在活体外organ transplant 器管移植calcium phosphate 磷酸钙hydroxyapatite 羟基磷灰石research and development 研发 R＆D Preparation & Characterizationprocessing techniques 加工技术casting 铸造rolling 轧制,压延welding 焊接ion implantation 离子注入thin—film deposition 薄膜沉积crystal growth 晶体生长sintering 烧结glassblowing 玻璃吹制analytical techniques 分析技术characterization techniques 表征技术electron microscopy 电子显微术X—ray diffraction X射线衍射calorimetry 量热法Rutherford backscattering 卢瑟福背散射neutron diffraction 中子衍射nuclear microscopy 核子微探针。

过渡金属及氧化物团簇结构、磁性、催化性质的第一性原理计算研究

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东南大学博士论文
东南大学博士论文
ＴｈｅｐｅｒｆｏｒｍａｎｃｅｏｆＰｔ／Ｃｕ（１１１）ｓｕｒｆａｃｅａｌｌｏｙｃａｔａｌｙｓｔｓｉｎｗａｔｅｒｇａｓｓｈｉｆｔｒｅａｃｔｉｏｎｗｉｔｈａｆｅｗＰｔａｔｏｍｓｄｏｐｉｎｇｉｎｔｈｅＣｕ（１１１）ｓｕｒｆａｃｅｗｅｒｅｅｘｐｌｏｒｅｄｂｙｕｓｉｎｇｓｐｉｎ—ｐｏｌａｒｉｚｅｄＤＦＴ．ＴｈｅＰｔ／Ｃｕ（１１１）ｓｕｒｆａｃｅａｌｌｏｙｃａｔａｌｙｓｔｓｎｏｔｏｎｌｙｒｅｍａｒｋａｂｌｙｄｅｃｒｅａｓｅｔｈｅａｄｓｏｒｐｔｉｏｎｅｎｅｒｇｙｏｆＣＯ，ｗｈｉｃｈＣａｎ
ｓｅｑｕｅｎｃｅｉｎｔｈｅｐｒｅｓｅｎｃｅｏｆＣＯ．
Ｔｈｅｅｌｅｃｔｒｏｎｉｃｐｒｏｐｅｒｔｉｅｓａｎｄｃｏｎｔｒｏｌｌｅｄｓｉｎｇｌｅａｔｏｍｃａｔａｌｙｓｉｓｏｆｉｓｏｍｏｒｐｈｏｕｓｓｕｂｓｔｉｔｕｔｅｄｂｉｍｅｔａｌｌｉｃ
ｏｘｉｄｅＴＭＶ３０１０（ＴＭ＝Ｓｃ，Ｔｉ，ＣｒａｎｄＣｏ）ａｎｄＶ４０１０ｗｅｒｅｓｔｕｄｉｅｄｗｉｔｈｉｎｔｈｅｆｒａｍｅｗｏｒｋｏｆａｇｒａｄｉｅｎｔ－ｃｏｒｒｅｃｔｅｄＤＦＴｃａｌｃｕｌａｔｉｏｎｓ．ＴｈｅｃｈａｒｇｅｄｃｌｕｓｔｅｒｓＶ４０９。１∥一ｓｈｏｗｄｉｆｆｅｒｅｎｔｅｌｅｃｔｒｏｎｉｃｐｒｏｐｅｒｔｙｆｒｏｍｉｓｏｅｌｅｃｔｒｏｎｉｃｓｕｂｓｆｉｔｕｔｉｏｎｂｉｍｅｔａｌｌｉｃｏｘｉｄｅＴｉｖ３０９Ｊ０／ＣｒＶ３０９，１０ｃｌｕｓｔｅｒｓａｎｄｔｈｅｔｅｒｍｉｎａｌＴＭ

Electronholography

materialsElectron holographyWhat direction? Single or multidomains? Coupling between nanoparticles?Bulk samples: optical microscopy + colloidal suspension of ferro µPnanometric samples:Electron holography : sensitive to the phase changes of the electronic wave –resolution: 5 nm Electron holography—basics and applicationsHannes Lichte and Michael Lehmann Rep. Prog. Phys.71 (2008) 016102Electron Holography for the Study of Magnetic Nanomaterials John Meurig Thomas, Edward T. Simpson, Takeshi Kasama, and Rafal E. Dunin-BorkowskiAcc. Chem. Res.41, 665 (2008)Electrons = particles:F = –eE –e v ⊗BRelativistic effects:Electrons = wave:Relativistic effects:In vacuum: V=0 and A =0Ψ(r,t)= a exp (i (k 0.r –ωt)); E = h ωPossible thanks to field emission guns (spatial and energetic coherence)samplehologrambiprism wiresampleHologram writing Coherent beamSeparated in 2 beamsDeviation of beams for interferenceContrastField emission electron gunSample over half of the beamWire at + potential (biprism)Holographie électroniquevacuumHolographieélectronique reference hologramDiffractionby the wireElectron holographyWhat direction? Single or multidomains? Coupling between nanoparticles?Bulk samples: optical microscopy + colloidal suspension of ferro µPnanometric samples:Electron holography : sensitive to the phase changes of the electronic wave –resolution: 5 nm Electron holography—basics and applicationsHannes Lichte and Michael Lehmann Rep. Prog. Phys.71 (2008) 016102Electron Holography for the Study of Magnetic Nanomaterials John Meurig Thomas, Edward T. Simpson, Takeshi Kasama, and Rafal E. Dunin-BorkowskiAcc. Chem. Res.41, 665 (2008)Electrons = particles: Relativistic effects:Electrons = waveRelativistic effects:In vacuum: V=0 and A =0Ψ(r,t)= a exp (i (k 0.r –ωt)); E = h ωIn sample: V ≠0 and A ≠0p = kk = k e/ v : the electron velocityprincipe de l’holographie optiqueécriture :faisceau très cohérentréférenceéchantillonlecture : faisceau très cohérenthologrammeHolographieélectronique Optical holographyOptical holographyWriting ReadingE= (O+ R)(O+ R)*=OO* + RR* + OR* + RO*transmittancet= 1-A EU= t R= A[(C+D)R+ OD+ R2O*O+ RO*R]materialsmagnetic phase image of FeNi particles and scheme of corresponding magnetic configuration deduced fromcomparison with simulationscProfile of electric potential phaseMICROSCOPY RESEARCH AND TECHNIQUE 64:390 (2004)Electron Holography for the Study of MagneticNanomaterialsJohn Meurig Thomas, Edward T. Simpson, TakeshiKasama, and Rafal E. Dunin-Borkowski Electron holography+ +16.5 nm30.2 nma) TEM micrograph and b) size distribution (histogram) and dynamic light scattering(DLS)measurements (line) of iron oxide nanoparticles NC30with cubic-shaped morphology.a) TEM micrograph and b) size distribution (histogram) and dynamic light scattering(DLS)measurements (line) of iron oxide nanoparticles NC16with cubic-shaped morphology.Ferrite nanocubesHigh resolution TEM micrographs of cubic-shaped NC16nanoparticles Fourier transform related to the observed isolated nanoparticles.Electron Tomography in classical TEM longitudinal one, taken alongthe plane marked in red in b).global view 8kX wire @ 150V (out of interference zone )100 nm100 nmface1face2 : hol1 f2 c23hologrammes40kX fil 150V face 2face 1c u b e 2c u b e 3face 1face 2MIP= mean internal potential = ½+MAG= magnetic phase=½-magnetic cubes made of platelets on a non magnetic coreOFeO(AFM) coreFe3O4(FM) shellplain cubes2D STEM-HAADF image reconstruct the volume ofdirection indicated by the averaging the line profiles computed projection of c).side viewa bFlorea, Lucian Roiban, Ovidiu Ersenfor the Study of Magnetic NanomaterialsThomas, Edward T. Simpson, Takeshi Kasama, and41, 665 (2008)Possible thanks to field emission guns (spatial and energetic coherence)1 2。

纳米晶高性能永磁材料特邀论文

Journal of Magnetism and Magnetic Materials242–245(2002)1277–1283Invited paperNanocrystalline high performance permanent magnets O.Gutﬂeisch*,A.Bollero,A.Handstein,D.Hinz,A.Kirchner,A.Yan,K.-H.M.uller,L.SchultzInstitute of Solid State and Materials Research,IFW Dresden,P.O.Box270016,01171Dresden,GermanyAbstractRecent developments in nanocrystalline rare earth–transition metal magnets are reviewed and emphasis is placed on research work at IFW Dresden.Principal synthesis methods include high energy ball milling,melt spinning and hydrogen assisted methods such as reactive milling and hydrogenation-disproportionation-desorption-recombination. These techniques are applied to NdFeB-,PrFeB-and SmCo-type systems with the aim to produce high remanence magnets with high coercivity.Concepts of maximizing the energy density in nanostructured magnets by either inducing a texture via anisotropic HDDR or hot deformation or enhancing the remanence via magnetic exchange coupling are evaluated.r2002Elsevier Science B.V.All rights reserved.Keywords:Permanent magnets;Nanocrystalline materials;Exchange coupling;Texture;Hydrogen absorption1.IntroductionNanocrystalline materials,including those of mag-netic materials,have been at the centre of numerousR&D activities during the last decade because of theirparticular scientiﬁc and technological properties.In thecase of hard magnetic rare earth–transition metal(R–T)compounds,it is the grain size and the presence orabsence of intergranular phases which give rise tounusual magnetic properties because of surface/interfaceeffects different from those of bulk or microcrystallinerge coercivities can be obtained once thegrain size is below a certain threshold where thecrystallites become single domain.In most of the R–T-compounds discussed here,the critical single-domainparticle size d c is a fraction of a micron.Assuming idealized microstructures,three prototypesof NdFeB-type magnets can be distinguished on thebasis of the ternary phase diagram[1]:Type(I)israre earth rich and the individual crystallites are sepa-rated by a thin paramagnetic layer,the rare earth-richintergranular phase.This structure leads to a decouplingof the hard magnetic grains resulting in high coercivities.Type(II)is obtained using the stoichiometric R2Fe14Bcomposition and the hard magnetic grains are in directcontact with each other(‘single-phase exchange coupledmagnets’)[2].Type(III)nanocomposite magnets are Rdeﬁcient(i.e.,R concentrations o11.76at%)and thecoupling occurs between the R2Fe14B grains(to providehigh coercivity)and soft magnetic Fe3B or Fe rich grains(to provide high magnetisation;e.g.J sða2FeÞ¼2:16T).The exchange interaction between the grains of thedifferent phases leads to single-phase demagnetisationcurves despite a multi-phase microstructure providedgrain sizes are below a certain threshold and para-magnetic intergranular phases are absent[3–5].En-hanced remanences of the isotropic hard magneticmaterials,larger than those predicted by the Stoner-Wohlfarth theory[6]for systems of isotropicallyoriented,magnetically uniaxial,non-interacting singledomain particles where M r=M S p0:5;are the conse-quence.The development of melt-spun or rapidly quenchedNd–Fe–B magnets by Croat and Herbst[7]coincidedwith that of sintered magnets by Sagawa[8].Nanocrys-talline structures can also be synthesised by mechanical *Corresponding author.Tel.:+49-351-4659-664;fax+49-351-4659-781.E-mail address:o.gutﬂeisch@ifw-dresden.de(O.Gutﬂeisch).0304-8853/02/$-see front matter r2002Elsevier Science B.V.All rights reserved.PII:S0304-8853(01)00989-1alloying [9],intensive milling or hydrogenation dispro-portionation desorption and recombination (HDDR)processing [10,11].These nanostructures,provide energy barriers preserving the metastable,permanently magne-tised state.The resulting isotropic powders are most commonly used for the production of bonded magnets,where they are usually mixed with polymer resin and are then injection or compression moulded.Bonded mag-nets have the advantage of easily accomplished near net-shape processing,the avoidance of eddy-currents and good mechanical properties.The disadvantage being the dilution of magnetic properties due to the polymer binder.The randomly oriented grain structure results in magnetically isotropic magnets,with the remanent polarisation,J r ;and (BH )max limited to 0.5and 0.25,respectively,of the values obtainable for ideal micro-structures consisting of single domain grains and with full crystallographic alignment.Therefore various con-cepts have to be developed in order to increase remanence as shown in Fig.1.The three most relevant ways of maximising the energy density (BH )max are hot deformation [12,13],inducement of texture via ‘aniso-tropic’HDDR [14]or thirdly,remanence enhancement via exchange coupling [3,4].In summary,the task of transferring good intrinsic properties such as high values of Curie temperature (T C >500K),high saturation magnetisation (M s >1T)and high anisotropy ﬁeld,H A into useful extrinsic properties of nanocrystalline magnets such as coercive ﬁeld H C ;remanent magnetisation B r and maximum energy density (BH )max by appropriate processing is described in this paper.2.Maximising the energy density (BH)max 2.1.High energy ball millingAs a non-equilibrium processing technique,mechan-ical alloying circumvents,like rapid quenching,many limitations of conventional alloying and thus can be used for the preparation of metastable alloys.The mixing of the elements is achieved by an interdiffusional reaction,enabled by the formation of ultraﬁne layered composite particles during high energy ball milling.Depending on the thermodynamics of the alloy system,energy input and the mechanical workability of the starting powders,the alloying can take place during milling or during a subsequent heat treatment [9].A variation of this high energy ball milling technique is intensive milling,where an alloy is exposed to high energy ball milling rather than the elemental powders.Here,an example is given for the intensive milling of a Pr–Fe–B-based alloy.Pr 2Fe 14B-type alloys are compar-able in terms of their intrinsic magnetic properties [15]and phase relations with the advantage of a much lower spin reorientation temperature.An alloy with the nominal composition Pr 9Nd 3Dy 1Fe 72Co 8B 6.9Zr 0.1has been milled for 60h (leading to a type II magnet)and also with various amounts of Fe powder (leading to type III magnets)and subsequently annealed at 6001C for 30min.The partly amorphous structure after milling is illustrated in Fig.2.The Curie-temperature of the alloy is T C ¼3801C.The magnetic properties of various annealed powders are shown in Fig.3.Optimised valued for (BH )max were above 175kJ/m 3when adding 20–25wt%Fe (B r ¼1:18T and i H c ¼0:66T).A key issueFig.1.Flow chart illustrating the principal processing routes of high energy density magnets based on micro-and nano-crystalline powders.The right branch shows the three principal ways of maximizing the energy product (BH )max of nanocrystalline magnets.O.Gutﬂeisch et al./Journal of Magnetism and Magnetic Materials 242–245(2002)1277–12831278for the effectiveness of the exchange coupling and thus the degree of remanence enhancement is the develop-ment of a uniform nanoscale microstructure of hard and soft magnetic grains.This can be realised by micro-alloying using additions such as Zr and Co having grain growth inhibiting effects [16,17]or leading to a modiﬁcation of the tie lines in the phase diagram and thus changed volume fractions of the different phases [18].An effective coupling occurs when the soft regions with a small anisotropy are no bigger than a few times the exchange length l ex ;i.e.o 20nm and thus a complete coupling of the soft magnetic grain occurs.The crystal-lite size of the annealed sample was evaluated from the broadening of the X-ray diffraction peaks (see Fig.3)using the Williamson-Hall method [19]and it was found to be around 20nm.Remanence enhanced high energy density magnets,synthesised by melt spinning or ball milling techniques,are of great commercial interest because no magnetic alignment and less of the costly rare earth element arerequired and an improved corrosion behaviour can be expected.2.2.Rapid quenchingCurrently,rapidly quenched Nd–Fe–B forms the basis for almost the entire bonded magnet industry.The ﬂexibility of bonded Nd–Fe–B-type magnets in proces-sing,shape and magnetic properties and the highly stable nature of the ribbons contribute to its success in a fast growing permanent magnet market [20–22].De-pending on the wheel speed,ejection conditions and melt temperature substantial undercooling below the equili-brium freezing temperature and,consequently,a very high frequency of crystal nucleation are achieved (‘‘over-quenching’’).Lower wheel speeds can lead directly to nano-crystalline material (‘‘direct-quenching’’).The inset of Fig.4shows the DSC curves on ﬁrst heating of melt-spun Nd 15DyFe 75.9B 8Zr 0.1and Pr 15Dy-Fe 75.9B 8Zr 0.1alloys.XRD patterns of both melt-spun materials showed a partly amorphous structure which explains the presence of a second order thermodynamic phase transition around 3101C and 2951C,respectively,during ﬁrst heating corresponding to the Curie-tem-perature of the remaining R 2Fe 14B phase.A comparison of the onset of crystallization of both alloys prepared by this technique and by intensive milling showed lower values in the case of the latter method:5801C for the Nd-based alloy and 5301C for the Pr-based alloy whereas values of 6001C and 5751C,respectively,were obtained when using melt-spinning [23].Annealing of the melt-spun alloys at 6501C leads to the com-plete formation of the R 2Fe 14B phase achieving coerciv-ities as high as 2.7T for PrDyFeBZr and 2.37T for3035404550556065707580••600˚Cafter millingi n t e n s i t y (a .u .)2 theta (degree)Fig.2.XRD patterns of Pr 9Nd 3Dy 1Fe 72Co 8B 6.9Zr 0.1after 60h of intensive milling in argon and after annealing at 6001C for 30min.Intensity peaks of a –Fe ( )are indicated.-1.5-1.0-0.50.00.51.01.5P o l a r i s a t i o n J ( T )Applied field µ0H ( T )Fig.3.Hysteresis loops of intensively milled (with various amounts of Fe)and annealed Pr 9Nd 3Dy 1Fe 72Co 8B 6.9Zr 0.1.P o l a r i s a t i o n J ( T )Applied field µ0H ( T )Fig.4.Demagnetisation curves of melt-spun NdDyFeBZr and PrDyFeBZr materials annealed at 6501C for 10min (inset:DSC curves on ﬁrst heating (40K/min)of melt-spun NdDyFeBZr and PrDyFeBZr showing Curie temperature,T C ;and crystal-lization onset,T x ).O.Gutﬂeisch et al./Journal of Magnetism and Magnetic Materials 242–245(2002)1277–12831279NdDyFeBZr (see Fig.4).The room temperature aniso-tropy ﬁeld of Pr 2Fe 14B is around 25%larger than of its Nd counterpart,and the saturation magnetisation is only slightly lower.Melt-spun precipitation hardened Sm 2(Co,Cu,-Fe,Zr)17magnets have been produced using single roller melt-spinning at low velocity and their magnetic proper-ties in the as-spun state and after hardening are shown in Fig.5.Coercivity is developed only during the complex annealing treatment leading to the formation of a cellular structure (see inset in Fig.5)similar to that in sintered 2:17-type magnets.However,the resulting powder in this case is isotropic.It has been found that this type of material can show an abnormal temperature dependence of the coercivity [24]leading to excellent high temperature magnetic properties also reported for sintered magnets [25,26].Another interesting aspect is the production of magnetically anisotropic SmCo 5-type ribbons also using low wheel speeds [27]and a (BH )max of 146kJ/m 3was obtained for Sm 1.1Co 5[28].The c -axis of the crystallites after direct-quenching were found to be parallel to the longitudinal axis of the ribbon.This phenomenon is shown here for various Sm 2(Co)17-type alloys with the successive addition of Fe,Zr and Cu.XRD patterns of Fig.6show that the degree of texture decreases when adding Zr and Cu.This is illustrated by the weaker (110)and (200)and stronger (111)and (002)peaks for the Sm 2(Co,Cu,Fe,Zr)17alloy.2.3.Hydrogen assisted processingThe HDDR process is established as a processing technique for the production of highly coercive Nd 2Fe 14B [10,11]and Sm 2Fe 17N y magnets [29,30].A special type of powder suitable for bonded magnets is the anisotropic powder made by HDDR [14]which could close the gap in the market for high energyproduct bonded magnets.Very recently,excellent magnetic values of B r ¼1:38T,i H c ¼1122kA/m and (BH )max =342kJ/m 3have been obtained for NdFe-GaNbB using a process which controls the reaction rates during exothermic hydrogen absorption (dispro-portionation)and endothermic desorption (recombina-tion)by pressure adjustments [31,32].This multistage HDDR process is beneﬁcial to optimise remanence and coercivity without expensive additions such as Co.Strictly,HDDR does not lead to nanoscale (usually deﬁned as o 100nm)material,as the ﬁnal product resulting from the reversible,hydrogen-induced chemi-cal reaction shows typical grain sizes of around 300nm.The disproportionated state is certainly nanoscale and it is this intermediate product which should clarify the mechanism of the inducement of texture.Various models have been suggested and they have been detailed in a recent review [33].Intermediate boride phases have been linked with the transfer of the original cast grain orientation to that of the recombined 2-14-1-type grains in both,NdFeCoGaB [34]and NdFeB [35]alloys.The HRSEM micrograph in Fig.7shows the solid-dispro-portionated state of a Nd 16.2Fe 78.2B 5.6alloy.The eutectoid-type decomposition into NdH 27x rods of appr.20nm and Fe and a build-up of ﬁnely dispersed Fe 3B particles of 10–50nm diameter in the intercolony regions due to an ejection of this phase from the rod-like areas can be observed.The principal solid-disproportionation reactions of the R 2Fe 14B (with R=Nd or Pr)phases can be described as follows:R 2Fe 14B þð27x ÞH 2)2RH 27x þ11Fe þFe 3B )2RH 27x þ12Fe þFe 2B :ð1ÞIn the case of a Pr 13.7Fe 63.5Co 16.7Zr 0.1B 6alloy a new intermediate boride phase,Pr(Fe,Co)12B 6(R3m),has been found recently after solid-disproportionation[36]Fig.5.Hysteresis loops of as-spun and precipitation hardened (T h =11601C,1h,T a =8501C,20h,cooling to 4001C with 0.75K/min)Sm(Co 0.74Cu 0.12Fe 0.1Zr 0.04)7.5(inset:TEM bright ﬁeld image of the latter).3035404550556065707580Sm 2Co 17Sm 2(Co 0.9Fe 0.1)17Sm 2(Co 0.86Fe 0.1Zr 0.04)17Sm 2(Co 0.74Fe 0.1Cu 0.12Zr 0.04)17(201)(002)(111)(110)(200)I n t e n s i t y (a .u .)2 theta (degree)Fig.6.XRD patterns of as-spun (using a low wheel speed)Sm 2(Co)17-type alloys with the successive addition of Fe,Zr and Cu.O.Gutﬂeisch et al./Journal of Magnetism and Magnetic Materials 242–245(2002)1277–12831280and a high degree of texture has also been reported for this type of alloys after conventional processing [37].The application of the HDDR process to the Nd–Co–B or Sm–Co systems requires more severe hydrogena-tion conditions which is due to the higher thermo-dynamic stability of the R–Co phases against the disproportionation by hydrogen compared to those of the Nd 2Fe 14B and Sm 2Fe 17phases.Recently,it was shown that HDDR in thermodynamically stabilised compounds such as Sm 2Fe 16Ga,SmCo 5,Sm 2Co 17and Nd 2Co 14B is successful when using high hydrogen pressures [38]or reactive milling in hydrogen [39].In case of Sm 2Co 17,the latter mechanically activated gas-solid reaction leads to the disproportionation of the rhombohedral 2:17phase into Sm-hydride and FCC Co according to the following equation:Sm 2Co 17þð27x ÞH 232SmH 27x þ17Co :ð2ÞIntimate mixtures of R-hydride with grain sizes o 10nm and BCC Fe or FCC Co are obtained after reactive milling which is not possible when applying the conventional HDDR process [33].For SmCo-type alloys,the following desorption treatment at tempera-tures as low as 5001C leads to the recombination to the original structure either of CaCu 5and Th 2Zn 17type.In dependence on Sm content,milling parameters and desorption temperature additional phases are synthe-sised,partly of metastable character,such as the Sm 2Co 7phase.The recombined multiphase material exhibits grain sizes of the scale o 30nm (compare Fig.8)which makes an effective exchange coupling and thus rema-nence enhancement possible.Magnetically single phase demagnetisation loops are observed and a clear tendency of increased coercivity and decreased reman-cence with increasing Sm content is found [40].2.4.Hot deformationHot deformation-induced texturing of nano-grained materials is an option for producing fully dense,anisotropic magnets with maximised energy densities.A grain alignment along the c -axis of the tetragonal 2:14:1phase based on either Nd–Fe–B or Pr–Fe–B alloys perpendicular to the plastic ﬂow is achieved after high temperature compressive deformation [12,13].The production of a fully dense isotropic precursor at about 7251C is followed by placing this compact in an oversized die-cavity where die-upsetting is carried out at similar temperatures.After this second step,an anisotropic magnet is obtained with the alignment of the crystallographic c -axis parallel to the pressing direction.Alternatively,backward extrusion [41]can be carried out as a second step to produce near net-shape ring magnets which can show,especially for smaller dimensions,superior magnetic properties to sintered magnets.A radial preferential orientation is obtained,again with the c -axis alignment perpendicular to the material ﬂow.Small variations in the magnetic properties have been observed along the cross-section and along the axial direction of the ring magnets which were attributed to inhomogeneities in material ﬂow inherent to the deformation process [42].Additions of Co are used to improve the thermal stability and to increase the Curie-temperature in sintered NdFeB magnets.Simultaneously the coercivity is reduced,which again can be compensated by small additions of Ga.The same positive effect of Co and Ga was found in hot deformed NdFeB magnets,prepared from melt-spun material (MQU-F).The addition of Ga decreases melting point and viscosity of the Nd-rich grain boundary phase.This accelerates mass transfer through the liquid and improves the isolation of the grains leading to enhanced coercivities.TEM-EDX analysis showed a preferential solution of Ga intotheFig.8.TEM bright ﬁeld image of reactively milled and recombined Sm 2Co 17powder.Fig.7.Scanning electron microscopy image in the backscat-tered mode showing the rod-like structure of NdH 27x (A)and a –Fe (B)and ﬁnely dispersed Fe 3B (C)obtained after 15min of solid-disproportionation at 9001C.O.Gutﬂeisch et al./Journal of Magnetism and Magnetic Materials 242–245(2002)1277–12831281Nd-rich grain boundary phase,now a neodymium–iron–gallium phase.Ga reduces the surface energy of this phase resulting in smoothed grain boundaries and a more uniform distribution [43].Thus,lower deformation forces are required for hot deformation and higher B r material can be produced because of an increased volume fraction of the hard magnetic 2:14:1phase with a commensurate reduction in the non-ferromagnetic grain boundary material.Demagnetisation curves of hot pressed and die-upset melt-spun NdFeB-type powders are shown in Fig.9.As a comparison,hot pressed and die-upset intensively milled Pr 14.7Fe 77.3B 8.0powder is also included.The already mentioned much lower spin reorientation temperature make them attractive for low temperature applications such as superconducting bearings.Opti-mised deformation conditions were used for the production of MQ-type magnets [43]and remarkably higher coercivities were found in hot pressed and in hot deformed MQU-F magnets.A reduction in coercivity after die-upsetting can be observed which amounts to 25%in MQU-F magnets and to 40%in MQP-A.The higher coercivity in MQU-F magnets is due to the beneﬁcial effect of the additives resulting in smaller grains after hot deformation.A remanence of B r ¼1:3T and a (BH )max =326kJ/m 3were measured for the MQU-F die-upset magnet.The loop shape ((BH )max =307kJ/m 3)and the hot workability of the Pr 14.7Fe 77.3B 8.0die-upset magnet made from intensively milled powder are excellent and it can be expected that compositional modiﬁcations will improve the magnetic properties further.3.ConclusionsNowadays about 85%of the limit for the energy density (BH )max (based on the Nd 2Fe 14B phase)can beachieved in commercially produced sintered Nd–Fe–B grades [44,45].Coercivity values however,rarely exceed 20–30%of the anisotropy ﬁeld H A .Recent exciting developments include excellent anisotropic HDDR powders for polymer bonded magnets and SmCo-type magnets for application temperatures as high as 5501C.In terms of maximised energy densities,there is still a lot of scope for improvement for bonded and fully dense nanocrystalline magnets,especially considering multi-component systems.In this context,it is just to state that computational micromagnetism based on realistic mi-cro-and nano-structures and modelling of phase diagrams will be of increased importance in order to map the vast number of ternary,quaternary,etc.equilibrium and non-equilibrium phases.Novel proces-sing techniques and microalloying should allow more freedom for tailoring magnetic and non-magnetic properties of nanocrystalline high performance perma-nent magnets.AcknowledgementsThe support of parts of this work by the Deutsche Forschungsgemeinschaft (SFB 463),SfP (Science for Peace,Nato)and the EU (HITEMAG)is gratefully acknowledged.References[1]K.H.J.Buschow,in:K.H.J.Buschow (Ed.),Handbook ofMagnetic Materials,Vol.10,Elsevier Science,North Holland,Amsterdam,1997(Chapter 4).[2]G.B.Clemente,K.E.Keem,J.P.Bradley,J.Appl.Phys.64(1988)5299.[3]R.Coehoorn, D.B.Mooji,J.P.Duchateau,K.H.J.Buschow,J.Phys.49(C8)(1988)669.[4]E.F.Kneller,R.Hawig,IEEE Trans.Magn.27(1991)3588.[5]K.H.M .uller,D.Eckert,A.Handstein,M.Wolf,S.Wirth,L.L.M.Martinez,Proceedings of the Eighth International Symposium Magn.Anisotropy and Coercivity in RE-TM Alloys,Birmingham,UK,1994,p.179.[6]E.C.Stoner, E.P.Wohlfarth,Philos.Trans.R.Soc.London,Ser.A 240(1948)599.[7]J.J.Croat,J.F.Herbst,R.W.Lee,F.E.Pinkerton,J.Appl.Phys.55(1984)2078.[8]M.Sagawa,S.Fujimori,M.Togawa,Y.Matsuura,J.Appl.Phys.55(1984)2083.[9]L.Schultz,J.Wecker, E.Hellstern,J.Appl.Phys.61(1987)3583.[10]T.Takeshita,R.Nakayama,Proceedings of the 10thInternational Workshop on RE Magnets and their Appl.,Kyoto,Japan,1989,p.551.[11]P.J.McGuiness,X.J.Zhang,X.J.Yin,I.R.Harris,J.Less-Common Met.158(1990)379.[12]R.K.Mishra,R.W.Lee,Appl.Phys.Lett.48(1986)733.-3.0-2.5-2.0-1.5-1.0-0.50.00.00.20.40.60.81.01.21.4P o l a r i z a t i o n J (T )Applied field µ0H (T)Fig.9.Demagnetisation curves of hot pressed and die-upset melt-spun NdFeB-type and intensively milled PrFeB-type materials.O.Gutﬂeisch et al./Journal of Magnetism and Magnetic Materials 242–245(2002)1277–12831282[13]J.J.Croat,IEEE Trans.Magn.25(1989)3550.[14]T.Takeshita,R.Nakayama,12th International Workshopon RE Magnets and their Appl.,Canberra,1992,p.670.[15]S.Hirosawa,Y.Matsuura,H.Yamamoto,S.Fujimura,M.Sagawa,H.Yamauchi,J.Appl.Phys.59(1986)873.[16]V.Neu,U.Klement,R.Sch.a fer,J.Eckert,L.Schultz,Mater.Lett.26(1996)167.[17]H.A.Davies,J.Magn.Magn.Mater.157/158(1996)11.[18]N.Sano,T.Tomida,S.Hirosawa,M.Uehara,H.Kanekiyo,Mater.Sci.Eng.A250(1998)146.[19]G.K.Williamson,W.H.Hall,Acta Metall.1(1953)22.[20]V.Panchanathan,Proceedings of the16th InternationalWorkshop on RE Magnets and their Appl.,Sendai,Japan, 2000,p.431.[21]G.C.Hadjipanayis,W.Gong,J.Appl.Phys.64(1988)5589.[22]H.A.Davies,C.L.Harland,J.I.Betancourt,G.Menoza,MRS Symp.Proceedings‘Advanced Hard and Soft Magnets’,Vol.577,1999,p.27.[23]A.Bollero,A.Kirchner,O.Gutﬂeisch,K.H.M.uller,L.Schultz,IEEE Trans.Magn.37(2001)2483.[24]D.Goll,I.Kleinschroth,W.Sigle,H.Kronm.uller,Appl.Phys.Lett.76(2000)1054.[25]C.Chen,M.S.Walmer,M.H.Walmer,S.Liu,G.E.Kuhl,G.K.Simon,MRS Symp.Proceedings of the‘AdvancedHard and Soft Magnets,’Vol.577,1999,p.277.[26]J.F.Liu,Y.Zhang,D.Dimitrov,G.C.Hadjipanayis,J.Appl.Phys.85(1999)2800.[27]A.Yan,W.Y.Zhang,H.W.Zhang,B.Shen,J.Magn.Magn.Mater.210(2000)L10.[28]A.Yan,W.Y.Zhang,H.W.Zhang,B.Shen,Mater.Sci.Eng.B68(1999)111.[29]H.Nakamura,S.Sugimoto,M.Okada,M.Homma,Mater.Chem.Phys.32(1992)280.[30]C.N.Christodoulou,T.Takeshita,J.Alloys Comp.196(1993)155.[31]C.Mishima,N.Hamada,H.Mitarai,Y.Honkua,Proceedings of the16th International Workshop on RE Magnets and their Appl.,Sendai,Japan,2000,p.873. [32]C.Mishima,N.Hamada,H.Mitarai,Y.Honkua,IEEETrans.Magn.37(2001)2467.[33]O.Gutﬂeisch,J.Phys.D33(2000)R157.[34]T.Tomida,N.Sano,K.Hanafusa,H.Tomizawa,S.Hirosawa,Acta Metall.47(1999)875.[35]O.Gutﬂeisch, B.Gebel,N.Mattern,J.Magn.Magn.Mater.210(2000)5.[36]O.Gutﬂeisch,A.Teresiak,B.Gebel,K.-H.M.uller,N.B.Cannesan,D.N.Brown,I.R.Harris,IEEE Trans.Magn.37(2001)2471.[37]R.N.Faria,A.J.Williams,I.R.Harris,J Alloys Comp.287(1999)L10.[38]M.Kubis,O.Gutﬂeisch,K.H.M.uller,I.R.Harris,L.Schultz,J.Appl.Phys.83(1998)6905.[39]O.Gutﬂeisch,M.Kubis,A.Handstein,K.-H.M.uller,L.Schultz,Appl.Phys.Lett.73(1998)3001.[40]O.Gutﬂeisch,A.Bollero,D.Eckert,B.Gebel,M.Kubis,K.-H.M.uller,L.Schultz,Proceedings of the16th International Workshop on RE Magnets and their Appl., Sendai,Japan,2000,p.883.[41]N.Yoshikawa,H.Yamada,Y.Iwasaki,K.Nagata,Y.Kasai,Proceedings of the13th International Workshop on RE Magnets and their Appl.,Birmingham,UK,1994, p.635.[42]W.Gr.unberger,D.Hinz,D.Schl.a fer,L.Schultz,J.Magn.Magn.Mater.157/158(1996)41.[43]A.Kirchner,D.Hinz,V.Panchanathan,O.Gutﬂeisch,K.H.M.uller,L.Schultz,IEEE Trans.Magn.36(2000) 3288.[44]Y.Kaneko,IEEE Trans.Magn.36(2000)3275.[45]W.Rodewald,R.Blank,B.Wall,G.W.Reppel,H.D.Zilg,Proceedings of16th International Workshop on RE Magnets and their Appl.,Sendai,Japan,2000,p.119.O.Gutﬂeisch et al./Journal of Magnetism and Magnetic Materials242–245(2002)1277–12831283。

等离子表面处理英文

等离子表面处理英文Plasma Surface Treatment: An Overview of Principles, Applications, and Advantages.Introduction.Plasma surface treatment is a technology that has revolutionized the way materials are processed and prepared for various applications. It involves the use of ionized gas, known as plasma, to modify the surface properties of materials, enhancing their performance in diverse fieldslike electronics, biomedicine, and more. This articledelves into the principles, applications, and benefits of plasma surface treatment.Principles of Plasma Surface Treatment.Plasma is a state of matter distinct from solid, liquid, and gas. It consists of a mixture of positive ions,negative electrons, and neutral atoms or molecules. Plasmasurface treatment involves exposing the surface of a material to a plasma generated using high-frequency electromagnetic fields or direct current.During this process, the high-energy particles in the plasma interact with the surface atoms of the material, causing them to undergo physical and chemical changes. These changes can range from simple cleaning of the surface to complex chemical reactions that result in the formation of new compounds or modifications in the surface structure.Applications of Plasma Surface Treatment.1. Surface Cleaning and Etching: Plasma treatment is effective in removing organic and inorganic contaminants from material surfaces, preparing them for further processing or coating.2. Surface Activation and Coating Adhesion: Plasma treatment can enhance the wettability of material surfaces, making them more suitable for adhesion of coatings, paints, and adhesives.3. Modification of Surface Properties: Plasma treatment can introduce specific chemical groups or functionalitiesto material surfaces, altering their wettability, conductivity, or biocompatibility.4. Microand Nanostructuring: Plasma processes can be used to create microand nanostructures on material surfaces, enhancing their tribological properties, optical properties, or cell adhesion capabilities.5. Biomedical Applications: Plasma surface treatment is widely used in biomedicine to improve the biocompatibilityof implants, stents, catheters, and other medical devices.Advantages of Plasma Surface Treatment.1. Versatility: Plasma treatment can be applied to a wide range of materials, including metals, plastics, ceramics, and composites.2. Precision and Controllability: Plasma processesoffer precise control over the surface modifications, allowing for targeted changes in specific areas.3. Economic Viability: Plasma surface treatment is often more cost-effective than traditional surface modification methods, as it requires less material waste and energy consumption.4. Compatibility with Other Processes: Plasma-treated surfaces are compatible with subsequent processing steps, such as coating, printing, bonding, and more.5. Enhanced Performance: Plasma treatment can significantly improve the performance of materials in terms of durability, wear resistance, corrosion resistance, and biocompatibility.Conclusion.Plasma surface treatment is a powerful technology that has the potential to revolutionize various industries. Its ability to precisely modify material surfaces withoutaffecting the bulk properties offers unique advantages compared to traditional surface modification methods. As research and development continue in this field, we can expect to see more innovative applications of plasma surface treatment in the future.。

石先明博士简历

石先明博士美国蒙大拿州立大学土木工程系（研究型）教授美国西部交通研究所腐蚀与可持续道桥实验室创始人兼主任联系方式Xianming Shi, PhD, PEWestern Transportation Institute (WTI)PO Box 174250，Montana State UniversityBozeman, MT 59717, USAPhone: 01-406-994-6486 (Office)Email: Xianming.shi at Web: /me/faculty/Shi/ResearcherID: /rid/A-5108-2012个人简历1974年12月生于湖南益阳89-93年北京化工学院腐蚀与防护专业，获理学学士学位93-96年天津大学应用化学专业，获理学硕士学位，师从宋诗哲教授96-99年中国科学院化学研究所高分子化学专业，获哲学博士学位，师从余云照研究员99-00年美国蒙大拿州立大学环境工程专业学习，师从Z. Lewandowski教授00-02年美国蒙大拿州立大学工业与管理工程专业，获理学硕士学位，师从D. W. Boyd教授2002年至今历任美国西部交通研究所研究助理，助理研究员，研究员，资深研究员2004年 1 月创建腐蚀与可持续道桥实验室，担任主任 (Founding Director）至今2005 年 5 月至2010年 6 月任美国西部交通研究所冬季道路养护研究室主任2007年7月被美国蒙大拿州立大学土木工程系破格晋升为（研究型）副教授2007 年获美国注册工程师资格2009 年8月至2012年 6 月任美国蒙大拿州立大学机械与工业工程系兼职副教授2012年7月被美国蒙大拿州立大学土木工程系晋升为（研究型）教授主要研究兴趣∙材料科学（新型能源、多功能材料、高性能涂料、渗入型密封剂、高分子改性温拌沥青、超高掺量粉煤灰混凝土、透水混凝土、自愈合混凝土、环保型融雪剂等）∙服役环境对混凝土/沥青/金属材料耐久性之影响（混凝土腐蚀传感器、桥墩／路面无损探测、道桥养护及修复技术等）∙可再生资源／回收材料在土木工程中之应用（粉煤灰、化学石膏、矿渣、煤矸石及其它工农业副产物之废料资源化）∙纳米科技在可持续道桥、绿色建筑及环境保护中之应用研究成果近年来先后负责科研项目36项，共同负责项目7项。

冶金专业英语(全)

有色冶金专业英语（适用于冶金工程专业）2009年9月Lesson 3 Ore DressingOre dressing 选矿Concentrate v. 富积，浓缩，集聚n. 精矿，浓缩物Concentration n. 集中，浓缩，浓度Acid concentration 酸浓度Bulk n. 正体，主体，团块Gangue n. 脉石，尾矿，矿脉中的夹杂物Tailing n. 尾矿Severance n. 分离，隔离，碎散Beneficiation n. 分选Comminution n. 粉碎Run-of-mine n. 原矿Middling n. 中矿Liberation n. 解离Crush n. v. 粉碎，碾碎，挤压Grind n. v. 研磨，磨细Screen n. v. 筛，筛分Jigging n. 跳选，跳汰选Hand picking 手选Luster n. 光泽，光亮v. 闪光，发光Specific gravity 比重Magnetic permeability 磁导率Inductive charging 感应电荷Electrostatic separation 静电分离Fracture n. 断口，裂缝Automatic sorting of radioactive natures放射性自动选矿Magnitude n. 大小，尺寸，量级，强度，等级Magnetic separation 磁选Magnetic field 磁场Gravity concentration 重力选矿Medium n. 介质，媒介，中间物，培养基Dilate v. （使）膨胀，扩张，扩大Dilated bed 松散床层Dilation n. 膨胀系数，传播，伸缩，蔓延Lip n. 凸出部分，唇部Diverse adj. 不同的，互异的，各种各样的Table n. 摇床，淘汰盘Tabling 摇床选，淘汰选Motion n. 运动，输送，行程，机械装置，运动机构Sink-float separation 重介质分选Suspension n. 悬浮物，悬浮液Cone n. 圆锥体，锥形漏斗，圆锥破碎机Stir n. v. 移动，摇动，搅拌Stirrer n. 搅拌器，搅拌机Rotary adj. 旋转的，回转的，转动的Circumference n. 圆周，周边Rotating motion 旋转装置，旋转设备Floatation n. 浮选Pulp n. 矿浆，浆料v. 制浆，浆化Sluice n. 槽，排水道，水槽Froth floatation 泡沫浮选Hematite n. 赤铁矿Pyrolusite n. 软锰矿Diamond n. 金刚石Graphite n. 石墨Ore dressing concerns with the technology of treatment of ores to concentrate their valuable constituents (minerals) into products (concentrate) of smaller bulk, and simultaneously to collect the worthless material (gangue) into discardable waste (tailing). The fundamental operations of ore-dressing processes are the breaking apart of the associated constituents of the ore by mechanical means (severance) and the separation of the severed components (beneficiation) into concentrate and tailing, using mechanical or physical methods which do not effect substantial chemical changes.1Severance. Comminution is a single, or multistage processes whereby ore is reduced from run-of-mine size to that size needed by the beneficiation processes. The process is intended to detailed control, a class of particles containing both mineral and gangue (middling particles) are also produced. The smaller the percentage of middling the greater the degree of liberation. Comminution is divided into crushing (down to 6-to 14-mush) and grinding (down to micron size). Crushing is usually done in three stages: coarse crushing from run-of-mine size to 4-6 in., or coarser; intermediate crushing down to about 1/2 in.; and fine crushing to 1/4 in. or less. Screen is a method of sizing whereby graded products are produced, the individual particles in each grade being of nearly the same size. In beneficiation, screening is practiced for two reasons: as and integral part of the separate on process, for example, in jigging, and to produce a feed of such size range as is compatible with the applicability of the separation process.Beneficiation. This step consists of two fundamental operations: the determination that an individual particle is either a mineral or a gangue particle (selection); and the movement of selected particles via different paths (separation) into the concentrate and tailing products.2 When middling particles occur, they will either be selected according to their mineral content and then caused to report as concentrate or tailing, or be separated as a third product (middling).3 In the latter case, the middling is reground to achieve further liberation, and the product is fed back into the stream of material being treated.Selections based upon some physical or chemical property in which the mineral and gangue particles differ in kind or degree or both. Thus in picking, the old form of beneficiation, color, luster, and shape are used to decide whether a lump of ore is predominantly mineral or gangue. Use is made of differences in other physical or chemical properties, such as specific gravity, magnetic permeability, inductive charging (electrostatic separation), surface chemical properties, bulk chemical properties, weak planes of fracture (separation by screening), and gamma-ray emission (automatic sorting of radioactive nature).Separation is achieved by subjecting each particle of the mixture to a set of forces that is usually the same irrespective of the nature of the particles excepting for the force based upon the discriminating property. This force may be present for both mineral and gangue particles but differing in magnitude, or it may be present for one type of particle and absent for the other. As a result of this difference separation ispossible, and the particles are collected as concentrate or tailing.Magnetic separation utilizes the force exerted by a magnetic field upon magnetic materials to counteract partially or wholly the effect of gravity. Thus under the action of these two forces different paths are produced for the magnetic and nonmagnetic particles.Gravity concentration is based on a discriminating force, the magnitude of which varies with specific gravity. The other force that is usually operating in gravity methods is the resistance to relative motion exerted upon the particles by the fluid or semi-fluid medium in which separation takes place Jigging is a gravity method that separates mineral from gangue particle by utilizing an effective difference in settling rate through a periodically dilated bed. During the dilation heavier particles work their way to the bottom while the lighter particles remain on top and are discharged over the lip. Jigging is practiced on materials that are liberated upon being reduced to sizes ranging from 3/2 in., down to several millimeters. It has been used on such diverse ores as coal, iron ores, gold and lead ores.Tabling is a gravity method in which the feed, introduced onto an inclined plane and reciprocated deck, moves in the direction of motion while simultaneously being washed by a water film which moves it also at right angles to the motion of the deck.4 The heavier mineral and the lighter gangue are usually collected over the edges of the deck. The boundary between the heavier mineral and lighter gangue particles is roughly a linear diagonal band on the deck of the table. This diagonal band is not stationary; rather it tends to move about a mean position. In practice therefore, a third product, the middling, is collected between the discharge edges of concentrate and gangue. If the feed to the table has been crushed or ground to produce liberation, then the middling is returned to the feed. If liberation has not been achieved, the middling is returned to the crushing-grinding section of the mill. Tables may be used to treat relatively coarse material (sand tables) with sizes ranging from about 2~3 mm down to 0.07 mm.Sink-float separation is the simplest gravity method and is based on existing differences in specific gravity. The feed particles are introduced into a suspension, the specific gravity of which is between that of the mineral and gangue particles, with the result that particles of higher specific gravity sink while those of lower specific gravity float.5The separator is a cone equipped with a slowly operated stirrer which serves to impart slow rotary motion to the suspension and prevent the suspension from settling out on the walls. Feed is introduced at one point of the circumference and is slowly moved by the rotating motion of the suspension. By the time this material has reached the discharge point on the circumference, those particles whose specific gravity is greater than that of the suspension have moved down through the suspension so that only float particles are discharged at the top, the sink particles are discharged at the bottom.Flotation is used to separate valuable minerals from waste rock or gangue, in which the ground ore is suspended in water and, after chemical treatment, subjected to bubbles of air. The minerals that are to be floated attach to the air bubbles, rise through the suspension, and are removed with the froth that forms on top of the pulp. Froth flotation was first used to recover sulfide minerals that were too fine to be recovered by gravity concentrators such as jigs, tables, and sluices. Froth flotation is also used to concentrate oxide minerals such as hematite (Fe2O3) and pyrolusite (MnO2), and native elements such as sulfur, silver, gold, copper and carbon (both graphite and diamond). Froth flotation is also used to separate the silicate minerals.Lesson 5 Materials Science and EngineeringEmbrace 包括Ceramics 陶瓷Inanimate 无生命的Homogeneous 均匀的Predominate 主导Rigidity 刚性Weldability 可焊性Composite 复合材料Spectrum 种类Brass 黄铜Bronze 青铜Invar 因钢(NiFe) Cement 水泥Ferrite 铁素体Garnet 石榴石PVC 聚氯乙烯Polyethylene 聚乙烯PTFE 聚四氟乙烯Terylene 涤纶nylon 尼龙leather 皮革reinforced 增强dispersion 弥散supersonic 超声波optimum 最优fabrication 人工制作invariable 不变的corrosion 腐蚀fatigue 疲劳assess 评估1. Materials Science“Materials Science” is a subject for engineers of the modern age. It embraces a study of different materials regarding their structures, properties and uses. The “material” here does not refer to all matter in the Universe. If this were so, it would include all the physical sciences and the life sciences form astronomy to zoology. We can restrict the definition only to matter useful to mankind. Even here, the range is too broad for the purposes of the engineer. For example, we can list a large number of things useful, to man, such as food, medicines, explosives, chemicals, water, steel, plastics and concrete, only a few of which qualify as engineering materials. We have then to be more specific, and define materials as that part of inanimate matter that is useful to the engineer in the practice of his profession.1Recently the term, materials refer only to solid materials, even though it is possible to quote a number of examples of liquid and gaseous materials such as sulfuric acid and steam, which are useful to the engineer.The word ‘science’ refers to the physical science, in particular to chemistry and physics. As we confine ourselves mainly to solid in material science, the subject is related to solid state chemistry and solid state physics. The engineering usefulness of the matter under study is always deep in mind. In this respect,material ceramics science comes heavily from the engineering sciences such as metallurgy, and polymer science. These, in their own time, have grown out of their interaction with the basic sciences of chemistry and physics.Therefore, Material Science refers to that branch of applied science concerned with investigating the relationship existing between the structure of materials and their properties, and it concerns with the interdisciplinary study of materials for entirely practical purposes.2 Material science has developed rapidly during the last ten years. The new approach of material science has paid of handsomely in many ways and they have solved the problems in selection of right materials in complex situations.2. Classes of Engineering MaterialsWithin the scope of material science, the engineering materials may be classified in three broad groups according to their mode of occurrence:(1) Metals and alloys(2) Ceramics(3) Organic polymers.A metal is an elemental substance. An alloy is a homogeneous mixture of two or more metals or a metal and nonmetal. Among the solid materials, metals and alloys predominate because of their useful characteristics of hardness, strength, rigidity, formability, machinability, weldability, conductivity and dimensional stability.Ceramics are materials consisting of phases. A phase is a physically separable and chemically homogeneous constituent of a material. These are themselves compounds of metallic and non-metallic elements. All metallic compounds, rocks minerals, glass, glass-fiber, abrasives and all fired clays are ceramics.Organic materials are those materials derived directly from carbon. They usually consist of carbon chemically combined with hydrogen, oxygen or other nonmetallic substances, and their structures are, in many instances, fairly complex. Plastics and synthetic rubbers are common organic engineering materials.Table 1 shows a broad spectrum of engineering materials which shows not only typical examples from each of these three groups but also gives a number of examples of materials which are composite up of two groups.3 In general, in each and every engineering application we find material from all the three basic types of materials described above.Table 1. Some important grouping of materialsSince the engineer must specify the materials for TV sets, computers, suspension bridges, oil refineries, rocket motors, nuclear reactors, or supersonic transports he must have sufficient knowledge to select the optimum material for each application. Although experience provides the engineer with a starting point for selection of materials, the skill of the engineer will be limited unless he understands the factors that contribute to the properties of materials.43. Selection of MaterialsRight type of material is to be selected for a particular type of work. The selections of the right materials for given requirements, the proper use of those materials, development of new ways of using them for greater effectiveness, all are direct responsibility of the engineer.To fulfill this responsibility, the engineer must have a thorough knowledge of the nature and behavior of materials. The study of the nature of materials has its foundation in chemistry and physics and that of behavior of materials involves the application, of the principles of the nature of materials, under the varied conditions found in engineering practice.3 This behavior of materials is determined by composition, structure, service conditions, and the interactions among them. All materials have limitations within whichthey perform well but beyond which they cannot be used satisfactorily.However, the selection of a material for a specific application is invariably a thorough, lengthy, and expensive investigation. Almost always more than one material is suited to the application, and the final selection is a compromise that weights the relative advantages and disadvantages. The varied requirements to three broad demands: (1) Service requirements; (2) Fabrication requirements; (3) Economic requirements.The service requirements have important role in material selection. The material must stand up to service demands. Such demands commonly include dimensional stability, corrosion resistance, adequate strength, hardness, and toughness, heat resistance. In addition to any such basic requirements, other properties may be required such as a low electrical resistance, high or low heat conductivity, fatigue resistance, or others.Fabrication requirements are also to be considered in material selection. It must be possible to shape the material, and to join it to other material. The assessment of fabrication requirements concerns questions of machinability, hardenability, heat treatability, ductility, castability, and weldability, qualities that are sometime quite difficult to assess.Along with the above two requirements, the economic requirements give final shape in material selection. Goods must be produced at lower cost. The object is the minimum over all cost of the component to be made, and this objective is sometimes attained only by increasing one or more of the cost componentsLesson 6 MetallurgyMetallurgy n. 冶金，冶金学Non-ferrous metallurgy 有色冶金学Chlorine metallurgy 氯化冶金学Powder metallurgy 粉末冶金学Extractive metallurgy 提取冶金学Meteoric iron 陨铁Craftsmanship n. 手艺，技能Craftsman n. 技工，工匠Ornamental adj. 装饰用的，观赏的n. 装饰品Metalworking n. 金属加工Ceremonial adj. 正式的，礼仪的，仪式的Decorative adj. 装饰的Decorative arts 装饰艺术Cast n. v. 铸造，铸件Process metallurgy 过程冶金Production metallurgy 生产冶金Physical metallurgy 物理冶金Chemical metallurgy 化学冶金Mechanical metallurgy 机械冶金，力学冶金Unit operation 单元操作Unit process 单元过程Flux n. 熔剂Solvent n. 溶剂Slag n. 渣，炉渣v. 造渣Electrolyte n. 电解质，电解液Depletion n. 用尽，消耗，贫化，提取金属Deposit n. v. 沉积，沉淀，电积Blast furnace 鼓风炉，高炉Crude iron 生铁crystal structure 晶体结构neutron n. 中子diffraction n. 衍射crystal imperfection 晶体缺陷plastic deformation 塑性变形metallography n. 金相学microscopy n. 显微镜学，显微技术forging n. 锻造，锻件blowhole n. 气孔thermodynamics n. 热力学kinetics n. 动力学Steelmaking n. 炼钢Scrape n. 废料Leach v. 浸出，溶出Electrochemical reduction cell 电化学还原电池Inorganic chemistry 无机化学Pyro-metallurgy 火法冶金Hydro-metallurgy 湿法冶金elevated temperature 高温reduce v. 还原reduction n. 还原charcoal n. 木炭，炭spontaneous adj. 天然的，自动的，自发的residue n. 残渣，剩余物，残余物，炉渣roasting n. 焙烧pig iron 粗铁，生铁refine v. n. 精炼，提纯，纯化uranium n. 铀tungsten n. 钨molybdenum n. 钼isolate v. 隔离，隔绝，切断recovery n. 回收，回收率，回复，恢复scope n. 范围，领域，目标revert n. 返料metalloid n. 类金属adj. 类金属的selenium n. 硒tellurium n. 碲amenability n. 可控制性，可处理性adaptability n. 适应性hafnium n. 铪zirconium n. 锆flexibility n. 适应性，灵活性Metallurgy is the science of metallic materials. Metallurgy as a branch of engineering is concerned with the production of metals and alloys, their adaptation to use, and their performance in service. As a science, metallurgy is concerned with the chemical reactions involved in the processes by which metals are produced and the chemical, physical, and mechanical behavior of metallic materials.1Metallurgy has played an important role in the history of civilization. Metals were first produced more than 6000 year age. Because only a few metals, principally gold, silver, copper and meteoric iron, occur in the uncombined state in nature, and then only in small quantities, primitive metallurgists had to discover ways of extracting metals from their ores. Fairly large-scale production of some metals was carried out with technical competence in early Near Eastern and Mediterranean civilizations and in the Middle Ages in central and northern Europe. Basic metallurgical skills were also developed in other parts of the world.The winning of metals would have been of little value without the ability to work them. Great craftsmanship in metalworking developed in early times; the objects produced included jewelry, large ornamental and ceremonial objects, tools and weapons. It may be noted that almost all early materials and techniques that later had important useful applications were discovered and first used in the decorative arts.2 In the Middle Ages metalworking was in the hands of individual or groups of craftsmen. The scale and capabilities of metalworking developed with the growth of industrial organizations. Today’s metallurgical plants supply metals and alloys to the manufacturing and construction industries in many forms such as beams, plates, sheets, bars, wire, and castings. Rapidly developing technologies such as communications, nuclear power, and space exploration continue to demand new techniques of metal production and processing.The field of metallurgy may be divided into process metallurgy, (production metallurgy, extractive metallurgy) and physical metallurgy. According to another system of classification, metallurgy comprises chemical metallurgy, mechanical metallurgy (metal processing and mechanical behavior in service), and physical metallurgy. The more common division into process metallurgy and physical metallurgy, which isadopted here, classifies metal processing as a part of process metallurgy and the mechanical behavior of metals as a part of physical metallurgy.Process metallurgy Process metallurgy, the science and technology used in the productions of metals, employs some of the unit operations and unit processes as chemical engineering. These operations and processes are carried out with ores, concentrates, scrap metals, fuels, fluxes, slag, solvents, and electrolytes. Different metal adopts different combinations of operations and processes, but typically the production of a metal involves two major steps. The first is the production of an impure metal from ore minerals, commonly oxides or sulfides, and the second is the refining of the reduced impure metal, for example, by selective oxidation of impurities or by electrolysis. Process metallurgy is continually challenged by the demand for metals that have not been produced previously or are difficult to produce; by the depletion of the richer and more easily processed ores of the traditional metals; and by the need for metals of greater purity and higher quality. The mining of leaner ores has greatly enhanced the importance of ore dressing methods for enriching raw materials for metal production. Several nonferrous metals are commonly produced from concentrates. Iron ores are also increasingly treated by ore dressing.Process metallurgy today mainly involves large scale operations. A single blast furnace produces crude iron at the rate of 3,00~11,000 tons per day. A basic oxygen furnace for steelmaking consumes 800 tons of pure oxygen together with required amounts of crude iron and scrap to produce 12,000 tons of steel per day. Advanced methods of process analysis and control are now being applied to such processing system. The application of vacuum to extraction and refining processes, the leaching of low-grade ores for the extraction of metals, the use of electrochemical reduction cells, and the refining of reactive metals by processing through the vapor state are other important developments.Because the production of metals employs many different chemical reactions, process metallurgy has been closely associated with inorganic chemistry. Techniques for analyzing ores and metallurgical products originated several centuries ago and represented an early stage of analytical chemistry. Application of physical chemistry to equilibrium and kinetics of metallurgical reactions has led to great progress in metallurgical chemistry.According to temperature at which the process is carried out process metallurgy may be divided into pyrometallurgy and hydrometallurgy. Pyrometallurgy is processes employing chemical reactions at elevated temperatures for the extractions of metals from ores and concentrates. The use of heat to cause reduction of copper ores by charcoal dates from before 3,000 B.C. The techniques of pyrometallurgy have been gradually perfected as knowledge of chemistry has grown and as sources of controlled heating andmaterials of construction for use at high temperature have become available.3Pyrometallurgy is the principal means of metal production.The advantages of high temperature for metallurgical processing are several: chemical reaction rates are rapid, reaction equilibriums change so that processes impossible at low temperature become spontaneous at higher temperature, and production of the metal as liquid or gas facilitates physical separation of metal from residue.4The processes of pyrometallurgy may be divided into preparation processes which convert the raw material to a form suitable for further processing (for example, roasting to convert sulfides to oxides), reduction processes which reduce metallic compounds to metal (the blast furnace which reduces iron oxide to pig iron), and refining processes which remove impurities from crude metal (fractional distillation to remove iron, lead, and cadmium from crude zinc).The complete production scheme, from ore to refined metal, may employ pyrometallurgical processes (steel, lead, tin, zinc), or only the primary extraction processes may be pyrometallurgical, with other methods used for refining (copper, nickel). 5 In some case (uranium, tungsten, molybdenum), isolated pyrometallurgical processes are used in a treatment scheme that is predominately nonpyrometallurgical.Hydrometallurgy is the extraction and recovery of metals from their ores by processes in which aqueous solutions play predominant role. Two distinct processes are involved in hydrometallurgy; putting the metal values in the ore into solution via the operation known as leaching; and recovering the metal values from solution, usually after a suitable solution purification or concentration step, or both. The scope of hydrometallurgy is quite broad and extends beyond the processing of ores to the treatment of metal concentrates, metal scrap and revert materials, and intermediate products in metallurgical processes. Hydrometallurgy enters into the production of practically all nonferrous metals and or metalloids, such as selenium and tellurium.The advantages of hydrometallurgy are applicability to low-grade ores (copper, uranium, gold, silver), amenability to the treatment of materials of quite different compositions and concentrations, adaptability to separation of highly similar materials (hafnium from zirconium), flexibility in terms of the scale of operations, simplified materials handling as compared with pyrometallurgy, and good operational and environmental control.Physical metallurgy investigates the effects of composition and treatment on the structure of metal and the relations of the structure to the properties of metals. Physical metallurgy is also concerned with the engineering applications of scientific principles to the fabrication, mechanical treatment, heat treatment, and service behavior of metals.The structure of metals consists of their crystal structure, which is investigated by x-ray, electron, and neutron diffraction, their microstructure, which is the subject or metallography, and their macrostructure. Crystal imperfections provide mechanisms for processes occurring in solid metals, for example, the movement of dislocations results in plastic deformation. Crystal imperfections are investigated by x-ray diffraction and metallographic methods, especially electron microscopy. The microstructure is determined by the constituent phases and the geometrical arrangement of the microcrystals (grains) formed by those phases. Macrostructure is important in industrial metals. Phase transformations occurring in the solid state underlie many heat-treatment operations. The thermodynamics and kinetics of these transformations are a major concern of physical metallurgy. Physical metallurgy also investigates changes in the structure and properties resulting from mechanical working of metals.Lesson 12 Calcination and RoastingCalcination n. 焙烧，煅烧 calcine 焙砂 Decomposition n. 分解，裂解 Metal hydrate 金属氢氧化物 Carbonate n. 碳酸盐 Basic sulphate 碱式硫酸盐 Rotary kiln 回转窑 Shaft furnace 竖炉 Dead roasting 死烧 Sulphating roasting 硫酸化焙烧 Reduction roasting 还原焙烧 equillibrium constant 平衡常数 kellog diagram 凯洛格相图 predominance n. 优势，优越 predominance area 优势区 partial roasting 部分焙烧 selective roasting 选择性焙烧 chloridizing roast 氯化焙烧 smelt n. v. 熔炼noble adj. 贵重的，惰性的noble metal 惰性金属，贵金属 hypothetical adj. 假定的，有前提的 fume n. 烟气halide n. 卤化物volatilizing roast 挥发焙烧 magnetizing roast 磁化焙烧magnetite n. 磁铁矿flash roaster 闪速焙烧炉,飘悬焙烧炉 inject v. 喷射，喷入fluidise v. 流态化fluidized bed roaster 流态化焙烧炉 burner n. 喷嘴suspend v. 悬浮，漂浮fluo-solids roaster 流化-闪速焙烧炉 matte n. 冰铜，锍reverberatory furnace 反射炉1. CalcinationCalcination involves the chemical decomposition of the mineral and is achieved by heating to above the mineral’s decom position temperature (T D ) or by reducing the partial pressure of the gaseous product (P H 2O , P CO 2) below that of its equilibrium partial pressure for a certain constant temperature.1 For example,CaCO 3 = CaO + CO 2T D = 900℃ (under standard thermodynamic conditions)Calcination is mainly used to remove water, CO 2 and other gases which are chemically bound in metal hydrate and carbonates as these minerals have relatively low decomposition temperatures.2Calcinations are conducted in rotary kilns, shaft furnaces or fluidized bed furnaces.2. Roasting of metal concentratesThe most important roasting reactions are those concerning metal sulfide concentrates and involve chemical combination with the roasting atmosphere.Possible reactions include:MS + 3O 2 = 2MO + 2SO 2 (dead roast)MS + 2O 2 = MSO 4 (sulfating roast)MS + O 2 = M + SO 2 (reduction roast)Other equilibria which need to be taken into account include:(1/2)S 2 + O 2 = SO 2 andSO 2 + (1/2)O 2 = SO 3。

光电化学电池(PEC)催化全裂解水制氢技术研究进展东莞理工

光电化学电池（PEC）催化全裂解水制氢技术研究进展摘要：主要介绍太阳能光电学电池（PEC）分解水制氢技术的基本原理以及发展历史和研究现状, 和光阳级、光阴极的选材要求及发展，并在此基础上分析影响该技术发展的一些因素催化电极的制备以及太阳能光化学电池的结构等一系列问题。

Abstract: This paper mainly introduces the solar energy photoelectricity cell (PEC) split water the basic principle of hydrogen production technology and the development history and research status, and light Yang, material requirements and development of the photocathode, based on the analysis of the factors affecting the development of the technology of catalytic electrode preparation, and the structure of solar photochemical batteries a series of problems.关键词:PEC 制氢制备电池的结构前言在新能源领域中,氢能已普遍被认为是一种最理想的绿色能源,这是它的独特的优点所决定的.在所有元素中, 氢重量最轻,它能够以气、液、固 3 种形式存在, 能适应贮运及各种应用环境的不同要求 ; 所有气体中, 氢是自然界存在最普遍的元素; 除核燃料外,氢的发热值是所有化石燃料、化工燃料和生物燃料中最高的 ; 氮燃烧性能好 ; 氢气本身无毒,与其他燃料相比氢燃烧时最清洁,水是其唯一产物, 不会对环境产生污染,也不会带来温室效应 ; 氢能利用形式多, 既可作为家用燃料, 又可用于航夭等.制氢的方法有许多种, 但如果能利用可再生能源来制氢, 那将是取之不尽、用之不竭的能源休系.太阳能在所有可再生能源中当为首选.太阳能可以通过分解水或其它许多途径转换成氢能, 即太阳能制氢.这包括许多方法,如太阳能光电化学电池分解水制氢、光化学催化制氢、太阳能生物制氢等, 其中太阳能光电化学(photo-electrochemical,PEC ) 电池分解水制氢技术是很具前景的技术.这是因为PEC 技术是基于太阳能和水, 而这两种物质都是可再生的 ,没有副产品, 不会给环境带来污染;技术相对比较简单;既可小规模应用, 又可大规模开发等等优点.因此,大力发展制氢技术, 特别PEC技术将是未来发展的方向。

不同晶粒尺寸材料的霍尔佩奇关系

不同晶粒尺寸材料中的H-P关系细化晶粒一直是改善多晶体材料强度的一种有效手段。

根据位错理论,晶界是位错运动的障碍,在外力作用下,为了在相邻晶粒产生切变变形,晶界处必须产生足够大的应力集中,细化晶粒可以产生更多的晶界,如果晶界结构未发生变化,则需施加更大的外力才能产生位错塞积, 从而使材料强化。

Hall-Petch 关系就是在位错塞积模型基础上导出的。

H-P关系的历史20世纪50年代初，人们开始研究晶粒尺寸与材料强度的关系，1951年当时还在谢菲尔德大学读书的E. O. Hall在64册装订的《物理学进程表》上发表了三篇文章。

在第三篇文章中，他指出了滑动带的长度或裂纹尺寸与晶粒尺寸成正比，即，式子中的第一项代表了材料的强度，k是常数。

由于技术条件的限制，Hall只能推出成正比的关系，但是x的取值没有具体给出。

当时Hall选取的研究对象是锌但是他发现这个关系应用于低碳钢同样成立。

英国利兹大学的N. J. Petch根据自己在1946-1949年的实验研究和Hall的理论基础发表了一篇论文，这篇论文着重讲述了有关脆性断裂方面的知识，通过测量在低温条件下不同晶粒尺寸的解理强度，Petch把Hall提出的数学关系进行了精确地完善，这个重要的数学关系就以他们的名字命名为霍尔佩奇关系。

即σy代表了材料的屈服极限，是材料发生0.2%变形时的屈服应力σ0.2通常可以用显微硬度Hv来表示σ0表示移动单个位错时产生的晶格摩擦阻力Ky一个常数与材料的种类性质以及晶粒尺寸有关d 平均晶粒直径Hall-Petch关系图由于Hall和Petch所处的年代技术的落后他们能研究的晶粒尺寸还是很大的，所以早期的H-P关系是不完善的，只有图中前半部分。

后半部分是随着科技的进步，逐渐完善的。

近几十年来, 材料的细晶强化研究大量开展。

在一般晶粒尺寸范围内, 材料的强度随晶粒尺寸的变化是符合Hall-Petch 关系的, 但在纳米晶体材料中出现了偏离甚至反Hall-Petch 关系的现象, 因此Hall-Petch 关系的使用具有一定的局限性。

纳米晶的工艺流程

纳米晶的工艺流程Nanocrystals are a fascinating area of study in the field of materials science. These tiny crystals, typically ranging in size from 1 to 100 nanometers, exhibit unique properties that are not found in bulk materials. Nanocrystals have the potential to revolutionize various industries, from electronics to healthcare, due to their size-dependent properties.纳米晶是材料科学领域一个迷人的研究领域。

这些微小晶体的尺寸通常在1到100纳米之间，表现出大面积材料中所没有的独特性质。

由于其尺寸依赖性的特性，纳米晶有潜力彻底改变各个行业，从电子到医疗保健。

The process of fabricating nanocrystals involves several key steps that are crucial for achieving the desired properties. One of the most common methods is the chemical synthesis approach, where precursor materials are mixed in a solution and then subjected to controlled conditions to form nanocrystals. This method allows for precise control over the size, shape, and composition of the nanocrystals, leading to tailored properties for specific applications.制备纳米晶的过程涉及几个关键步骤，对于实现所期望的性质至关重要。

17a-Guo_et_al-2017-Angewandte_Chemie_International_Edition

German Edition:DOI:10.1002/ange.201705426Single-Molecule Magnets Very Important PaperInternational Edition:DOI:10.1002/anie.201705426ADysprosium Metallocene Single-Molecule Magnet Functioning atthe Axial Limit Fu-Sheng Guo,Benjamin M.Day,Yan-Cong Chen,Ming-Liang Tong,Akseli Mansikkam äki,and Richard yfield*Abstract:Abstraction of a chloride ligand from the dyspro-sium metallocene [(Cp ttt )2DyCl](1Dy Cp ttt =1,2,4-tri(tert-butyl)cyclopentadienide)by the triethylsilylium cation produ-ces the first base-free rare-earth metallocenium cation[(Cp ttt )2Dy]+(2Dy )as a salt of the non-coordinating [B-(C 6F 5)4]Àanion.Magnetic measurements reveal that [2Dy ][B-(C 6F 5)4]is an SMM with a record anisotropy barrier up to 1277cm À1(1837K)in zero field and a record magneticblocking temperature of 60K,including hysteresis withcoercivity.The exceptional magnetic axiality of 2Dy is furtherhighlighted by computational studies,which reveal this systemto be the first lanthanide SMM in which all low-lying Kramers doublets correspond to a well-defined M J value,with no significant mixing even in the higher doublets.T he drive to combine the macroscopic properties of bulkmagnetic materials with the quantum effects observed in molecule-based materials has led to an explosion of interest in single-molecule magnets (SMMs).[1]In addition to the con-siderable fundamental interest in SMMs,several systems havebeen proposed for applications in nanoscale devices,such asmolecular spin valves and spin transistors.[2]Molecule-based magnets offer the advantage of well-defined,tunable proper-ties based on correlations that consider how the electronic structure of individual metal ions can be influenced by the coordination environment.For SMMs,the critical factors arenow recognized as being the magnetic anisotropy of individ-ual metal ions and the strength and the symmetry of the ligand field.Many of the most spectacular advances havetherefore been achieved with lanthanide SMMs,especiallycomplexes of the highly anisotropic Ln 3+cations of terbium,dysprosium,holmium,and erbium.[3–6]One of the most striking trends to have emerged recently is that improved properties can be achieved by targeting the synthesis of structurally simple monometallic SMMs rather than complex polynuclear compounds.This approach seem-ingly provides the most facile means of controlling thesymmetry of the lanthanide coordination site,allowing progress towards SMM properties being observed at practicaltemperatures.A transformative breakthrough came with the report of slow magnetic relaxation in a D 4d -symmetricmonometallic terbium phthalocyanine SMM,[7]with many derivatives of these systems showing enhanced properties such as larger effective energy barriers to reversal of the magnetization (the anisotropy barrier,U eff )as a result of simple modifications to the ligand periphery.[8]A recent series of reports on D 5h -symmetric SMMs with the general formula [Dy(OR)2(L)5]+have produced huge U eff values,[9]however,even in these remarkable SMMs,the magnetic hysteresisproperties typically feature zero-field quantum tunneling of the magnetization (QTM),which precludes potential appli-cations in information storage.Our contributions have focused on cyclopentadienyl (Cp)ligated dysprosium SMMs of the type [(Cp)2Dy(E)]n (n =2,3)with various Cp ligands and a wide variety of heteroatom donor ligands,including systems with E =N,P ,As,Sb,S,and Se donors.[10]The key magneto–structural correlation arising from this work is that the [Cp]Àligands provide a dominant axial crystal field that enhances the magnetic anisotropy of Dy 3+,whereas the heteroatom donor ligands moderate the anisotropy,thus limiting U eff and enabling zero-field QTM.[11]The logical conclusion from our studies is therefore that removing the equatorial ligands to give a discrete metal-locenium cation of the type [(Cp)2Dy]+should dramatically increase the anisotropy barrier and the blocking temperature,T B .Our strategy for targeting a base-free [(Cp)2Dy]+cation as a salt of non-coordinating anions first sought to synthesize a compound of the type [(Cp)2MX],and then to abstract a halide ligand,X.To stabilize the putative cation,a bulky cyclopentadienide ligand was deemed necessary,therefore we opted for 1,2,4-tri(tert -butyl)cyclopentadienide (Cp ttt ).Halide abstraction from a hard lanthanide cation should require a highly electrophilic reagent,and the readily accessible triethylsilylium-containing salt [(Et 3Si)2(m -H)][B(C 6F 5)4]was deemed to be an excellent candidate.[12]We reasoned that the driving force for halide abstraction would be greater with X =chloride,hence our initial target compound was [(Cp ttt )2DyCl](1Dy ;Scheme 1).Compound 1Dy was synthesized by refluxing [DyCl 3(THF)3.5]with two equivalents of KCp ttt in toluene for[*]Dr.F.-S.Guo,Dr.B.M.Day,yfield School of ChemistryThe University of ManchesterOxford Road,Manchester,M139PL (UK)E-mail:yfield@Y .-C.Chen,Prof.Dr.M.-L.TongKey Laboratory of Bioinorganic and Synthetic Chemistry of the Ministry of Education,School of Chemistry,Sun-Yat Sen University Guangzhou 510275(P.R.China)A.Mansikkam äkiDepartment of Chemistry,Nanoscience Center,University of Jyv äs-kyl äP.O.Box 35,Jyv äskyl ä,40014(Finland)Supporting information and the ORCID identification number(s)for the author(s)of this article can be found under:https:///10.1002/anie.201705426.11445Angew.Chem.Int.Ed.2017,56,11445–114492017Wiley-VCH Verlag GmbH &Co.KGaA,Weinheim茂金属轴向极限氯化物配体1,2,4叔丁基环戊二烯三乙基阳离子稀土非协调阴离子各向异性屏障滞后的矫顽力特殊的磁轴向计算镧系双峰宏观性能大块量子效应纳米器件分子自旋阀自旋晶体管可协调的各向异性配体场镧系元素阳离子合成多核的化合物对称性配位点变革性的突破酞氰单金属衍生物磁化强度公式零场量子隧道储存72h.Subsequent work-up allowed 1Dy to be isolated as single crystals.Crystallographic studies revealed that 1Dy adopts a bent metallocene structure with two symmetry-related Cp ttt ligands (Figure 1,Table S1in the Supporting Information).The Dy ÀCl distance is 2.5400(13) ,the Dy ÀC distances are in the range 2.641(3)–2.781(3) ,the Dy–Cp c distance is 2.413(2) (Cp c =ligand centroid),and the Cp c -Dy-Cp c angle is 147.59-(7)8.Chloride abstraction was achieved by adding a solution of 1Dy in hexane to a suspension of [(Et 3Si)2(m -H)][B(C 6F 5)4]at room temperature.The initially pale solution deposited a yellow precipitate,and the reaction was stirred for three days.The hexane was decanted away and the remaing solid washed with hexane.After addition of dichloromethane,a bright yellow solution was obtained,from which [(Cp ttt )2Dy][B(C 6F 5)4]([2Dy ][B(C 6F 5)4])was crystallized.The discrete cation [(Cp ttt )2Dy]+(2Dy )also adopts a bent metal-locene structure with the Dy ÀC bonds in the range 2.568(6)–2.711(7) ,hence they are significantly shorter (by 0.06 )than those in 1Dy (Figure 1,Table S1).The Dy–Cp c distances of 2.324(1)and 2.309(1) are also commensurately shorter owing to the greater electrostatic attraction of the Cp ttt ligands to the low-coordinate dysprosium center.The Cp c -Dy-Cp c angle in 2Dy is 152.845(2)8,hence overall the cation 2Dy is more compact and slightly closer to linearity than the metallocene unit in 1Dy .Significantly,the shortest Dy···F distance in [2Dy ][B(C 6F 5)4]is 5.8145(4) ,which is far too long to represent even a weak bond,hence the counteranion is truly non-coordinating.Metallocenium cations of formally tripositive metal ions are very rare for non-transition metals.Important examples include the aluminocenium cations,such as [Cp 2Al]+[MeB-(C 6F 5)3]À,which is an initiator for the cationic polymerization of isobutene.[13]The cation 2Dy is the first rare-earth and the first f-block metallocenium cation.The only other base-free rare-earth bis(cyclopentadienyl)complexes are those of the limited selection of stable divalent lanthanides,such as the archetypal compound decamethylsamarocene.[14]Although related to 2Dy ,the rare-earth contact ion-pairs [(Cp*)2M (m -Ph)2BPh 2]show well-defined cation-p bonding interactions between the tetraphenylborate anion and the metal.[15]The temperature dependence of c M T ,where c M is the molar magnetic susceptibility,was measured for 1Dy and [2Dy ][B(C 6F 5)4]in an applied field of 1000Oe.The results are typical of monometallic Dy 3+complexes,and show similar steady decreases down to about 50K (Figures S2,S3).At lower temperatures,a marked difference in the decrease in c M T was observed:for 1Dy ,the decrease continues gradually,whereas for [2Dy ][B(C 6F 5)4]a precipitous drop occurs,which is indicative of strong magnetic blocking.Investigating the AC magnetic susceptibility of 1Dy revealed that the QTM in this system is very severe (Figure S4).The frequency (n )depend-ence of the out-of-phase magnetic susceptibility (c ’’)for 1Dy showed no maxima at any temperature accessible by our SQUID magnetometer,hence it was not possible to extract an anisotropy barrier for this compound.The field-dependence of the magnetization for 1Dy showed a typical S-shaped curve with only very small openings at fields of H %0.1–1.0T (Figure S5).In stark contrast,the AC susceptibility studies on [2Dy ]-[B(C 6F 5)4]using an oscillating field of 5Oe show peaks in c ’’(n )at temperatures of 72–110K in zero applied field,with the position of the peaks showing a strong dependence on temperature and on the AC frequency (Figure 2,Figure S6).From this data,Cole–Cole plots of c ’’versus c ’were obtained and fitted using a generalized Debye model (Figure S7),which produced a -parameters in the range 0–0.036,indicating an extremely narrow distribution of relaxation times.Further analysis of this data by plotting the relaxation time,t ,as a function of reciprocal temperature produced a linear relationship,revealing that the magnetic relaxation in [2Dy ]-[B(C 6F 5)4]proceeds solely via a thermal mechanism (Figure 2).Fitting the data to the Arrhenius lawt À1¼t À10eÀU eff =k B Tyielded a new record barrier of U eff =1277(14)cm À1(t 0=8.12 10À12s),slightly surpassing the previous record set by [Dy(O t Bu)2(py)5]+.[9a]To probe the magnetic relaxation behavior at lower temperatures,DC magnetic measurements were employed to extract relaxation times from plots of the remnant magnet-ization as a function of time (Figure S8).The result of this analysis is that the linear dependence of t on T persists down to 53K,which,strikingly,corresponds to a relaxation time of t =100s,and can therefore be used to define the magnetic blocking temperature,T B ,for 2Dy as 53K.[3]The most notable recent example of an SMM for which comparable data were reported is a the radical-bridged species [Tb 2(N 2){N-(SiMe 3)2}4(thf)2]À,[3]which has a 100s blocking temperature of only 13.9K,hence the blocking temperature for [2Dy][B-Scheme 1.Synthesis of [2Dy ][B(C 6F 5)4]from 1Dy.Figure 1.Molecular structure of 1Dy (left)and 2Dy (right).Thermal ellipsoids set at 50%probability and hydrogen atoms omitted for clarity.2017Wiley-VCH Verlag GmbH &Co.KGaA,WeinheimAngew.Chem.Int.Ed.2017,56,11445–11449(C 6F 5)4]is by far the largest ever reported,and provides a major advance towards the development of SMMs that function above the symbolic temperature 77K,at which nitrogen liquefies.In the extended low temperature range,the relaxation develops a slight curvature,suggesting that Raman relaxation is more dominant.The equation t À1¼t À10e ÀU eff =k B T þCT n ,in which C and n are the Raman parameters,was used to fit the full range data.This analysis produced U eff =1256(14)cm À1,t 0=1.09 10À11s,C =1.81 10À9s À1K Àn and n =3.92(0.38).Another definition of blocking temperature is the temper-ature at which the field-cooled (FC)and zero-field-cooled(ZFC)magnetic susceptibility diverge.[9a]For [2Dy ][B(C 6F 5)4],this divergence occurs at 60K,which further illustrates the magnetization blocking and is broadly consistent with the temperature when the relaxation time is 100s (Figure S9).The true magnet-like credentials of [2Dy ][B(C 6F 5)4]were established by measuring the field-dependence of the mag-netization using an average field sweep rate of 3.9mTs À1(39Oe s À1).Under these conditions,the results are remark-able,with the M (H )loops remaining open up to 60K,which is substantially higher than any previously observed hysteresis in an SMM (Figure 2,Figure S10).Even more remarkable is the coercive field of H c =0.06T at 60K.Between temper-atures of 55and 2K,the hysteresis loops are wider still,with the coercive fields in the range 0.19–2.46T.Although comparisons of hysteresis measured for SMMs are rendered complicated by the use of different sweep rates,it is clear that the hysteresis properties of [2Dy ][B(C 6F 5)4]surpass those of the radical-bridged di-terbium species [3]and of the D 5h -symmetric dysprosium complexes,[9]and therefore that our system is the new benchmark for the field.Detailed insight into the magnetic properties of 1Dy and 2Dy was obtained through ab initio calculations,which used the experimentally determined atomic coordinates for all heavy atoms,with the positions of hydrogen atoms being optimized at the DFT level.The energies of the eight lowest Kramers doublets (KDs)of 1Dy and 2Dy of the 6H 15/2multiplet of Dy 3+,along with the principal components of the respective g -tensors and the angles between the ground and excited doublets are listed in Table S2.The principal axes of the ground doublets in 1Dy and 2Dy are oriented towards the centers of the [Cp ttt ]Àligands (Figure 3,Figure S11),in broad agreement with a theoretical study on the hypothetical species [(Cp*)2Dy]+.[16]Focusing on 2Dy ,all except the eighth KD have almost axial g -tensors.Up to the fourth KD,the tensors are essentially perfectly axial,and the axiality remains high in the fifth KD.Above this,the transverse components of the g -tensor become significant,and in the eighth KD the g x component dominates.All excited KDs are roughly parallel with the ground doublet,with the largest deviation of 5.68being that between the ground and the fifth KDs.In contrast,the ground doublet in 1Dy has a fairly axial g -tensor with small but non-negligible transversecomponents,Figure 2.Upper:c ’’(n )in zero applied field for 2Dy and various temper-atures in the range 60–123K using 3K intervals.Middle:Temperature dependence of the relaxation time for 2Dy ,where solid lines are fits using the parameters in the text:red points are from the ACsusceptibility and blue points from DC magnetic relaxation measure-ments.Lower:M (H )hysteresis for 2Dy using an average sweep rate of 3.9mTs À1.Figure 3.Direction of the principal axis of the g -tensor in the ground KD of 2Dy .11447Angew.Chem.Int.Ed.2017,56,11445–114492017Wiley-VCH Verlag GmbH &Co.KGaA,Weinheimsuggesting that this tensor is not axial enough to sufficiently suppress quantum tunneling of magnetization (QTM)within the ground doublet,as observed experimentally.[17]The splitting of the 6H 15/2multiplets in 1Dy and 2Dy was further studied by calculating the decomposition of the SO-RASSI wave functions of the eight lowest KDs into projec-tions onto the j JM J i states,where J =15/2(Table S3).[18]Significantly,in 2Dy each of the sixteen lowest states has a large projection onto one given j JM J i state.The smallest projection is 0.964in the sixth KD with M J =Æ5/2.All the crystal field states of the 6H 15/2multiplet in 2Dy can therefore be assigned to one M J value,and no significant mixing between the states occurs.To our knowledge,this is the closest to a perfectly axial crystal field observed in any molecular lanthanide complex.In contrast,the equatorially coordinated chloride in 1Dy leads to strong mixing between states with different M J projections.Although projections onto the M J =Æ15/2states in the ground doublet are still fairly large (0.909),in the first excited doublet the projection onto the M J =Æ13/2states are only 0.586,and beyond this the states are strongly mixed.Based on the calculations,mechanisms for the relaxation of magnetization in 1Dy and 2Dy can be proposed (Figure 4,Figure S12).[19]In 1Dy ,the matrix elements connecting the M J =Æ15/2states are substantial,hence ground-state QTM is highly efficient and represent the dominant relaxation process.In 2Dy ,the QTM is effectively blocked in the ground doublet and the first two excited doublets.Starting from the ground doublet,the transition matrix element grows roughly an order of magnitude within each following doublet,in agreement with the increasing transverse components of the respective g -tensors.The QTM starts to become non-negligible in the fourth KD,and in the sixth KD it is dominant.The energy of the sixth doublet (1156cm À1)agrees well with the experimentally observed effective barrier height (1277cm À1).The almost perfectly linear temperature depend-ence of t (Figure 2)suggests that Raman processes are not significant above the blocking temperature,and the effective barrier height should correspond to the energy of the highest doublet involved in the relaxation mechanism.The energy ofthe seventh doublet (1270cm À1)is closer to the experimental value than that of the sixth doublet,however,the strong QTM in the sixth doublet makes it extremely unlikely that the relaxation would proceed via any higher doublet.The small deviation between the energy of the sixth doublet and U eff most likely results from neglecting electron correlation outside the 4f orbital space in the CASSCF calculations.In summary,the complex cation [(Cp ttt )2Dy]+(2Dy )gives rise to unprecedented single-molecule magnet properties,including a record anisotropy barrier and,more notably,magnetic blocking temperatures and coercivity that far exceed those described for all previous SMMs.The properties of 2Dy arise from the exceptional magnetic axiality of Dy 3+in the bis(cyclopentadienyl)ligand environment.Theoretical studies of 1Dy and 2Dy have provided clear insight into the origins of the facile QTM in 1Dy and the effective suppression of QTM in 2Dy ,leading to dominant relaxation via the sixth Kramers doublet.Having established a new benchmark in molecular magnetism that pushes the blocking temperature much closer to the symbolic temperature of 77K,the next challenge is to develop new SMMs with properties that exceed those of 2Dy .AcknowledgementsWe thank:the UK EPSRC (Fellowship to RAL,postdoctoral funding to B.M.D.);the European Commission (MSCA Fellowship to F.S.G.);the NSFC (YCC and MLT,projects 21620102002,91422302);the Academy of Finland (funding for A.M.,project 282499);and Prof.H.M.Tuononen (Uni-versity of Jyv äskyl ä)for providing computational resources.Conflict of interestThe authors declare no conflict of interest.Keywords:anisotropy ·cyclopentadienyl ligands ·dysprosium ·organometallic compounds ·single-molecule magnetsHow to cite:Angew.Chem.Int.Ed.2017,56,11445–11449Angew.Chem.2017,129,11603–11607[1]a)J.M.Frost,K.L.M.Harriman,M.Murugesu,Chem.Sci.2016,7,2470;b)P .Zhang,L.Zhang,J.Tang,Dalton Trans.2015,44,3923;c)D.N.Woodruff,R.E.P 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Microstructure and magnetic properties of bulk magnets Nd_14-xFe_76+xCo_3Zr_1B_6x=0,0.5,1 prepar

JOURNAL OF RARE EARTHS,Vol.27,No.6,Dec.2009,p.1023Fou ndation it em:Project supported by t he National Natural Science Foundati on of China (50801049)Cor respondin g aut hor:LIU Ying (E-mail:liuying5536@;Tel.:+86-28-85405332)DOI 6S ()636Microstr ucture and magnetic properties of bulk magnets Nd 14–x Fe 76+x Co 3Zr 1B 6(x=0,0.5,1)prepar ed by spark plasma sinter ingMA Yilong (马毅龙),LIU Ying (刘颖),LI Jun (李军),DU Huilong (杜慧龙),GAO Jing (高静)(College of Materials S cience and Engineering,Sichuan Univers ity,Chengdu 610065,China)Received 24December 2008;revised 26February 2009Abstract:Melt-spun ribbons with nominal composition of Nd 14–x Fe 76+x Co 3Zr 1B 6(x=0,0.5,1)were consolidated into isotropic bulk magnets by spark plasma sintering method.It was found that the Nd content and sintering temperature had significant influence on the density and magnetic properties of thesintered magnets.Homogeneous microstructure and fine grain (50–100nm)wereobtained when sintering below 700°C,and the initial magnetization curve showed that the coercivity was controlled by the pinning mechanism.However,abnormally large grains and inhomogeneous microstructure in magnets were observed after sintering at 750°C,furthermore,the grains were found to be multi-domain structure and the coercivity was mainly controlled by nucleation mechanism.Keywords:spark plasma sintering;NdFeB magnet;magnetic properties;microstructure;rare earthsEver since the technique of melt-spun has been applied in NdFeB and nanograins were gained,powders with highmagnetic properties could be obtained [1–4].Nd-rich melt spun NdFeB ribbons exhibit higher coercivity than ribbon with near-stoichiometric composition (11%–13%Nd).This mainly attributes to the presence of paramagnetic phase at Nd 2Fe 14B grain boundaries.This paramagnetic phase can serve to decouple the individual grains of Nd 2Fe 14B and it is also considered to act as an agent damping the nucleation of the reverse domain.The Nd-rich phase also plays a domi-nant role in densification during sintering due to their low melting point.But on the other hand,remanent magnetic polarization J r decreases with increasing Nd content due to the progressive decoupling of grains which diminishes the effect of exchange interaction [5,6].The densified bulk magnet for practical usage can be ob-tained by hot-pressing melt-spun powders.Spark plasma sintering (SPS)is a new method for producing bulk materi-als by heating the powder sample with DC pulsed current under pressure.Its important advantages over other methods are high sintering speed and the possibility to consolidate powder at relatively lower temperatures,thus,allowing the formation of full-density magnets with high magnetic prop-erties [7–9].Nevertheless,the effect of SPS on magnetic prop-erties and microstructure of NdFeB magnets containing Nd-rich phase is not well understood.Thus,bulk magnet with different Nd contents (13at.%–14at.%)were obtainedby applying SPS under different sintering conditions,and theeffect of sintering temperature and holding time on magnetic properties and microstructure was discussed in this paper.1ExperimentalAlloy ingots with nominal composition of Nd 14–x Fe 76+xCo 3Zr 1B 6(x=0,0.5at%,1at%)prepared by in-duction melting under Ar atmosphere were broken into small pieces,then were melt spun into ribbons in argon at a rolling speed of 30m/s.The ribbons were compacted into isotropic bulk magnet with size of Φ20mm ×10mm after sintering in graphite mold.Fig.1shows the DSC curves of Nd 14Fe 76Co 3Zr 1B 6and Nd 13Fe 77Co 3Zr 1B 6,and it indicates the onset of crystallization close to 580°C,so 580°C is chosen as the lowest sintering temperature.The sintering conditions were as follows:pressure 50MPa,temperature 580–750°C,heating rate 90°C/min and holding time 2–8min.The specimens were cut into Φ10from bulk material for property measurements.The magnetic properties of magnets were measured by AMT-4automatic measuring in-strument of magnetization characteristic (manufactured by Mianyang Shuangji Electronic Company,China)with a maximum applied field of 2T at room temperature after magnetized in a pulsed field of 5T,and the initial magneti-zation curve was obtained by LakeShore7410vibrating sample magnetometer (VSM).The density was measured by:10.101/1002-072108081-1024J OURNAL OF RARE EARTHS,Vol.27,No.6,Dec.2009Fig.1Differential scanning calorimetry of alloy Nd13Fe77Co3Zr1B6(1)and Nd14Fe76Co3Zr1B6(2)Archimedes’method.The microstructure of the specimens was examined using a JSM-5900LV scanning electron mi-croscope(SEM).The phase in the specimens was examined by DX-2000X-ray diffraction with Cu Kαradiation.2Results and discussion2.1The effect of Nd content on magnetic pr oper ties Fig.2shows density and magnetic properties of hot press-ing Nd14Fe76Co3Zr1B6,Nd13.5Fe76.5Co3Zr1B6and Nd13Fe77 Co3Zr1B6alloys as a function of holding time at700°C and sintering temperature with a holding time of5min under a pressure of50MPa.From Fig.2it can be seen that with increasing content of Nd,the density D and intrinsic coer-civity H cj increase under the same sintering conditions;the density of alloy Nd14Fe76Co3Zr1B6is7.52g/cm3at a sinter-ing temperature of680°C,however,alloy Nd13Fe77Co3 Zr1B6has a density of only6.9g/cm3.The Nd-rich phase as-sists densification during sintering,so more Nd-rich phase in the magnets can promote density increment.Magnet con-taining higher Nd content exhibits larger intrinsic coercivity, that is because higher volume fraction of the paramagnetic grain boundary phase(Nd-rich phase)enhances the effect of decoupling of the approximately spherical Nd2Fe14B.For magnets made by powder metallurgy,densification increases remanent magnetization B r.So B r increases with increasing content of Nd due to the increase of density.But when sintered at700°C and held for5min,B r of alloy Nd13.5Fe76.5Co3Zr1B6is higher than alloy Nd14Fe76Co3Zr1B6. The reason is that the increase of density for Nd13.5Fe76.5Co3Zr1B6is larger than N d14Fe76Co3Zr1B6from680 to700°C.Additionally,the volume fraction of the para-magnetic grain boundary phase decreases with reducing Nd content,B r increases because of the increasing exchange coupling and the decreasing dilution of Nd2Fe14B phase.2.2The magnetic propert ies and microstructure Apparently,the density of bulk magnets increases slightly with the increase of holding time,but largely with increasing sintering temperature.This shows that sintering temperature has a larger effect on density than holding time.From Fig.3 it is noted that many voids exist in the interface area be-tween particles in the magnet sintered at580°C,but few voids are observed in the magnets sintered at680°C,which indicates that magnet was densified at680°C.After sintered at750°C,it appears some bright and stripped areas in the contacting areas of the particles as shown in Fig.3(d). Figs.4(a),(b),(c)and(d)are magnified micrographs of Fig.3.It can be found that the grain size of the alloy sintered at580°C is smaller and is about30–60nm;the grains grow up to100nm at680°C;when the sintering temperature is750°C, the grain size is over200nm and inhomogeneous;Fig.4(d) shows grains in the bright striped areas which are abnor-mally large and the maximum size is about2m.The same phenomenon is also observed in magnets sintered at700°C and with holding time more than6min.It can be concluded that the microstructure is homogeneous when sinteredbelowFig.2Density and magnetic properties of hot pressed magnets of amorphous alloys Nd14–x Fe76+x Co3Zr1B6(x=0,0.5,1)as afunction of holding time at700°C(left)and sintering tem-f5()perature with a holding time o min rightMA Y ilong et al.,Microstructure and magnetic properties of bulk magnets Nd 14–x Fe 76+x Co 3Zr 1B 6(x=0,0.5,1)…1025Fig.3SEM micrographs of fracture surfaces of the sintered Nd 14Fe 76Co 3Zr 1B 6alloy at different temperatures(a)580°C;(b)680°C;(c)750°CFig.4Magnified SEM micrographs (a),(b),(c)and A (d)of Fig.3700°C,but nonuniform when sintered at 750°C.The un-even microstructure exists in the sintered magnet because ofpulsed current during sintering.In the SPS process,pulsed electric current flows directly through the sintered materials and generates spark plasma at the particle contacts,so local high temperature is created in the contacting areas of the particles [10].The higher sintering temperature is,the greater working current appears,and the effect of local high tem-perature generated by discharging between particles is larger.Thus,abnormal grain growth is easy to occur in the contact-ing areas of the particles sintered at high temperature.Intrinsic coercivity of these three alloys with different Nd content keeps nearly constant below sintering temperature of 680°C,but drops sharply with the sintering temperature raised to 750°C.Likewise,coercivity decreases when theFig.5XRD of melt spun powders of Nd 14Fe 76Co 3Zr 1B 6alloy (1),sintered at 580°C (2),and at 750°C (3)holding time exceeds 5min.Fig.5shows XRD of amor-phous Nd 14Fe 76Co 3Zr 1B 6alloy and sintered at 580and 750°C for 5min.It indicates that alloy Nd 14Fe 76Co 3Zr 1B 6has been crystallized when sintering at 580°C and is still iso-tropic and only has Nd 2Fe 14B phase when sintering at 750°C.This means that decrease of intrinsic coercivity is only associated with grain growth.For melt-spun magnetic powders containing rich Nd,when the mean grain size is below the threshold (~40nm),the larger the grain size,the smaller the effect of ferromag-netic exchange coupling between nanocrystallites,so B r de-creases and H cj increases;H cj remains constant when the grain size is above the threshold [11].But when the grain size is above the critical grain size of single domain,the coerciv-ity decreases [1,12].For the critical grain size of single domain,Croat et al.[1]estimated a range of 100–160nm for sin-gle-domain particle diameter,and Chapman et al.[13]found that the theoretical value is about 200nm in diameter.The initial magnetic curves of Nd 14Fe 76Co 3Zr 1B 6magnets sintered at different temperatures are shown in Fig.6.With increasing applied magnetic field,the initial magnetization increases slowly due to pinning mechanism,but increases largely and approaches saturation quickly due to nucleation mechanism [14].Therefore,curve (1)in Fig.6indicates that the mechanism of coercivity is pinning;curve (3)shows that the magnetization mechanism is nucleation type.Meanwhile,according to Sun ’s research [12],curve (1)is closer to sin-gle-domain magnetization curve and curve (3)is closer to multi-domain magnetization curve.The change of coercivity1026J OURNAL OF RARE EARTHS,Vol.27,No.6,Dec.2009Fig.6Initial magnetization curve of Nd 14Fe 76Co 3Zr 1B 6alloy sin-tered at 680°C (1),700°C (2)and 750°C (3)mechanism results from grain growth apparently.When the grain size is 100nm,it is still single-domain;but when the grain size is over 200nm,it exceeds the critical size of sin-gle-domain and belongs to multi-domain particle.Thus,the domain wall pinning weakens and the nucleation mechanism dominates.Curve (2)is closer to the combination of curves (1)and (3),w hich indicates that sample sintered at 700°C for 5min is composed of both single and multi-domain grains.When the grain size of magnets sintered at 680°C grows up to 100nm,the grain is still single domain,and coercivity is mainly controlled by pinning mechanism.But when sintered at 750°C,the grain size exceeds 200nm and inhomogeneous,so the stray field increases and the grain changes to multi-domain particles,which lead to decreased intrinsic coercivity.The density of magnets after sintering increases obviously with increasing sintering temperature,and prolonged hold-ing time also improves densification.But on the other hand,the grains of magnets grow up with increasing sintering tem-perature and holding time,grain growth would reduce B r .So B r decreases when sintering temperature is higher than 700°C or the holding time is longer than 5min.The magnetic en-ergy products of the above mentioned three alloys had the same tendency as B r .3ConclusionsAmorphous alloys with nominated composition of Nd 14–x Fe 76+x Co 3Zr 1B 6(x=0,0.5,1)could be crystallized quickly at lower temperature by applying spark plasma sin-tering technique;with increasing Nd content,it was easier to densify the melt-spun ribbons and to increase the intrinsic coercivity H cj obviously;sintering temperature had signifi-cant effect on density and B r than holding time,and with in-creasing temperature,density D and B r increased,after that,B r and H cj decreased due to excessive crystal grain growth.Nd 14Fe 76Co 3Zr 1B 6alloy could be densified after sintering 6°f 5were obtained;with decreasing Nd content,the sintering temperature or holding time should be increased in order to density the magnets.When the sintering temperature was above 700°C,the grain size exceeded 100nm and abnor-mally large grains appeared in the contacting area between the particles;moreover,the multi-domain dominated in the magnets and the coercivity was mainly controlled by nu-cleation mechanism.References:[1]Croat J J,Herbst J F,Lee R W,Pinkerton E E.High energyproduct NdFeB permanent magnets.J.Appl.Phys.,1984,55:2078.[2]Brown David,Ma B M,Chen Z M.Developments in the proc-essing and properties of NdFeB-type permanent magnets.J.Magn.Magn.Mater.,2002,248:432.[3]Chang Y,Pan C,Yu X J,Li W,Lian F Z.Microstructure and magnetic properties of double-phase nanocomposite NdFeB.Journa l of Rare Ear ths,2005,23:270.[4]Zhang S Y,Xu H,Ni J S,Wang H L,Hou X L,Dong Y D.Microstructure refinement and magnetic property enhance-ment for nanocomposite Nd 2Fe 14B/α-Fe alloys by Co and Zr additions.J.Phys.B,2007,393:153.[5]Manaf A,Zhang P Z,Ahmad I,Davies H A,Buckley R A.Magnetic properties and microstructural characterization of isotropic nanocrystalline Fe-Nd-B based alloys.IEEE Trans.Magn.,1993,29:2866.[6]Ahmad I,Davies H A,Buckley R A.The effect of Nd content on the structure and properties of melt spun Nd-rich NdFeB alloys.J.Magn.Magn.Mater.,1996,157/158:11.[7]Yue M,Zhang J X,Tian M,Liu X B.Microstructure and mag-netic properties of isotropic bulk Nd x Fe 94–x B 6(x=6,8,10)nano-composite magnets prepared by spark plasma sintering.J.A ppl.Phys.,2006,99:08B502.[8]Saito T.Magnetic properties of Nd-Fe-Ti-C-B nanocomposite magnets produced by spark plasma sintering method.J.A ppl.Phys.,2006,99:08B522.[9]Saito T,Takeuchi T,Kageyama H.Magnetic properties of Nd-Fe-Co-Ga-B magnets produced by spark plasma sintering method.J.A ppl.Phys.,2005,97:10H103.[10]Wang Y C,Fu Z Y.Study of temperature f ield in spark plasmasintering.Materials Science and Engineering B,2002,90:34.[11]Betancourt R J I,Davies H A.Effect of the grain size on themagnetic properties of nanophase REFeB alloys.J.Magn.Magn.Mater.,2002,246:6.[12]Sun W S,Li S D,Quan M X.The effect of phase constituenton the magnetic properties for melt-spun Nd 15Fe 77B 8ribbons.J.Magn.Magn.Mater.,1997,176:307.[13]Chapman J N,Heyderman L J,Young S,Donnet D M,ZhangP Z,Davies H A.Micromagnetic and microstructural studies of NdFeB by TEM.A cta Metallurgica,1995,33:1807.[14]Zhou S Z,Dong Q F.Super Permanent Magnets-PermanentMagnetic Material of Rare-earth and Iron System.Beijing:Metallurgy Industry Publishing,1999.at 80C or min and the optimum magnetic properties。

武汉理工大学研究生--材料科技英语-课文翻译

GlassIt is well known that glasses play an important role as one of building materials ordinary living products. Advanced and specialty glasses also play important roles in several industries. In the last several years, these materialshave continued to find new applications in the areas of telecommunications, electronics, and biomedical uses. Glass compositions and processing techniques continue to evolve to suit the increasing number of applications. Some of the glass compositions have distinctive properties that make them the most preferred materials for certain applications, such as optical fibers, electronic displays, biocompatible implants, dental posterior materials, and high-performance composites.众所周知，玻璃作为建筑材料普通生活产品之一起着重要的作用。

先进和特种玻璃也在许多行业也起着重要作用。

在过去几年中，这些材料继续在电讯，电子，生物医学领域发现新的应用。

为适应日益剧增的应用，玻璃的组分和加工技术不断发展。

钢铁冶金专业英语词汇

钢铁冶金专业英语词汇目录1 总论 (1)2 采矿 (1)3 选矿 (1)4 冶金过程物理化学 (2)4.1 冶金过程热力学 (2)4.2 冶金过程动力学 (4)4.3 冶金电化学 (5)4.4 冶金物理化学研究方法 (5)5 钢铁冶金 (5)5.1 炼焦 (5)5.2 耐火材料 (6)5.3 碳素材料 (7)5.4 铁合金 (7)5.5 烧结与球团 (7)5.6 高炉炼铁 (8)5.7 炼钢 (10)5.8 精炼、浇铸及缺陷 (12)6 钢铁材料 (14)7 英译汉 (14)'.1 总论采矿mining地下采矿underground mining露天采矿open cut mining, open pit mining, surface mining采矿工程mining engineering选矿（学）mineral dressing, ore beneficiation, mineral processing矿物工程mineral engineering冶金（学）metallurgy过程冶金（学）process metallurgy提取冶金（学）extractive metallurgy化学冶金（学）chemical metallurgy物理冶金（学）physical metallurgy金属学Metallkunde冶金过程物理化学physical chemistry of process metallurgy冶金反应工程学metallurgical reaction engineering 冶金工程metallurgical engineering钢铁冶金（学）ferrous metallurgy, metallurgy of iron and steel有色冶金(学)nonferrous metallurgy真空冶金(学)vacuum metallurgy等离子冶金(学)plasma metallurgy微生物冶金(学)microbial metallurgy喷射冶金(学)injection metallurgy钢包冶金(学)ladle metallurgy二次冶金(学)secondary metallurgy机械冶金(学)mechanical metallurgy焊接冶金(学)welding metallurgy粉末冶金(学)powder metallurgy铸造学foundry火法冶金(学)pyrometallurgy湿法冶金(学)hydrometallurgy电冶金(学)electrometallurgy氯冶金(学)chlorine metallurgy矿物资源综合利用engineering of comprehensive utilization of mineral resources中国金属学会The Chinese Society for Metals中国有色金属学会The Nonferrous Metals Society of China2 采矿采矿工艺mining technology有用矿物valuable mineral冶金矿产原料metallurgical mineral raw materials 矿床mineral deposit特殊采矿specialized mining海洋采矿oceanic mining, marine mining矿田mine field矿山mine露天矿山surface mine地下矿山underground mine矿井shaft矿床勘探mineral deposit exploration矿山可行性研究mine feasibility study矿山规模mine capacity矿山生产能力mine production capacity矿山年产量annual mine output矿山服务年限mine life矿山基本建设mine construction矿山建设期限mine construction period矿山达产arrival at mine full capacity开采强度mining intensity矿石回收率ore recovery ratio矿石损失率ore loss ratio工业矿石industrial ore采出矿石extracted ore矿体orebody矿脉vein海洋矿产资源oceanic mineral resources矿石ore矿石品位ore grade岩石力学rock mechanics岩体力学rock mass mechanics3 选矿选矿厂concentrator, mineral processing plant 工艺矿物学process mineralogy开路open circuit闭路closed circuit流程flowsheet方框流程block flowsheet产率yield回收率recovery矿物mineral粒度particle size粗颗粒coarse particle细颗粒fine particle超微颗粒ultrafine particle粗粒级coarse fraction细粒级fine fraction'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.。

关于Mn3Al块体合金的电子结构计算

2019年1期研究视界科技创新与应用Technology Innovation and Application关于Mn 3Al 块体合金的电子结构计算王俊灏（西南大学物理科学与技术学院，重庆400715）引言自旋电子学器件具有不同于传统半导体器件的优势使它成为21世纪重要的研究方向之一。

传统的电子学器件通常是利用电子的电荷特性，而自旋电子学器件是通过电子的自旋和电荷来进行运输的。

相对于传统电子学器件来说，自旋电子学器件不仅具有更低的耗能、非易失性、更强大的数据储存能力，而且还具有更快速的信息处理能力和集成度高的优质特点。

除此之外，它在磁记录读出磁头、磁传感器、磁性随机存储器等领域有着广泛的应用前景。

尽管自旋电子学器件能够更好地满足科学发展和人类的需要，但是它在实际材料的需求上有着较高的要求。

自旋电子学器件的制作的关键就在于如何能够将不同特征的电子有效的注入到半导体材料中，以此来达到实现自主运输的目的。

正如我们所知的，现在很多的材料做成的自旋电子学器件都只能在低温的环境下运行，这带来了很多的不便。

所以研究能在高居里温度下运行的自旋电子学器件的材料就显得尤为重要了。

研究表明自旋电子学器件的性能和自旋极化率有着密切的联系，如果材料具有高的自旋极化率，也就是说在费米能级附近分别具有自旋向上和自旋向下的电子数目越不平衡，那么自旋电子学器件的性能就越好。

近年来，由于半金属材料的优点，使得它成为了大家研究的热点之一。

1983年，de Groot 及他的团队采用第一摘要：自旋电子学器件在航天、军事等高科技领域，甚至在智能家电、通讯等民用领域都有广泛的利用，因此它也引起了科学家们越来越多的关注。

我们将对D03型Mn 3Al 块体合金的电子结构和磁性利用理论模拟计算方法进行研究。

根据理论计算发现Mn 3Al 合金不仅具有100%的自旋极化率而且还有半金属特性的电子结构。

关于合金磁性计算研究表明它是完全反铁磁性材料。

Cr12MoV表面摩擦学涂层的性能表征

上海大学硕士学位论文Cr12MoV表面摩擦学涂层的性能表征姓名：王君丽申请学位级别：硕士专业：材料加工工程指导教师：施雯20050201．海大学硕士学位论文１．２气相沉积技术气相沉积技术可分为物理气相沉积（ＰｈｙｓｉｃａｌＶａｐｏｒＤｅｐｏｓｉｔｉｏｎ，简称ＰＶＤ）和化学气相沉积（ＣｈｅｍｉｃａｌＶａｐｏｒＤｅｐｏｓｉｔｉｏｎ，简称ＣＶＤ）。

近十几年来，这类沉积技术发展十分迅速。

ＰＶＤ和ＣＶＤ可以制备各种成分和结构的涂层，如图１．１所示．涂层厚度从几个微米到几个毫米，而且还口Ｊ以制各出非常薄的纳米涂层。

与其它涂层技术相比，气相沉积技术应用在模具表面制备硬质、减摩化合物涂层．由于技术上的优越性及涂层的良好特性，越来越引起人们的高度重视。

随着新技术和新工艺的不断研发，气相沉积技术不仅仅用于工具行业（传统是切削工具表而沉积ＴｉＮ），而将成为今后强化各种模具、切削工具和精密机械零件等表面的主要技术之一，有着很广泛的应用前景。

Ｌａｙ口ｎＩ刹妇删图１．１涂层的制各方法及典型的涂层厚度１．２．１物理气相沉积（ＰｖＤ）１．２．１．１物理气相沉积定义及分类物理气相沉积：是在真空条件下，沉积物由固态转变为气态，同时利用辉光放电、弧光放电等物理过程产生等离子体（等离子体是一种电离气体，是离子化了的原子和电子的集合体，整体显中性，它是一种由带电粒子组成的电离状态，称为物质的第四态），在基体表面沉积或反应沉积一层所需的同体薄膜或涂层技上海人学硕士学位论文１．２气相沉积技术气相沉积技术可分为物理气相沉积（ＰｈｙｓｉｃａｌＶａｐｏｒＤｅｐｏｓｉｔｉｏｎ，简称ＰＶＤ）和化学气相沉积（ＣｈｅｍｉｃａｌＶａｐｏｒＤｅｐｏｓｉｔｉｏｎ，简称ＣＶＤ）。

近十几年来，这类沉积技术发展十分迅速。

ＰＶＤ和ＣＶＤ可以制备各种成分和结构的涂层，如图１．１所示．涂层厚度从几个微米到几个毫米，而且还可以制备出非常薄的纳米涂层。

与其它涂层技术相比，气相沉积技术应用在模具表面制备硬质、减摩化合物涂层，由于技术上的优越性及涂层的良好特性，越来越引起人们的高度重视。

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2912IEEE TRANSACTIONS ON MAGNETICS,VOL.42,NO.10,OCTOBER 2006Enhancing Magnetic Properties of Bulk Anisotropic Nd–Fe–B/ -Fe Composite Magnets by ApplyingPowder Coating TechnologiesS.Liu 1,A.Higgins 1,E.Shin 1,S.Bauser 1,C.Chen 1,D.Lee 1,Y .Shen 2,Y .He 2,and M.Q.Huang 3University of Dayton Magnetics Laboratory,Dayton,OH 45469USAFutureTek Corporation,Dayton,OH 45419USAUES Inc.and the Wright Patterson Air Force Base,Dayton,OH 45433USABulk anisotropic composite Nd 14Fe 795Ga 05B 6/-Fe magnets with (BH )max =45–55MGOe were synthesized by compacting Nd–Fe–Ga–B powders coated withthin -Fe layers followed by hot compaction at 600C to 700C and hot deformation (die upsetting)at 850C to 950C with a height reduction of 71%.The coating techniques used include DC and RF sputtering,pulsed laser depo-sition,chemical coating,and electrolytic posite magnets prepared using these techniques demonstrate enhanced intrinsic coercivity and signiﬁcantly improved squareness of intrinsic demagnetization curves.Index Terms—Chemical coating,composite magnet,electrolyte coating,interface exchange coupling,nanograin,Nd 2Fe 14B,pulsed laser deposition,sputtering.I.I NTRODUCTIONRESEARCH on nanocomposite rare earth permanent magnet materials started with the Philips group in 1988[1].Because the nanograin structures were created by annealing amorphous alloys obtained by melt spinning [1]–[3]or mechan-ical alloying [4],[5],only isotropic powders or ribbons could be made.Synthesizing bulk anisotropic nanograin composite magnets remained a great challenge [6],[7].Recently,bulk anisotropicNd–Fe–B/-Fe and Nd–Fe–B/Fe–Co composite magnets were synthesized via hot com-paction of a mixture of a melt-spun Nd–Fe–B powder andan -Fe or Fe–Co powder,followed by die upsetting [8].The magnetically soft phase in these magnets is quite large,up to40m.It is obvious that if the soft phase could be signiﬁcantly reduced in size and highly dispersed throughout the magnet,then the interaction between the soft and hard phases should be enhanced,and thus,magnetic performance of the composite magnets can be further improved.It seems that the above objective could be reached by usingﬁner -Fe or Fe–Co powders.However,experiments showed thatﬁne -Fe or Fe–Co powders agglomerate during processing and are prone to pick up oxygen,both making it difﬁcult to ob-tain composite magnets with improved magnetic performance.This paper reports a new approach to reduce the size and im-prove the distribution of the soft phase.II.E XPERIMENTIn this study,various coating technologies were applied to coat melt-spun micrometer-sized Nd–Fe–B powder par-ticles withthin -Fe or Fe–Co layers.The melt-spunNdFeGaB contains a minor Nd-rich phase that isDigital Object Identiﬁer 10.1109/TMAG.2006.879905essential to obtain the desired crystallographic texture during the hot deformation process [9].The coating technologies used were as follows.•1)DC and RF sputtering:An -Fe target was used,and a rotating powder sample holder was used to obtain more uniform coated layers.The sputtering was performed under an Ar atmosphere with the chamber pressure of 2.0Pa.•Pulsed laser deposition (PLD:An -Fe target and anNd:Y Al O(nm)laser were used with 340mJ/pulse and 10Hz.The chamber pressurewasPa.For both sputtering and PLD,the deposition time varied from 15min up to 20h.•Chemical (electroless)coating:A solution ofFeSO 7H O at 0.1mol/l was used as the solute,with NaH PO at 0.4mol/l added as a reducing agent andNaC HO at 0.3mol/l added as a complexing agent.The solution pH value was 5to 8;the temperature was 20C to 50C;and the coating time was from 15min to 2h.•Electrolytic coating:Solutes used wereFeSO 7H O at 0.3mol/l with an addition ofMgSO 4H O at 0.3mol/l.The solution pH value was 2to 3;temperature was 25C to 30C;and the coating time was 0.5to 2h.The anode and cathode materialswere -Fe and aluminum,respec-tively.The cathode current density was 0.5to 5A/dm .It is estimated that for sputtering,PLD,and chemical coating,the soft phase fraction is around 2–3%,while for electrolytic coating around 3–5%.The coated powders were hot compacted at 550C to 650CunderPa for a total cycle time of about 2min using a hot press with inductive heating,followed by die upsetting at850C to 950C underaroundPa for 4–8min with a height reduction of 71%.A scanning electron microscope/energy dispersive spectra (SEM/EDS)was used to observe and analyze the coated powder0018-9464/$20.00©2006IEEELIU et al.:ENHANCING MAGNETIC PROPERTIES OF BULK ANISOTROPIC Nd –Fe –B/-Fe COMPOSITE MAGNETS2913Fig.1.SEM micrograph of a coated surface of an Nd –Fe –B powder particle after DC sputtering for 20h.Fig.2.High-resolution SEM micrograph of the coated surface of an Nd –Fe –B powder particle after electrolytic coating for 1h.particles.SEM and a transvere electromagnetic micrograph (TEM)were used to observe microstructures and identify different phases of the composite magnets.X-ray diffraction was used to analyze grain alignment,and a hysteresisgraph was used to characterize room temperature magnetic properties of bulk composite magnets.In addition,the oxygen contents of the coated powders were analyzed following LECO ISO 9001procedures.III.R ESULTS AND D ISCUSSIONSThe SEM observations showed that in all cases the coated layers were not smooth and uniform,but had rough and mottled morphologies.Fig.1shows a SEM micrograph of a coated sur-face of an Nd-Fe –B powder particle after DC sputtering for 20h.After coating using various technologies,the coated material is believed to be in an amorphous condition.Fig.2is a high-res-olution SEM micrograph of the coated surface of an Nd –Fe –B powder particle after electrolytic coating for 1h.It seems from the morphology of the as-coated Fe that the coated Fe is in an amorphouscondition.Fig.3.Demagnetization curves of a composite Nd Fe Ga B / -Femagnet prepared by sputtering for 20h.Fig. 4.TEM micrograph of the Nd –Fe –B phase of an Nd Fe Ga B / -Fe magnet prepared using electrolytic coating.Among the various coating technologies used,the elec-trolytic coating showed the highest deposition rate,while chemical coating demonstrated the lowest.Further,with chemical coating,only about one-fourth to one-third of the powder particles are actually coatedwith -Fe.On the other hand,sputtering,PLD,and chemical coating are associated with the lowest oxygen ing these methods,only 0.04–0.06wt%oxygen was detected —very close to the orig-inal oxygen content of uncoated powders.Electrolytic coating had the highest oxygen pickup,with oxygen contents in the range of 0.1–0.3wt%.Using the various coating technologies,the bulk anisotropicNd –Fe –B/-Fe composite magnets reachedBH–MGOe with enhanced intrinsic coercivity and signi ﬁcantly im-proved squareness of intrinsic demagnetization curves,as com-pared with composite magnets prepared by mechanical blending of the powders [8].Fig.3shows the demagnetization curves of aNdFeGaB/-Fe composite magnet prepared by DC sputtering for 20h,hot compacting at 630C for 2min,and die upsetting at 930C for 4min.A set of “iso-energy-product ”contour curves are plotted in Fig.3to help estimatingBH of the intrinsic demagnetization curve.Similar magnetic proper-ties were obtained in composite magnets prepared by chemical coating for only 1h.The electrolytic coating resulted in thickcoated layers;however,the correspondingBHvalues were less than 50MGOe,due to relatively high oxygen pickup during the coating process.As a comparison,the typical properties of coating-free magnets prepared under the same conditionsarekG,kOe,andBH 40MGOe.Fig.4shows a TEM micrograph of a specimen cut parallel to the deformation direction,showing the elongated and aligned2914IEEE TRANSACTIONS ON MAGNETICS,VOL.42,NO.10,OCTOBER2006Fig.5.Selected area electron diffraction of a perpendicular section of anNd FeGa B / -Fe magnet prepared using electrolytic coating.grains of the matrix phase in anNdFeGaB/-Femagnet prepared by electrolytic coating for 1h.The elongated grains have a thickness of about 100to 200nm and length of a few hundred nanometers.Some large grains were also observed.With further reduction of the grain size through opti-mized processing,magnetic performance,especially coercivity,can be signi ﬁcantly improved.Fig.5is a selected area electron diffraction pattern of anNdFeGaB/-Fe magnet prepared via electrolytic coating for 1h and cut perpendicular to the deformation di-rection,showing crystallographic direction [001]of tetragonal NdFe B superimposed with rings of amorphous or very ﬁne grains ofbody-centered-cubic -Fe.The existence of an amorphous phase after exposure to an elevated temperature of around 900C for a short period of time was also observed in previous experiments.The x-ray diffraction analyses revealed variations in the de-gree of grain alignment of the upper and lower faces of the spec-imens,even withBHin 50-MGOe range.This phenom-enon is believed to be related to the fact that only unidirectional stress was applied in the die upsetting process.Synthesizing bulk anisotropic nanograin composite magnets by utilizing powder coating technologies is still in its very early stage of development.A better coating technology with an improved deposition rate and lower oxygen pickup is yet to be developed.However,this approach is a step forward toward creating the desired microstructure,i.e.,a highly dispersedmagnetically soft phase,suchas -Fe or Fe –Co,is uniformly distributed in a nanograin magnetically hard phase,such as Nd –Fe –B.Adding a magnetically soft phase into Nd –Fe –B certainly en-hances its magnetization,but decreases its coercivity.The re-duction of the coercivity depends not only on the amount of the soft phase added,but strongly depends on the size and dis-tribution of the soft phase.Obviously,a very ﬁne and highly dispersed soft phase will result in a very large hard/soft inter-facial area,thus,leading to a more effective hard/soft interface exchange coupling,which will minimize the reduction in coer-civity.In addition,this effect will allow more magnetically soft phase to be added into a composite magnet,leading to higher magnetization and improved magnetic performance.A CKNOWLEDGMENTThis work was supported in part by the Defense Advanced Research Projects Agency through the Of ﬁce of Naval Research under Contract N00014-03-01-0636and through the Air Force Research Laboratory under Contract F33615-01-2-2166and in part by the Department of Energy under Contract DE-FG02-05ER86242.Magnequench MQU-F42powder was used as the base-line reference material.R EFERENCES[1]K.H.J.Buschow,D.B.De Mooij,and R.Coehoorn,“Metastable fer-romagnetic materials for permanent magnets,”J.Less-Common Metals ,vol.145,pp.601–611,1988.[2]R.Coehoorn,D.B.de Mooij,and C.de Waard,“Melt spun permanentmagnets materials containing Fe B as the main phase,”J.Magn.Magn.Mater ,vol.80,p.101,1989.[3] A.Manaf,R.A.Buckley,and H.A.Davies,“New nanocrystalline high-remanence Nd –Fe –B alloys by rapid solidi ﬁcation,”J.Magn.Magn.Mater ,vol.128,p.302,1993.[4]J.Wecker,M.Katter,and L.Schultz,“Mechanically alloyed Sm-Co ma-terials,”J.Appl.Phys ,vol.69,p.6058,1991.[5]S.K.Chen,J.L.Tsai,and T.S.Chin,“Nanocomposite Sm Co /Copermanent magnets by mechanical alloying,”J.Appl.Phys.,vol.79,p.5964,1996.[6]Z.Chen,Y .Zhang,M.Daniil,H.Okumura,G.C.Hadjipanayis,and Q.Chen,“Review of rare earth nanocomposite magnets,”in Proc.16th Int.Workshop on REM ,vol.1,2000,p.449.[7]K.H.Chen,Z.Q.Jin,J.Li,G.Kennedy,Z.L.Wang,N.N.Thadhani,H.Zeng,S.-F.Cheng,and J.P.Liu,“Bulk nanocomposite magnets pro-duced by dynamic shock compaction,”J.Appl.Phys.,vol.96,p.1276,2004.[8] D.Lee,S.Bauser,A.Higgins,C.Chen,S.Liu,M.Q.Huang,Y .G.Peng,and ughlin,“Bulk anisotropic composite rare earth magnets,”J.Appl.Phys.,vol.99,pp.516–517,May 2006.[9]J.J.Croat,“Current status of rapidly solidi ﬁed Nd –Fe –B permanentmagnets,”in Proc.11th Int.Workshop on REM ,vol.1,S.G.Sankar,Ed.,1990.Manuscript received March 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