Crystal growth and morphology of substituted gadolinium gallium garnet
02-晶体生长(结晶学与矿物学)
第二章 晶体生长理论
2-1 晶体的形成方式
(a)
(b)
第二章 晶体生长理论
2-2 晶核的形成
晶体生长过程的第一步，就是形成晶核。
成核是一个相变过程，即在母液相中形成固相小晶芽，这一相变 过程中体系自由能的变化为： ΔG= ΔGv +ΔGs ΔGs为新相形成时新旧相界面的 表面能，ΔGv为新相形成时的体系 自由能 rc为体系自由能由升高到降低转 变时所对应的晶核半径值——临界 半径 只有当r>rc时， ΔG下降，晶核才 能稳定存在。 也就是说，晶核的形成，一方 面由于体系从液相转变为内能更小 的晶体相而使体系自由能下降，另 一方面又由于增加了液 - 固界面而使 体系自由能升高。
第二章 晶体生长理论
2-3 晶体生长模型 2.螺旋生长理论模型 (screw growth)
（Frank）等人（1949，1951）的实验证实：气相结晶时，1%的过饱和度 即可。另外，发现实际晶体总是存在台阶位错。
第二章 晶体生长理论
2-4 晶面的发育 1布拉维法则 晶体上的实际晶面平行于面网密度大的面网，这 就是布拉维法则(law of Bravais)。
discretediffractionpatternquasicrystalznmghodiffractionanysolidhavingessentiallydiscretediffractiondiagram212223242526gs为新相形成时新旧相界面的表面能gv为新相形成时的体系自由能为体系自由能由升高到降低转变时所对应的晶核半径值临界半径只有当rrg下降晶核才能稳定存在
国际晶体学联合会最近建议把晶体定义为衍射图谱呈现明 确图案的固体（any solid having an essentially discrete diffraction diagram）来代替原先的微观 空间呈现周期性结构的定义。
拟晶体的名词解释
拟晶体的名词解释拟晶体（quasicrystal）是一种具有非周期性长程有序结构的固体材料。
它的发现颠覆了传统晶体学中“周期性结构”的概念，为材料科学带来了新的研究方向和挑战。
拟晶体的特殊结构和性质使其成为了科学界关注的焦点，并在多个领域展示了潜在的应用前景。
一、拟晶体的发现拟晶体最初在1982年由丹麦物理学家丹尼斯·谢伯诺夫斯基（Dan Shechtman）首次发现。
当时，他对铝－锰－合金进行高温冷却实验，意外观察到了一种不规则的、五角星形的模式。
根据传统晶体学的观点，这种非周期性的结构理论上是不可能存在的，因此遭遇到了科学界的质疑和反对。
然而，经过进一步实验证实和理论分析，谢伯诺夫斯基却成功证明了这种新型结构的存在，并于2011年获得了诺贝尔化学奖。
这个重大发现引起了广泛的兴奋和研究热潮，也为拟晶体的研究奠定了基础。
二、拟晶体的结构特点拟晶体的结构具有多面体对称性，一般表现为五角形、六角形、十二面体等不规则形态，而不像晶体那样有明显的周期性。
拟晶体中的原子或分子排列方式遵循一定的规则，但这种规则并不像晶体那样精确地重复。
拟晶体的结构包含了不同长度尺度的重复单元，这使得它具备了多样的物理和化学性质。
三、拟晶体的物理性质拟晶体的非周期性结构赋予了它独特的物理性质。
首先，拟晶体具有良好的电学导性，可用于制备高性能的电子器件。
其次，拟晶体在光学领域也有广泛的应用，拥有宽波长范围内的光学散射效应，可以用于制备不同波长的光学器件。
此外，拟晶体还具备较好的热导性、力学性能和磁学性质，为材料科学和工程领域提供了新的研究方向。
四、拟晶体的应用前景由于其特殊的结构和性质，拟晶体在多个领域展示了潜在的应用前景。
在材料科学领域，拟晶体可用于制备高性能的金属合金和陶瓷材料，具备优异的力学性能、耐热性和电学导性。
在能源领域，拟晶体也被用于改善材料的热导性，为热能转换和热管理提供新的解决方案。
此外，拟晶体还在催化、药物输送和生物材料等领域展示了独特的应用潜力。
布里奇曼法LaBr3Ce晶体生长
晶体生长成果
毛胚晶体 3850mm3
加工晶体 1010 10mm3
晶体闪烁性能
Intensity
X射线激发
90
X-ray excited emission spectrum
80
70
LaBr3:Ce Testing conditions：
PMT: 600V
60
X-ray tube: 50kV
50
CsI:Tl
celabr极易潮解氧化2labrlaobrhcllabr非常容易开裂100严重解理热膨胀各向异性突出定向生长自发成核技术p63ma796c451晶体生长的问题晶体生长工艺原料预处理抽真空封装晶体生长水氧含量1ppm真空度1pa温度梯度2030ccm1英寸labr
为什么是LaBr3:Ce
光输出 能量分辨率 衰减时间 （Ph/MeV） (@662keV) (ns)
LaBr3非常容易开裂
P63/m a=7.96 c=4.51
2LaOBr+2Br2 LaOBr+HCl
（100）严重解理 热膨胀各向异性突出
定向生长 自发成核技术
c
b
a
晶体生长工艺
原料预处理
抽真空封装
晶体生长
水、氧含量 < 1ppm
真空度 ~1pa
温度梯度20~30C/cm
晶体生长成果
1英寸LaBr3:Ce单晶生长技术已经成熟
90
80 70 60
3 LaBr3(Ce)： 12X12X10mm
3 CsI(Tl)： 12.5X12.5X8mm
50
40
30
20
10
0 0
100 200 300 400 500 600 700 800 900 1000
晶体学基础-球面投影
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晶体投影要解决的问题？ -晶向（面）间关系的表达
1.晶面的夹角
P1与P2面的夹角－－ OP1与OP2夹角φ： 过P1，P2与球心O做一大圆， P1P2的弧度。
Байду номын сангаас
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（三）乌氏网（Wulff net)
刻度球的
极射赤平投影面 度量
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乌氏网的应用
两极点之间角度测量
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♣在投影图上任一个极点对应的密勒指数的确定：
一个晶面在空间的取向可以由它的法线与三个晶轴 [100]、[010]及[001]的夹角确定。
h:k:l=acosρ:bcosσ:ccosτ
注意： 量度两个极点间的角度，
是过两个极点的经线来量度。
计算机绘制任意投影面的标准极图。
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晶体结构对称性：
材料科学基础
Fundamentals of Materials Science
晶体学基础-球面投影
22:14
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材料科学与工艺 的基础理论
第1章 原子结构与结合键
Atomic Structure and binding bond
第2章 晶体学基础 Basis of Crystallography 第3章 晶体结构 Crystal Structure 第4章 晶体缺陷 Crystal defects 第5章 非晶体与准晶结构 Amorphous and
Quasicrystal Structure
第6章 相图 Phase Diagram 第7章 固体扩散 Solid Diffusion 第8章 凝固与结晶 Solidification and Crystallization 第9章 烧结与聚合 Sintering and Polymerization 第10章 固态 相变 Solid Phase Transformation
如何根据外观辨识单一手性晶体？
大 学 化 学Univ. Chem. 2024, 39 (3), 78收稿：2023-09-01；录用：2023-10-19；网络发表：2023-11-13*通讯作者，Email:***************.cn•专题• doi: 10.3866/PKU.DXHX202309004 如何根据外观辨识单一手性晶体？王海英1,*，苏纪豪21川北医学院医学影像四川省重点实验室，四川南充 637000 2厦门大学化学化工学院，福建 厦门 361005摘要：有些消旋体结晶过程中的自发拆分会导致对映异构体单晶呈现不同的外观状态。
本文总结并列举了根据外观辨识单一手性晶体的四种方式，包括：半面体面、宏观形态、偏光颜色和表面形貌。
这些“以貌取人”的方法为探究手性化合物的结晶行为提供了重要的工具和见解。
关键词：自发拆分；半面体面；宏观形态；偏光颜色；表面形貌中图分类号：G64；O6How to Visually Identify Homochiral CrystalsHaiying Wang 1,*, Andrew C.-H. Sue 21 Sichuan Key Laboratory of Medical Imaging, North Sichuan Medical College, Nanchong 637000, Sichuan Province, China.2 College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian Province, China.Abstract: During the crystallization process of certain racemic compounds, spontaneous resolution can lead to distinctive external appearances of enantiomeric crystal forms. This article offers a comprehensive overview and delineates four methods for identification, namely, examining hemihedral faces, assessing macromorphology, employing circular polarization, and analyzing surface topography. These identification techniques serve as invaluable tools and viewpoints for studying the crystallization behavior of chiral compounds, holding significant potential across diverse applications in pharmaceutical production, materials science, and chemical synthesis.Key Words: Spontaneous resolution; Hemihedral faces; Macromorphology; Circular polarization;Surface topography手性(Chirality)是指物体与其镜像图形无法完全重合的性质[1]。
晶体异质外延的生长方式
晶体异质外延（Epitaxy）的生长方式包括但不限于：
1. 气相外延：气相外延是通过控制气体源的成分、温度、压力等参数，使材料原子在衬底表面沉积并结晶。
这种方法可以用于生长多种材料，包括硅、镓、锗等。
2. 液相外延：液相外延是一种基于溶液的生长方法，通过将溶液中的材料沉积在晶体衬底表面来实现生长。
在生长过程中，溶液中的材料原子逐渐结晶并沉积在衬底上。
这种方法可以用于生长多种材料，包括硅、镓、锗等。
通过改变溶液的成分、温度和压力等参数，可以控制晶体生长的形状、尺寸和取向等属性。
此外，还有其他外延技术，如分子束外延（MBE）和化学气相沉积（CVD）。
这些技术可用于生长单晶薄膜，具有广泛应用。
以上信息仅供参考，建议咨询相关晶体学专家获取准确和专业的解答。
Spontaneous_precipitation_of_struvite_from_aqueous_solutions
1. Introduction Struvite [MgNH (PO ) ) 6H O] is often found as a constituent of scale deposits on pipe walls and in equipment of anaerobic digestion in wastewater treatment industry [1]. In wastewater treatment plants, struvite crystallization from the supernatant of the anaerobically digested sludge is a signi"cant
0022-0248/00/$ - see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 0 2 4 8 ( 0 0 )ouropoulos, P.G. Koutsoukos / Journal of Crystal Growth 213 (2000) 381 } 388
* Corresponding author. Institute of Chemical Engineering and High Temperature Chemical Processes, P.O. Box 1414, GR-26500 Patras, Greece. Tel.: #30-61-997265; fax: #30-61993255. E-mail address: pgk@iceht.forth.gr (P.G. Koutsoukos).
CrystalGrowth-lecture3
Dr. Y.L. Du
School of Materials Science and Engineering
yldu@ Autumn semester,2012
Crystal growth methods
drawbacks
•confined growth (crucible may induce stresses during cooling) •difficult to observe seeding and growing processes •changes in natural convection as the melt is depleted •delicate crucible and seed preparation, sealing, etc.
Growth from melt:
1. Bridgman technique 2. Czochralski technique 3. Kyropoulos technique 4. Zone melting technique 5. Verneuil technique
Growth from solution:
Jan Czochralski (1885 - 1953)
characteristics:
• charge and seed are separated at start • no material is added or removed (conservative process) • charge is held at temperature slightly above melting point • crystal grows as atoms from the melt adhere to the seed
TbAl_3_BO_3_4晶体生长和磁光性质的研究
TbAl 3(BO 3)4晶体生长和磁光性质的研究付聪 卢俊业 宋财根 庄乃锋 陈建中*福州大学化学化工学院 福州 350108E-mail ：j.z.chen@摘要：本文分别采用导模法和助熔剂法对TbAl 3(BO 3)4晶体进行生长研究探索，寻求其成为可见光波段法拉第磁光材料的可能性。
TbAl 3(BO 3)4多晶原料采用球磨工艺结合高温固相法合成，根据DSC －TGA 谱图确定固相合成的烧结工艺。
并对原料进行XRD 和磁化率的测定，XRD 数据与标准谱图一致，其磁化率为2.46E-5。
磁化强度M 与磁场强度H 的关系表示为：H M χ=，式中χ为物体的磁化率。
在磁场的作用下，物质的电磁特性(如磁导率、磁化强度、磁畴结构等)会发生变化，使光波在其内部的传输特性(如偏振状态、光强、相位、传输方向等)也随之发生变化的现象称为磁光效应，因此预测TbAl 3(BO 3)4晶体有成为良好的磁光材料的可能性。
通过调整模块形状、温度梯度、晶体拉速、助熔剂（K 2Mo 3O 10-B 2O 3）浓度等生长工艺条件，生长出的TbAl 3(BO 3)4物化性能稳定，不潮解。
在室温下测量了晶体400-1500nm 波段的透射光谱，其透过率达到80%以上。
结合实验分析表明，晶体的颜色和包裹主要是助熔剂的影响。
关键词:晶体生长；导模法；TbAl 3(BO 3)4；磁光晶体参考文献[1] N.I. Leonyuk and T.I. Leonyuk Growth and characterization of RM 3(BO 3)4 crystals Prog. Crystal Growth and Charact. 1995,31, 179-278.[2] 杨新波等，导模法生长晶体研究进展[J]，硅酸盐学报，2008，36（S1）：222-227.基金项目：国家自然科学基金（50772023）255。
大角度晶界的英语
大角度晶界的英语Abstract:Macroscopic grain boundaries (MGBs) are a critical feature in polycrystalline materials, significantly influencing mechanical properties, thermal conductivity, and electrical conductivity. This paper delves into the characteristics, formation mechanisms, and the impact of MGBs on the performance of materials, with a focus on their rolein various applications.1. IntroductionGrain boundaries are interfaces between two crystalline grains in a polycrystalline solid. When the misorientation between grains is significant, these boundaries can be considered macroscopic, exhibiting distinct properties that differ from those of the bulk material. The study of MGBs is essential for understanding material behavior and optimizing performance in engineering applications.2. Characteristics of Macroscopic Grain BoundariesMacroscopic grain boundaries are characterized by their misorientation angles, which are typically greater than 15 degrees. They can be classified into several types based on the crystallographic relationship between the grains they separate:- Twin boundaries: Where the misorientation is a mirror reflection across the boundary plane.- Coincidence site lattice (CSL) boundaries: Where a high density of lattice points from both grains coincide at the boundary.- General boundaries: With no specific crystallographic relationship, these are the most common type.3. Formation MechanismsMGBs can form during various material processing techniques:- Recrystallization: After severe deformation, grains can grow, leading to the formation of MGBs.- Grain growth: During annealing, larger grains can consume smaller ones, resulting in increased misorientations at the boundaries.- Phase transformations: Changes in crystal structure during phase transitions can create MGBs.4. Impact on Material PropertiesThe presence of MGBs has a profound effect on the properties of polycrystalline materials:- Strength: MGBs can impede dislocation motion, increasing the material's strength.- Ductility: They can act as sites for crack initiation, affecting ductility.- Conductivity: MGBs can scatter electrons and phonons, reducing thermal and electrical conductivity.5. ApplicationsUnderstanding MGBs is crucial for optimizing materials in various applications:- Metalworking: Controlling grain size and boundary characteristics can enhance the mechanical properties of metals.- Electronics: In semiconductor devices, MGBs can influence carrier mobility and device performance.- Ceramics: MGBs in ceramics can affect fracture toughness and thermal shock resistance.6. Experimental Techniques for Studying MGBsSeveral experimental methods are used to study MGBs:- Scanning electron microscopy (SEM): Can reveal the morphology of MGBs.- Transmission electron microscopy (TEM): Provides detailed information on the atomic structure of boundaries.- Electron backscatter diffraction (EBSD): Allows for the determination of grain orientation and the identification of MGBs.7. Computational ModelingComputational techniques, such as molecular dynamics and phase-field modeling, are used to simulate MGB formation and behavior:- Molecular Dynamics (MD): Offers insights into atomic-scale processes at MGBs.- Phase-Field Modeling: Can predict the evolution of grain structures and boundary characteristics during processing.8. ConclusionMacroscopic grain boundaries play a critical role in determining the properties of polycrystalline materials. Understanding their characteristics, formation, and impact is essential for the development of advanced materials with tailored properties for specific applications. Future research should focus on developing new techniques to control MGBs and on multiscale modeling to predict their effects on material behavior.References1. Hull, D., & Bacon, D. J. (2011). Introduction to Dislocations (5th ed.). Butterworth-Heinemann.2. Humphreys, F. J., & Hatherly, M. (2004). Recrystallization and Related Annealing Phenomena (2nd ed.). Elsevier.3. Gottstein, G. (2002). Physical Foundations ofMaterials Science. Springer.4. Randle, V. (2017). Grain Boundary CharacterDistribution and its Applications. CRC Press.This document provides a comprehensive overview of macroscopic grain boundaries, discussing theircharacteristics, formation, and impact on material properties, as well as the experimental and computational techniques used to study them. It concludes with the significance of MGBs in material applications and the importance of future researchin this area.。
CrystGrowthDes晶体生长英文文献
An Infinite Two-Dimensional Hybrid Water-Chloride Network,Self-Assembled in a Hydrophobic Terpyridine Iron(II)MatrixRicardo R.Fernandes,†Alexander M.Kirillov,†M.Fátima C.Guedes da Silva,†,‡Zhen Ma,†JoséA.L.da Silva,†João J.R.Fraústo da Silva,†andArmando J.L.Pombeiro*,†Centro de Química Estrutural,Complexo I,Instituto Superior Técnico,TU-Lisbon,A V.Ro V isco Pais,1049-001Lisbon,Portugal,and Uni V ersidade Luso´fona de Humanidades e Tecnologias,A V.doCampo Grande,376,1749-024,Lisbon,PortugalRecei V ed October18,2007;Re V ised Manuscript Recei V ed January7,2008ABSTRACT:An unprecedented two-dimensional water-chloride anionic{[(H2O)20(Cl)4]4–}n network has been structurally identified in a hydrophobic matrix of the iron(II)compound[FeL2]Cl2·10H2O(L)4′-phenyl-2,2′:6′,2″-terpyridine).Its intricate relief geometry has been described as a set of10nonequivalent alternating cycles of different sizes ranging from tetra-to octanuclear{[(H2O)x(Cl)y]y–}z(x) 2–6,y)0–2,z)4–6,8)fragments.In contrast to the blooming research on structural characterizationof a wide variety of water clusters in different crystalline materials,1much less attention has been focused on the identification anddescription of hybrid hydrogen-bonded water assemblies with othersolvents,small molecules,or counterions.1c,2In particular,thecombination of chloride ions and water is one of the most commonlyfound in natural environments(e.g.,seawater or sea-salt aerosols),and thus the investigation of water-chloride interactions has beenthe object of numerous theoretical studies.3However,only recentlya few water-chloride associates incorporated in various crystalmatrixes have been identified and structurally characterized,4,5including examples of(i)discrete cyclic[(H2O)4(Cl)]–,4a[(H2O)4(Cl)2]2–,4b and[(H2O)6(Cl)2]2–4c clusters,and(ii)variousone-or two-dimensional(1D or2D)hydrogen-bonded networksgenerated from crystallization water and chloride counterionswith{[(H2O)4(Cl2)]2–}n,5b{[(H2O)6(Cl)2]2–}n,5b[(H2O)7(HCl)2]n,5c{[(H2O)11(Cl)7]7–}n,5d{[(H2O)14(Cl)2]2–}n,5e{[(H2O)14(Cl)4]4–}n,5aand{[(H2O)14(Cl)5]5–}n5f compositions.These studies are alsobelieved to provide a contribution toward the understanding of thehydration phenomena of chloride ions in nature and have importancein biochemistry,catalysis,supramolecular chemistry,and designof crystalline materials.5In pursuit of our interest in the self-assembly synthesis andcrystallization of various transition metal compounds in aqueousmedia,we have recently described the[(H2O)10]n,6a(H2O)6,6b and[(H2O)4(Cl)2]2–4b clusters hosted by Cu/Na or Ni metal-organicmatrixes.Continuing this research,we report herein the isolationand structural characterization of a unique2D water-chlorideanionic layer{[(H2O)20(Cl)4]4–}n within the crystal structure of thebis-terpyridine iron(II)compound[FeL2]Cl2·10H2O(1′)(L)4′-phenyl-2,2′:6′,2″-terpyridine).Although this compound has beenobtained unexpectedly,a search in the Cambridge StructuralDatabase(CSD)7,8points out that various terpyridine containinghosts tend to stabilize water-chloride associates,thus also sup-porting the recognized ability of terpyridine ligands in supra-molecular chemistry and crystal engineering.9,10Hence,the simple combination of FeCl2·2H2O and L in tetrahydrofuran(THF)solution at room temperature provides the formation of a deep purple solid formulated as[FeL2]Cl2·FeCl2·5H2O(1)on the basis of elemental analysis,FAB+-MS and IR spectroscopy.11This compound reveals a high affinity for water and,upon recrystallization from a MeOH/H2O(v/v)9/1)mixture,leads to single crystals of1′with a higher water content,which have been characterized by single-crystal X-ray analysis.12The asymmetric unit of1′is composed of a cationic[FeL2]2+ part,two chloride anions,and10independent crystallization water molecules(with all their H atoms located in the difference Fourier map),the latter occupying a considerable portion of the crystal cell. The iron atom possesses a significantly distorted octahedral coordination environmentfilled by two tridentate terpyridine moieties arranged in a nearly perpendicular fashion(Figure S1, Supporting Information).Most of the bonding parameters within [FeL2]2+are comparable to those reported for other iron compounds*To whom correspondence should be sent.Fax:+351-21-8464455.E-mail: pombeiro@ist.utl.pt.†Instituto Superior Técnico.‡Universidade Luso´fona de Humanidades eTecnologias.Figure 1.Perspective representations(arbitrary views)of hybrid water-chloride hydrogen-bonded assemblies in the crystal cell of1′; H2O molecules and chloride ions are shown as colored sticks and balls, respectively.(a)Minimal repeating{[(H2O)20(Cl)4]4–}n fragment with atom numbering scheme.(b)Nonplanar infinite polycyclic2D anionic layer generated by linkage of four{[(H2O)20(Cl)4]4–}n fragments(a) represented by different colors;the numbers are those of Table1and define the10nonequivalent alternating cycles of different size.2008310.1021/cg7010315CCC:$40.75 2008American Chemical SocietyPublished on Web02/08/2008bearing two terpyridine ligands.13The most interesting feature of the crystal structure of 1′consists in the extensive hydrogen bonding interactions of all the lattice–water molecules and chloride coun-terions (Table S1,Supporting Information),leading to the formation of a hybrid water -chloride polymeric assembly possessing minimal repeating {[(H 2O)20(Cl)4]4–}n fragments (Figure 1a).These are further interlinked by hydrogen bonds generating a nonplanar 2D water -chloride anionic layer (Figure 1b).Hence,the multicyclic {[(H 2O)20(Cl)4]4–}n fragment is con-structed by means of 12nonequivalent O–H ···O interactions with O ···O distances ranging from 2.727to 2.914Åand eight O–H ···Cl hydrogen bonds with O ···Cl separations varying in the 3.178–3.234Årange (Table S1,Supporting Information).Both average O ···O [∼2.82Å]and O ···Cl [∼3.20Å]separations are comparable to those found in liquid water (i.e.,2.85Å)14and various types of H 2O clusters 1,6or hybrid H 2O -Cl associates.4,5Eight of ten water molecules participate in the formation of three hydrogen bonds each (donating two and accepting one hydrogen),while the O3and O7H 2O molecules along with both Cl1and Cl2ions are involved in four hydrogen-bonding contacts.The resulting 2D network can be considered as a set of alternating cyclic fragments (Figure 1b)which are classified in Table 1and additionally shown by different colors in Figure 2.Altogether there are 10different cycles,that is,five tetranuclear,three pentanuclear,one hexanuclear,and one octa-nuclear fragment (Figures 1b and 2,Table 1).Three of them (cycles 1,2,and 6)are composed of only water molecules,whereas the other seven rings are water -chloride hybrids with one or two Cl atoms.The most lengthy O ···O,O ···Cl,or Cl ···Cl nonbonding separations within rings vary from 4.28to 7.91Å(Table 1,cycles 1and 10,respectively).Most of the cycles are nonplanar (except those derived from the three symmetry generated tetrameric fragments,cycles 1,2,and 4),thus contributing to the formation of an intricate relief geometry of the water -chloride layer,possessing average O ···O ···O,O ···Cl ···O,and O ···O ···Cl angles of ca.104.9,105.9,and 114.6°,respectively (Table S2,Supporting Information).The unprecedented character of thewater -chloride assembly in 1′has been confirmed by a thorough search in the CSD,7,15since the manual analysis of 156potentially significant entries with the minimal [(H 2O)3(Cl)]–core obtained within the searching algorithm 15did not match a similar topology.Nevertheless,we were able to find several other interesting examples 16of infinite 2D and three-dimensional (3D)water -chloride networks,most of them exhibiting strong interactions with metal -organic matrixes.The crystal packing diagram of 1′along the a axis (Figure 3)shows that 2D water -chloride anionic layers occupy the free space between hydrophobic arrays of metal -organic units,with an interlayer separation of 12.2125(13)Åthat is equivalent to the b unit cell dimension.12In contrast to most of the previously identified water clusters,1,6water -chloride networks,5,16and extended assemblies,1c the incorporation of {[(H 2O)20(Cl)4]4–}n sheets in 1′is not supported by strong intermolecular interactions with the terpyridine iron matrix.Nevertheless,four weak C–H ···O hydrogen bonds [avg d (D ···A))3.39Å]between some terpyridine CH atoms and lattice–water molecules (Table S1,Figure S2,Supporting Information)lead to the formation of a 3D supramolecular framework.The thermal gravimetric analysis (combined TG-DSC)of 117(Figure S3,Supporting Information)shows the stepwise elimination of lattice–water in the broad 50–305°C temperature interval,in accord with the detection on the differential scanning calorimetryTable 1.Description of Cyclic Fragments within the {[(H 2O)20(Cl)4]4–}n Network in 1′entry/cycle numbernumber of O/Cl atomsformula atom numberingschemegeometry most lengthy separation,Åcolor code a 14(H 2O)4O3–O4–O3–O4planar O3···O3,4.28light brown 24(H 2O)4O6–O7–O6–O7planar O7···O7,4.42light gray 34[(H 2O)3(Cl)]-O2–O4–O3–Cl2nonplanar O4···Cl2,4.66blue 44[(H 2O)3(Cl)]-O6–O7–O9–Cl1nonplanar O7···Cl1,4.61green 54[(H 2O)2(Cl)2]2-O9–Cl1–O9–Cl1planar Cl ···Cl1,4.76pink 65(H 2O)5O2–O4–O3–O10–O8nonplanar O2···O10,4.55red75[(H 2O)4(Cl)]-O1–O5–O7–O9–Cl1nonplanar O7···Cl1,5.25pale yellow 85[(H 2O)4(Cl)]-O1–O5–Cl2–O8–O10nonplanar O10···Cl2,5.29orange 96[(H 2O)4(Cl)2]2-O2–O8–Cl2–O2–O8–Cl2nonplanar Cl2···Cl2,7.12yellow 108[(H 2O)6(Cl)2]2-O1–O10–O3–Cl2–O5–O7–O6–Cl1nonplanarCl1···Cl2,7.91pale blueaColor codes are those of Figure 2.Figure 2.Fragment of nonplanar infinite polycyclic 2D anionic layer in the crystal cell of 1′.The 10nonequivalent alternating water or water -chloride cycles are shown by different colors (see Table 1for color codes).Figure 3.Fragment of the crystal packing diagram of 1′along the a axis showing the intercalation of two water -chloride layers (represented by space filling model)into the metal -organic matrix (depicted as sticks);color codes within H 2O -Cl layers:O red,Cl green,H grey.Communications Crystal Growth &Design,Vol.8,No.3,2008783curve(DSC)of three major endothermic processes in ca.50–170, 170–200,and200–305°C ranges with maxima at ca.165,190, and280°C,corresponding to the stepwise loss of ca.two,one, and two H2O molecules,respectively(the overall mass loss of9.1% is in accord with the calculated value of9.4%for the elimination of allfive water molecules).In accord,the initial broad and intense IRν(H2O)andδ(H2O)bands of1(maxima at3462and1656cm–1, respectively)gradually decrease in intensity on heating the sample up to ca.305°C,while the other bands remain almost unchangeable. Further heating above305°C leads to the sequential decomposition of the bis-terpyridine iron unit.These observations have also been supported by the IR spectra of the products remaining after heating the sample at different temperatures.The elimination of the last portions of water in1at temperatures as high as250–305°C is not commonly observed(although it is not unprecedented18)for crystalline materials with hosted water clusters,and can be related to the presence and extensive hydrogen-bonding of chloride ions in the crystal cell,tending to form the O–H(water)···Cl hydrogen bonds ca.2.5times stronger in energy than the corresponding O–H(water)···O(water)ones.5a The strong binding of crystallization water in1is also confirmed by its FAB+-MS analysis that reveals the rather uncommon formation of the fragments bearing from one tofive H2O molecules.11The exposure to water vapors for ca.8h of an almost completely dehydrated(as confirmed by weighing and IR spectroscopy)product after thermolysis of1(at250°C19for 30min)results in the reabsorption of water molecules giving a material with weight and IR spectrum identical to those of the initial sample1,thus corroborating the reversibility of the water escape and binding process.In conclusion,we have synthesized and structurally characterized a new type of2D hybrid water-chloride anionic multicyclic {[(H2O)20(Cl)4]4–}n network self-assembled in a hydrophobic matrix of the bis-terpyridine iron(II)complex,that is,[FeL2]Cl2·10H2O 1′.On the basis of the recent description and detailed analysis of the related{[(H2O)14(Cl)4]4–}n layers5a and taking into consideration that the water-chloride assembly in1′does not possess strong interactions with the metal-organic units,the crystal structure of 1′can alternatively be defined as an unusual set of water-chloride “hosts”with bis-terpyridine iron“guests”.Moreover,the present study extends the still limited number5of well-identified examples of large polymeric2D water-chloride assemblies intercalated in crystalline materials and shows that terpyridine compounds can provide rather suitable matrixes to stabilize and store water-chloride aggregates.Further work is currently in progress aiming at searching for possible applications in nanoelectrical devices,as well as understanding how the modification of the terpyridine ligand or the replacement of chlorides by other counterions with a high accepting ability toward hydrogen-bonds can affect the type and topology of the hybrid water containing associates within various terpyridine transition metal complexes.Acknowledgment.This work has been partially supported by the Foundation for Science and Technology(FCT)and its POCI 2010programme(FEDER funded),and by a HRTM Marie Curie Research Training Network(AQUACHEM project,CMTN-CT-2003-503864).The authors gratefully acknowledge Prof.Maria Filipa Ribeiro for kindly running the TG-DSC analysis,urent Benisvy,Dr.Maximilian N.Kopylovich,and Mr.Yauhen Y. Karabach for helpful discussions.Supporting Information Available:Additionalfigures(Figures S1–S3)with structural fragments of1′and TG-DSC analysis of1, Tables S1and S2with hydrogen-bond geometry in1′and bond angles within the H2O-Cl network,details for the general experimental procedures and X-ray crystal structure analysis and refinement,crystal-lographic informationfile(CIF),and the CSD refcodes for terpyridine compounds with water-chloride aggregates.This information is available free of charge via the Internet at .References(1)(a)Mascal,M.;Infantes,L.;Chisholm,J.Angew.Chem.,Int.Ed.2006,45,32and references therein.(b)Infantes,L.;Motherwell,S.CrystEngComm2002,4,454.(c)Infantes,L.;Chisholm,J.;Mother-well,S.CrystEngComm2003,5,480.(d)Supriya,S.;Das,S.K.J.Cluster Sci.2003,14,337.(2)(a)Das,M.C.;Bharadwaj,P.K.Eur.J.Inorg.Chem.2007,1229.(b)Ravikumar,I.;Lakshminarayanan,P.S.;Suresh,E.;Ghosh,P.Cryst.Growth Des.2006,6,2630.(c)Ren,P.;Ding,B.;Shi,W.;Wang,Y.;Lu,T.B.;Cheng,P.Inorg.Chim.Acta2006,359,3824.(d)Li,Z.G.;Xu,J.W.;Via,H.Q.;Hu,mun.2006,9,969.(e)Lakshminarayanan,P.S.;Kumar,D.K.;Ghosh,P.Inorg.Chem.2005,44,7540.(f)Raghuraman,K.;Katti,K.K.;Barbour,L.J.;Pillarsetty,N.;Barnes,C.L.;Katti,K.V.J.Am.Chem.Soc.2003,125,6955.(3)(a)Jungwirth,P.;Tobias,D.J.J.Phys.Chem.B.2002,106,6361.(b)Tobias,D.J.;Jungwirth,P.;Parrinello,M.J.Chem.Phys.2001,114,7036.(c)Choi,J.H.;Kuwata,K.T.;Cao,Y.B.;Okumura,M.J.Phys.Chem.A.1998,102,503.(d)Xantheas,S.S.J.Phys.Chem.1996,100,9703.(e)Markovich,G.;Pollack,S.;Giniger,R.;Cheshnovsky,O.J.Chem.Phys.1994,101,9344.(f)Combariza,J.E.;Kestner,N.R.;Jortner,J.J.Chem.Phys.1994,100,2851.(g)Perera, L.;Berkowitz,M.L.J.Chem.Phys.1991,95,1954.(h)Dang,L.X.;Rice,J.E.;Caldwell,J.;Kollman,P.A.J.Am.Chem.Soc.1991, 113,2481.(4)(a)Custelcean,R.;Gorbunova,M.G.J.Am.Chem.Soc.2005,127,16362.(b)Kopylovich,M.N.;Tronova,E.A.;Haukka,M.;Kirillov,A.M.;Kukushkin,V.Yu.;Fraústo da Silva,J.J.R.;Pombeiro,A.J.L.Eur.J.Inorg.Chem.2007,4621.(c)Butchard,J.R.;Curnow,O.J.;Garrett,D.J.;Maclagan,R.G.A.R.Angew.Chem.,Int.Ed.2006, 45,7550.(5)(a)Reger,D.L.;Semeniuc,R.F.;Pettinari,C.;Luna-Giles,F.;Smith,M.D.Cryst.Growth.Des.2006,6,1068and references therein.(b) Saha,M.K.;Bernal,mun.2005,8,871.(c) Prabhakar,M.;Zacharias,P.S.;Das,mun.2006,9,899.(d)Lakshminarayanan,P.S.;Suresh,E.;Ghosh,P.Angew.Chem.,Int.Ed.2006,45,3807.(e)Ghosh,A.K.;Ghoshal,D.;Ribas,J.;Mostafa,G.;Chaudhuri,N.R.Cryst.Growth.Des.2006,6,36.(f)Deshpande,M.S.;Kumbhar,A.S.;Puranik,V.G.;Selvaraj, K.Cryst.Growth Des.2006,6,743.(6)(a)Karabach,Y.Y.;Kirillov,A.M.;da Silva,M.F.C.G.;Kopylovich,M.N.;Pombeiro,A.J.L.Cryst.Growth Des.2006,6,2200.(b) Kirillova,M.V.;Kirillov,A.M.;da Silva,M.F.C.G.;Kopylovich, M.N.;Fraústo da Silva,J.J.R.;Pombeiro,A.J.L.Inorg.Chim.Acta2008,doi:10.1016/j.ica.2006.12.016.(7)The Cambridge Structural Database(CSD).Allen, F.H.ActaCrystallogr.2002,B58,380.(8)The searching algorithm in the ConQuest Version1.9(CSD version5.28,August2007)constrained to the presence of any terpyridinemoiety and at least one crystallization water molecule and one chloride counter ion resulted in43analyzable hits from which40compounds contain diverse water-chloride aggregates(there are29and11 examples of infinite(mostly1D)networks and discrete clusters, respectively).See the Supporting Information for the CSD refcodes.(9)For a recent review,see Constable,E.C.Chem.Soc.Re V.2007,36,246.(10)For recent examples of supramolecular terpyridine compounds,see(a)Beves,J.E.;Constable,E.C.;Housecroft,C.E.;Kepert,C.J.;Price,D.J.CrystEngComm2007,9,456.(b)Zhou,X.-P.;Ni,W.-X.;Zhan,S.-Z.;Ni,J.;Li,D.;Yin,Y.-G.Inorg.Chem.2007,46,2345.(c)Shi,W.-J.;Hou,L.;Li,D.;Yin,Y.-G.Inorg.Chim.Acta2007,360,588.(d)Beves,J.E.;Constable,E.C.;Housecroft,C.E.;Kepert,C.J.;Neuburger,M.;Price,D.J.;Schaffner,S.CrystEngComm2007,9,1073.(e)Beves,J. E.;Constable, E. C.;Housecroft, C. E.;Neuburger,M.;Schaffner,mun.2007,10,1185.(f)Beves,J.E.;Constable,E.C.;Housecroft,C.E.;Kepert,C.J.;Price,D.J.CrystEngComm2007,9,353.(11)Synthesis of1:FeCl2·2H2O(82mg,0.50mmol)and4′-phenyl-2,2′:6′,2″-terpyridine(L)(154mg,0.50mmol)were combined in a THF (20mL)solution with continuous stirring at room temperature.The resulting deep purple suspension was stirred for1h,filtered off,washed with THF(3×15mL),and dried in vacuo to afford a deep purple solid1(196mg,41%).1exhibits a high affinity for water and upon recrystallization gives derivatives with a higher varying content of crystallization water.1is soluble in H2O,MeOH,EtOH,MeCN, CH2Cl2,and CHCl3.mp>305°C(dec.).Elemental analysis.Found: C52.96,H3.76,N8.36.Calcld.for C42H40Cl4Fe2N6O5:C52.42,H4.19,N8.73.FAB+-MS:m/z:835{[FeL2]Cl2·5H2O+H}+,816784Crystal Growth&Design,Vol.8,No.3,2008Communications{[FeL2]Cl2·4H2O}+,796{[FeL2]Cl2·3H2O–2H}+,781{[FeL2]Cl2·2H2O+H}+,763{[FeL2]Cl2·H2O+H}+,709{[FeL2]Cl}+,674 {[FeL2]}+,435{[FeL]Cl2}+,400{[FeL]Cl}+,364{[FeL]–H}+,311 {L–2H}+.IR(KBr):νmax/cm–1:3462(m br)ν(H2O),3060(w),2968 (w)and2859(w)ν(CH),1656(m br)δ(H2O),1611(s),1538(w), 1466(m),1416(s),1243(m),1159(w),1058(m),877(s),792(s), 766(vs),896(m),655(w),506(m)and461(m)(other bands).The X-ray quality crystals of[FeL2]Cl2·10H2O(1′)were grown by slow evaporation,in air at ca.20°C,of a MeOH/H2O(v/v)9/1)solution of1.(12)Crystal data:1′:C42H50Cl2FeN6O10,M)925.63,triclinic,a)10.1851(10),b)12.2125(13),c)19.5622(19)Å,R)76.602(6),)87.890(7),γ)67.321(6)°,U)2180.3(4)Å3,T)150(2)K,space group P1j,Z)2,µ(Mo-K R))0.532mm-1,32310reflections measured,8363unique(R int)0.0719)which were used in all calculations,R1)0.0469,wR2)0.0952,R1)0.0943,wR2)0.1121 (all data).(13)(a)McMurtrie,J.;Dance,I.CrystEngComm2005,7,230.(b)Nakayama,Y.;Baba,Y.;Yasuda,H.;Kawakita,K.;Ueyama,N.Macromolecules2003,36,7953.(c)Kabir,M.K.;Tobita,H.;Matsuo,H.;Nagayoshi,K.;Yamada,K.;Adachi,K.;Sugiyama,Y.;Kitagawa,S.;Kawata,S.Cryst.Growth Des.2003,3,791.(14)Ludwig,R.Angew.Chem.,Int.Ed.2001,40,1808.(15)The searching algorithm in the ConQuest Version1.9(CSD version5.28,May2007)was constrained to the presence of(i)at least onetetranuclear[(H2O)3(Cl)]–ring(i.e.,minimal cyclic fragment in our water-chloride network)with d(O···O))2.2–3.2Åand d(O···Cl) )2.6–3.6Å,and(ii)at least one crystallization water molecule andone chloride counter ion.All symmetry-related contacts were taken into consideration.(16)For2D networks with the[(H2O)3(Cl)]–core,see the CSD refcodes:AGETAH,AMIJAH,BEXVIJ,EXOWIX,FANJUA,GAFGIE, HIQCIT,LUNHUX,LUQCEF,PAYBEW,TESDEB,TXCDNA, WAQREL,WIXVUU,ZUHCOW.For3D network,see the CSD refcode:LUKZEW.(17)This analysis was run on1since we were unable to get1′in a sufficientamount due to the varying content of crystallization water in the samples obtained upon recrystallization of1.(18)(a)Das,S.;Bhardwaj,P.K.Cryst.Growth.Des.2006,6,187.(b)Wang,J.;Zheng,L.-L.;Li,C.-J.;Zheng,Y.-Z.;Tong,M.-L.Cryst.Growth.Des.2006,6,357.(c)Ghosh,S.K.;Ribas,J.;El Fallah, M.S.;Bharadwaj,P.K.Inorg.Chem.2005,44,3856.(19)A temperature below305°C has been used to avoid the eventualdecomposition of the compound upon rather prolonged heating.CG7010315Communications Crystal Growth&Design,Vol.8,No.3,2008785。
Polymorphs 多晶体
Title：Polymorphs Practical1.Introduction：Crystallization is formation of crystal from saturated solution including two steps，nucleation and growth of crystal.，. It is commonly used to separate solids from liquid. During the process ，not all the crystal have the same size and shape. Once the solution is not supersaturated any more，the crystallization is completed. Crystal will be formed as an unstable morphology first and then transfers into the stable morphology.The atom and molecule is tend to form the most stable stage of by arrangement which means that under different conditions such as temperature, the crystal may be formed in different morphologies which is called polymorph. Polymorphism is the existence of different morphologies of crystal that has same compound but different arrangement of molecule during the crystallization process. It also includes solvates and amorphs. Different polymorph has different physical and chemical properties like melting point, chemical reactivity, apparent solubility, dissolution rate, optical and electrical properties, vapour pressure and density.The crystal habit determines the external shape(needle，plates or prism). Many factors affect the crystal habit such as temperature ，level of supersaturation，rate of cooling/agitation, solvent polarity, nature of impurities, concentration, viscosity.During the process, there are many things need to be considered:1. Nucleation and the rate of growth2. Control of process parameter →the kind of product polymorph.3. The level of supersaturation→most difficult to control.4. The temperature. Sometimes the optimum temperature for nucleation is different with the temperature for growth of crystal.The APIs (active pharmaceutical ingredients) of drugs are mainly crystal. The physical properties of crystal are mainly determined by the molecule internal arrangement. The interaction force and internal arrangement of the molecule directly affects the solids. There are many factors that can influence on the crystal such as size，production process，reactivity，toxicity，bioavailability .When the crystal has polymorph，it is necessary to have a research on the variability and reproducibility.During the pharmaceutical process，some properties of Polymorphism can directly affect the quality and process ability of drug like stability，dissolution，and bioavailability. Any changes of process conditions will affect the crystal habit，such as synthesis condition and storage condition. It is essential to control the size and purity of products by the minimum cost though the all production process. Continuous Crystallizer and Batch Crystallizer have been used.Polymorphism has effects on the pharmaceutical properties in several ways such as bioavailability, stability (both chemical and physical), process factors (Hygroscopicity, bulk, mechanical and rheological properties, ease of isolation, filtration and drying),In chemical production, there are three aspect need to be put attention.1.Solid handlingIf the polymorph are different →the shape，size and density of polymorph are different. It will be difficult to separate.2.DryingIf there remain a large amount of solvent，it is hard to achieve uniform product. It will also lengthen the time need to dry which is waste of energy. 3.Activity and StabilityPolymorph has different solubility. It can’t be heating to dissolve because some will be charred on the side of vessel→Intermediate will dissolve slower which affect its reactivity →too much solvent will be absorbed →hard to agitate.It is necessary to investigate the polymorph of crystal at regular intervals before pharmaceutical process. Although the certain form have been manufactured for many years，it is possible to form another more stable morph. It is needed to determine their physical and chemical properties, thermodynamic stability and kinetics of interconversion to identify the reproducibility and variability of drugs. There are several ways to check the polymorph，like observation，melting point under microscope，suspension/heating, solvent of crystallization changes, DSC, IR, X-ray, NMR, TGA.2. Objective：1.To find the effects of impurities on crystal nucleation and growth.2.To identify the parameters that affects the crystal physical properties.3.Discussion3.1 Paracetamol：Figure1. The structure of paracetamol，metacetamol，acetanilide. Metacetamol and acetanilide act as impurities.3.1.1 Microscopy analysis:The Microscopy graphs come from A1, A6,A2 respectively.Figure.2 The crystal possess a monoclinic lattice. It means that without any impurities，paracetamol tend to be orthorhombic structure .Figure. 3 It is remain the monoclinic shape of crystal. But it is obvious that the size of paracetamol with 4 % metacetamol is much smaller than the pure paracetamol. Metacetamol has effects on the size of crystal but litte effect on the shape of crystal.Figure.4 The crystal possess a orthorhombic lattice while the size is larger than the pure paracetamol. The impurity acetanilide is has effect on the size of crystal.3.1.2 Melting Point AnalysisThe factors that affect the melting point.：1.The melting point is mainly decided by the lattice energy. There are threefactors that affect the lattice energy which is the intermolecular force（van der vaals force），the structure of molecule and the type of lattice.2.The structure of paracetamol is more symmetry →It is good for orderlymolecule arrangement. →The melting point is higher. The metacetamol is less symmetry and has lower melting point.3.If hydrogen bonds exist ，the melting point will increase. A primary feature ofthe paracetamol crystal is hydrogen bonding which account for 30% of the total lattice energy, which affects the melting point largely. Acetanilide that is no OH Group doesn’t offer a proton to the existing hydrogen bonding. →low melting point. Metacetamol has an OH group, allow the hydrogen-bonding network to be preserved.→less melting point decrease. [1]The results seem that many of them had deviations, which may come from:1. Misoperation of thermometer：Thermometer didn’t put on the right place(not close to the sample but close to the heating source). As a result，Melting points of some group were too high or too low.3.1.3 IR analysis:The IR spectra of pure paracetamol，paracetamol-metacetamol and paracetamol-acetanilide are from Group 5，Group 4 ，Group 4 respectively last year.From the spectra，It is obvious that the chemical shift is close so IR can’t distinguish the paracetamol, paracetamo-metacetamol，paracetamol-acetanilide.Theoretically，paracetamol and metacetamol have the same function groups and similar structure when acetanilide is lack of –OH. It is hard to distinguish the mixture of them.3.1.4 NMR analysisFigure.5.the sturcure of Paracetamol(the left), and metacetamolto C5,C7 is ortho to OH ，so they are upfield.[2] The structure of the paracetamol is symmetry that explain that only 5 H peaks.From the two H-NMRs , It is obvious that H-NMR can easily distinguish the isomer of paracetamol .3.2 MetronidazoleFigure. 6. The structure of metronidazole, C6H9N3 M.W.=171.163.2.1 Melting point analysis：Some groups did n’t get crystal may because too much solvent.The objective of the experiment is to find the effect of different solvents and the dissolved temperature on the melting point of crystal at different temperature.According to the melting point of groups from Moodle.Polarity[3]: Water(10.2)＞HCl(0.1N) ＞Ethanol(5.2) ＞Methanol(5.1) ＞Dioxane(4.8) ＞Ethyl acetate(4.4) ＞2-Propanol(4) = THF(4)＞Butanol(4) ＞DCM(3.1) = Dichloromethane(3.1) ＞Isopropyl acetateSome results may be unreliable; like that the melting point of B9 DCM is different from it of B1 DCM.2-propanole methanol Ethanol℃160-165 142-151 150-154melting pointFrom the table, it indicates that1. The dissolved temperature has slight effect on the melting point.2. The polarity has slight effect on the melting point. The higher the polarity, the higher the melting point.3.2.2 IR analysis:Compared the spectra of Group 4 and 7，the deviations of the most of the peaks are within 1cm-1. They have similar polarity and both them have –OH group →strong –OH group⬆ affect the hydrogen bonding between solute molecule ⬇→the melting point⬇Compared the spectra of Group 7 and 12, the shifts of the same function groups are different. Ethanol has strong –OH group →less hydrogen bonding →low melting point.In conclusion，solvent has a great effect on the crystal habit of metronidazole. 4. Conclusion4.1 Conclusion of paracetamol experiment:The experiment found the effect of different impurities (metacetamol, acetanilide) on lattice types and melting points. IR spectra was failed to find the differences while NMR can distinguish the metacetamol and paracetamol. Microscopy graphs provided the evidence that impurities may affect the growth (size and the shape) of crystal. Melting point data also directly showed that with the impurities, the melting point will increase in different degrees.4.2 Conclusion of metronidazole experiment:The experiment explored the effect of different solvent/solvent system on the melting point of metronidazole crystal. The measurement of melting point and IR all presented that solvents have a great effect on the melting point though polarity and hydrogen bonding.5. Reference1.[1][2] Claire Tompson, Martyn C.Davies, Clive J. Roberts, (21st Jan 2004)‘Theeffects of additives on the growth and morphology paracetamol(acetaminophen) crystals” J Interational journal of pharmaceuticals.280 2004 137-1502.[3] US Pharmacopeia。
晶体生长理论
界面生长理论
粗糙化相变理论：1951年，Burton、Leamy、 Eerden等提出，存在一个温度，在此温度以上， 界面由基本光滑转变为粗糙，晶体呈线性生长； 并且上述结论在Temkin模型之外成立。
层生长理论
层生长理论是论述在晶核的光滑表面上生长一层原子面时，质点在界 面上进入晶格座位的最佳位臵是具有三面凹入角的位臵。质点在此位 臵上与晶核结合成键放出的能量最大。因为每一个来自环境相的新质 点在环境相与新相界面的晶格上就位时，最可能结合的位臵是能量上 最有力的位臵，即结合成键时应该是成键数目最多，是放出能量最大 的位臵。所以晶体在理想情况下生长时，先长一条行列，然后长相邻 的行列。在长满一层面网后，再开始长第二层面网。层生长理论认为： 晶体的生长是质点面网一层接一层地不断向外平行移动的结果。
界面生长理论
完整光滑突变界面模型：1927年由W．Kossel 提出。认为晶体是理想完整的，并且从原子或 分子的层次来看，界面在原子层次上没有凸凹 不平的现象，固相与流体相之间是突变的。
界面生长理论
非完整光滑界面模型：1949年，F．C．Frank 提出，晶体是理想不完整的，其中必然存在位 错。一个纯螺型位错和光滑的奇异面相交，在 晶面上会产生一个永不消失的台阶源，在生长 过程中，台阶将逐渐变成螺旋状，使晶面不断 向前推移。
有粗糙点的光滑平面生长模拟
晶体生长中，凹陷处比较容易沉积质点。相比 较光滑的平面，如果有粗糙的地方，那么，会 比较方便质点的沉积。
粗糙平面生长模拟
在粗糙的表面上，凹陷之处比较多，二维、三 维凹角可以为沉积的质点提供更多的附着点。
台阶生长模拟
晶体不会在平整的表面上进行沉积，而是沿着 台阶向前推进，铺满一层之后，一层一层的生 长。
药物结晶中的经典与非经典结晶路径
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钛宝石晶体的泡生法生长和闪烁发光性能
第50卷第4期2021年4月人㊀工㊀晶㊀体㊀学㊀报JOURNAL OF SYNTHETIC CRYSTALS Vol.50㊀No.4April,2021钛宝石晶体的泡生法生长和闪烁发光性能王庆国1,刘㊀波1,罗㊀平1,唐慧丽1,吴㊀锋1,康㊀森2,段金柱3,王勤峰3,徐㊀军1(1.同济大学物理科学与工程学院,上海㊀200092;2.天通银厦新材料有限公司,银川㊀750001;3.天通控股股份有限公司,海宁㊀314412)摘要:采用泡生法生长了115kg 级大尺寸钛宝石(TiʒAl 2O 3)晶体,晶体外形完整无开裂,制备了口径达ϕ300mm 的高质量大口径钛宝石单晶样品㊂在X 射线和α粒子激发下测试了晶体的闪烁发光性能㊂结果表明,TiʒAl 2O 3晶体的闪烁发光包含近红外和近紫外发光㊂近红外发光来源于Ti 3+特征发射,效率较高,衰减时间慢㊂近紫外发光来源于Ti 局域激子发光和F +心发光,具有较快的衰减时间,其光输出与掺杂导致的自吸收有关㊂α粒子激发下,光产额达到1130.5pe /MeV,其中快成分光产额为29.6pe /MeV㊂关键词:钛宝石;单晶生长;泡生法;闪烁发光性能中图分类号:O78㊀㊀文献标志码:A ㊀㊀文章编号:1000-985X (2021)04-0762-06Crystal Growth and Scintillation Luminescence Properties of TiʒAl 2O 3Crystals Grown with Kyropoulos MethodWANG Qingguo 1,LIU Bo 1,LUO Ping 1,TANG Huili 1,WU Feng 1,KANG Sen 2,DUAN Jinzhu 3,WANG Qinfeng 3,XU Jun 1(1.School of Physics and Engineering,Tongji University,Shanghai 200092,China;2.TDG Yinxia New Material Co.,Ltd.,Yinchuan 750001,China;3.TDG Holding Co.,Ltd.,Haining 314412,China)Abstract :Large-sized TiʒAl 2O 3crystals with the weight of 115kg were grown successfully by Kyropoulos method.The grown crystals have complete shape without any rge Ti ʒAl 2O 3single crystal sample with diameter of 300mm was prepared.The scintillation luminescence properties of the grown crystals were tested under the X-ray and αparticle excitation.The results show that the scintillation luminescence of TiʒAl 2O 3crystals include near infrared band and near ultraviolet band.The near infrared emission comes from the characteristic emission of Ti 3+,which has high efficiency and slow decay time.The near ultraviolet emission comes from Ti-localized exciton emission and F +center,which has the fast decay time.The light output is related to the self-absorption caused by Ti-doping.Under the excitation of the αparticles,the light yield reaches up to 1130.5pe /MeV,and the fast component is 29.6pe /MeV.Key words :TiʒAl 2O 3;single crystal growth;Kyropoulos method;scintillation luminescence property ㊀㊀收稿日期:2021-04-07㊀㊀基金项目:上海蓝宝石单晶工程技术研究中心项目(14DZ2252500)㊀㊀作者简介:王庆国(1983 ),男,山东省人,博士,工程师㊂E-mail:qgwang@ ㊀㊀通信作者:徐㊀军,博士,教授㊂E-mail:xujun@0㊀引㊀㊀言钛宝石(TiʒAl 2O 3)晶体是当今世界上公认最具有应用价值的宽带可调谐激光晶体,其可调谐波段范围在700~1000nm,是目前调谐范围最宽的激光晶体之一[1],通过啁啾脉冲放大(CPA)技术,可以实现小于10fs 的激光脉冲输出,在高能物理㊁环境污染物检测㊁军事国防㊁激光光谱学等领域具有广泛的应用[2-3]㊂暗物质测量涉及弱相互作用重粒子的测量,待测事件极为稀少,因此要求探测材料具有极低的天然放射性本底,与其他常用闪烁体(例如LYSO 等)相比,蓝宝石(Al 2O 3)具有非常低的放射性本底,是重要的暗物质探㊀第4期王庆国等:钛宝石晶体的泡生法生长和闪烁发光性能763㊀测候选材料㊂蓝宝石具有很低的低温热容量,是优异的低温声子探测器材料,已经在CRESST实验中得到验证[4],如果能够同时获得闪烁发光信息,则可以采用蓝宝石材料构造出声子-闪烁复合探测器,为暗物质的研究带来极大便利㊂钛宝石晶体中Ti离子掺杂可以在蓝宝石晶体中引入Ti局域激子发光,是重要的快成分发光来源㊂因此,钛宝石晶体作为一种快闪烁材料,其闪烁发光性能也引起科学家的广泛研究[5-8]㊂超大尺寸钛宝石长晶和超精密加工成为制约钛宝石在超快激光装置和电磁量能器装置中进一步发展应用的主要因素㊂有关大尺寸钛宝石的生长已有近40年的研究历史,已报道的生长方法有提拉法(Czochralski method,Cz)[9-10]㊁热交换法(heat exchanger method,HEM)[11-12]㊁温度梯度法(temperature gradient technology,TGT)[13]及水平定向凝固法(horizontal directional solidification,HDS)[14]等㊂依托蓝宝石产业的发展,泡生法已经是当前综合成本最低㊁长晶质量最高㊁单体晶体最大的蓝宝石长晶方式,特别是国内天通控股股份有限公司采用自主研发的石墨加热和碳毡保温热场技术,已经能够实现单颗700kg的纯蓝宝石晶体生长,为大尺寸钛宝石的生长奠定了基础㊂国际上法国里昂第一大学的Lebbou课题组也开展了泡生法生长大尺寸钛宝石的研究[15-18],采用钼坩埚在Ar保护气氛或真空环境下生长了晶体质量5~33kg㊁口径100~230mm的钛宝石晶体㊂相比纯蓝宝石晶体,钛宝石晶体生长的难点主要体现在以下几点:首先是Ti3+在蓝宝石中分凝系数很低(约0.16),并存在很严重的掺杂均匀性问题(即分凝偏析),生长大尺寸高浓度掺杂均匀的钛宝石单晶一直是国内外研究的热点和难点问题;其次,由于Ti3+不稳定,极易被氧化为Ti4+,从而增加晶体在红外波段的吸收影响其光学质量,但通常晶体生长采用的原材料又是TiO2,在钛宝石长晶过程中Ti3+和Ti4+共存,从而高温氢气退火是大尺寸钛宝石使用前必须要经历的一道工艺流程;此外,钛离子掺入后,使Al2O3熔体的黏度显著增加,熔体对流减缓,导致熔体气泡不易排除,且长晶周期大大加长,提高了其长晶的难度㊂本文中,通过三单位技术合作,首次采用泡生法生长了不同浓度的115kg级钛宝石晶体,掺杂浓度(质量分数)分别为0.1%㊁0.15%㊁0.25%和0.5%,并对生长晶体的闪烁发光性能进行了分析㊂1㊀实㊀㊀验通过自主设计制造的泡生法长晶炉,设计了侧壁主加热和底部辅助加热的多温区石墨热场结构㊂晶体生长配料质量为115kg,按照浓度配比称量TiO2粉末混入2kg高纯Al2O3粉末,混合均匀后压制成粉饼,按生长浓度将粉饼和Al2O3火焰法结晶料混合装入钨坩埚中,依次经过升温化料㊁引晶㊁放肩㊁等径生长㊁降温退火的工艺流程,在Ar+CO+CO2混合流动气氛环境中进行钛宝石长晶㊂化料主加热功率约40kW,生长全周期约43~45d,长晶结束后晶体原位进行退火处理,退火时间约6d㊂生长的钛宝石晶体外形完整未开裂,呈现暗红色,部分晶体照片如图1所示,晶体尺寸:上部直径290~ 305mm,下部直径360~400mm,高度340~380mm㊂图1㊀泡生法生长的部分钛宝石晶体Fig.1㊀Partial TiʒAl2O3crystals grown by Kyropoulos method经检测,微气泡和包裹体是泡生法生长钛宝石晶体中的主要缺陷种类㊂微气泡主要来源于Ti离子掺杂及其偏析以及氧化铝原料的分解;包裹体主要来源于生长环境引入的杂质,如:钨坩埚析出的金属杂质㊁石墨热场挥发产生的C杂质等㊂微气泡的存在会严重降低晶体的透过率从而影响其光学性能[19-21]㊂764㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第50卷通过定向切割加工,生长钛宝石晶体已经能够制备出高品质的大尺寸钛宝石样品,可用于强激光装置和电磁量能器装置,如图2所示㊂图2㊀加工的部分钛宝石晶体样品Fig.2㊀Processed TiʒAl 2O 3crystal2㊀结果与讨论在生长晶体的中间部位沿A 面进行定向切割,加工成尺寸为10mm ˑ10mm ˑ10mm 的方块样品,如图3所示㊂室温下测试了可见光波段不同浓度钛宝石的吸收曲线,结果如图4所示,0.1%㊁0.15%㊁0.25%㊁0.5%(质量分数)TiʒAl 2O 3晶体在400~650nm 波段有宽带吸收,中心波长位于490nm,计算其吸收系数分别为:0.07cm -1㊁0.25cm -1㊁0.40cm -1和1.10cm -1㊂钛宝石晶体闪烁性能的测试是在加州理工学院(California Institute of Technology)朱人元教授课题组进行的,选择低浓度0.1%和高浓度0.5%晶体加工成10mm ˑ10mm ˑ4mm 片状样品,分别标记Al 2O 3ʒTi-1和Al 2O 3ʒTi-2,分别在X 射线和241Amα粒子激发下测试了两样品的发射谱和发光衰减时间,结果如图5~7所示㊂图3㊀经定向切割加工的TiʒAl 2O 3晶体方块样品Fig.3㊀TiʒAl 2O 3crystal cubic samples processed by directionalcutting 图4㊀不同浓度钛宝石晶体的吸收谱Fig.4㊀Absorption spectra of TiʒAl 2O 3crystals with differentconcentrations 图5㊀X 射线激发下Al 2O 3ʒTi-1和Al 2O 3ʒTi-2的发射光谱Fig.5㊀Emission spectra of Al 2O 3ʒTi-1and Al 2O 3ʒTi-2excited with X-ray㊀第4期王庆国等:钛宝石晶体的泡生法生长和闪烁发光性能765㊀图5显示了X 射线激发下Al 2O 3ʒTi-1(0.1%)和Al 2O 3ʒTi-2(0.5%)样品的发射光谱,其发射光谱主要包括紫外发光带(280~350nm)和近红外发光带(600~900nm)㊂其中紫外发光带位于280~350nm 范围,该发光来源于F +心发射或Ti 局域激子[8],当掺杂浓度较高时,该发射波段有较强的自吸收㊂近红外发射带来自Ti 3+的3d1电子组态的2E ң2T 2跃迁发射[8],该发射有较高的发光效率和低的自吸收㊂本文中的样品紫外发射的占比比文献[5]报道的要低,可能是由于所用探测器光谱响应的差异,也可能是来自不同发光中心浓度的差异㊂图6和图7分别显示了不同时间尺度下的光输出随时间的增长和发光衰减时间,它们分别显示出了样品的快㊁慢时间成分㊂经过曲线拟合可以获得低浓度(0.1%)的Al 2O 3ʒTi-1样品的快㊁慢时间成分分别为151ns 和3195ns,高浓度(0.5%)的Al 2O 3ʒTi-2样品的快慢时间成分分别为175ns 和3174ns㊂其中快成分主要来自紫外发射,而慢成分来自于Ti 3+的特征发射㊂图6㊀241Amα粒子激发下Al 2O 3ʒTi-1和Al 2O 3ʒTi-2的光输出随时间的变化Fig.6㊀Relationship between optical output and time of Al 2O 3ʒTi-1and Al 2O 3ʒTi-2excited by 241Amαparticles 图7㊀241Amα粒子激发下Al 2O 3ʒTi-1和Al 2O 3ʒTi-2的发光衰减时间Fig.7㊀Luminescence decay time of Al 2O 3ʒTi-1and Al 2O 3ʒTi-2excited by 241Amαparticles图8是241Amα粒子激发下Al 2O 3ʒTi-1(0.1%)和Al 2O 3ʒTi-2(0.5%)样品的脉冲幅度谱,采用时间门为6μs,获得的光产额分别为955.6pe /MeV 和1130.5pe /MeV㊂由于采用了较慢的时间门,幅度谱计数中包含了快成分和慢成分,Al 2O 3ʒTi-2样品的全能峰道数略高于Al 2O 3ʒTi-1样品,表明Al 2O 3ʒTi-2样品具有略高的光输出,这与图5中总光谱积分强度较为一致㊂图9显示了α粒子激发下Al 2O 3ʒTi-1(0.1%)和Al 2O 3ʒTi-2(0.5%)样品快成分的脉冲幅度谱,采用时间门为200ns,该时间范围收集的主要是快成分发光㊂Al 2O 3ʒTi-1和Al 2O 3ʒTi-2样品的光产额分别是8.8pe /MeV 和29.6pe /MeV,表明Al 2O 3ʒTi-2样品的快成分光输出是Al 2O 3ʒTi-1样品的3.4倍,与图5中的X 射线激发下紫外发射光谱积分强度比值基本一致㊂对它们的全能峰拟合可以获得能量分辨率分别为43.7%和26.7%㊂通过光谱测试结果表明:钛宝石(TiʒAl 2O 3)的闪烁发光主要包含了近红外和近紫外发光㊂近红外发光的来源较为明确,属于Ti 3+的特征发射,其特点是发光效率高㊁自吸收弱,但衰减时间较慢,对于不追求时间分辨的应用场合,该发光可以被很好的利用㊂近紫外发光的来源较为复杂,包括了Ti 局域激子发光和F +心发光,其衰减时间较快(约为150ns 附近),当Ti 掺杂浓度较高时其自吸收较强烈导致光输出降低㊂此外,作为电磁量能器大装置用闪烁体材料,晶体用量很大(~m 3级),相比于其他闪烁晶体如:LYSO㊁BaF 2㊁BGO 等,钛宝石具有更低的长晶加工成本,且可以生长大尺寸(口径>200mm)的体块晶体,是其他闪烁晶体所无法比拟的优势㊂766㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第50卷图8㊀241Amα粒子激发下Al2O3ʒTi-1和Al2O3ʒTi-2的脉冲幅度谱Fig.8㊀Pulse amplitude spectra of Al2O3ʒTi-1andAl2O3ʒTi-2excited by241Amαparticles图9㊀241Amα粒子激发下Al2O3ʒTi-1和Al2O3ʒTi-2快成分的脉冲幅度谱Fig.9㊀Pulse amplitude spectra of fast components in Al2O3ʒTi-1and Al2O3ʒTi-2excited by241Amαparticles3㊀结㊀㊀论采用泡生法生长了115kg级大尺寸钛宝石(TiʒAl2O3)晶体,闪烁发光测试表明TiʒAl2O3晶体包含近红外和近紫外闪烁发光㊂近红外发光来源于Ti3+特征发射,效率较高,衰减时间慢㊂近紫外发光来源于Ti局域激子发光和F+心发光,具有较快的衰减时间㊂α粒子激发下,光产额可以达到1130.5pe/MeV,其中快成分发光产额可以达到29.6pe/MeV㊂对于具有快衰减时间分辨的应用场合,需要尽可能提高近紫外发光产额㊂由于近紫外发光与掺杂和缺陷相关,需要进一步优化掺杂和缺陷调控的工艺以获得快闪烁发光成分的优化㊂参考文献[1]㊀MOULTON P F.Spectroscopic and laser characteristics of TiʒAl2O3[J].Josa B,1986,3(1):125-133.[2]㊀张小翠,司继良,徐㊀民,等.钛宝石晶体的制备㊁光学和激光性能研究[J].中国激光,2014,41(5):157-161.ZHANG X C,SI J L,XU M,et al.Growth method,optical and laser properties of titanium-doped sapphire crystals[J].Chinese Journal of Lasers,2014,41(5):157-161(in Chinese).[3]㊀BUSSIÈRE B,UTÉZA O,SANNER N,et al.Bulk laser-induced damage threshold of titanium-doped sapphire crystals[J].Applied Optics,2012,51(32):7826-7833.[4]㊀ANGLOHER G,BRUCKMAYER M,BUCCI C,et al.Limits on WIMP dark matter using sapphire cryogenic detectors[J].AstroparticlePhysics,2002,18(1):43-55.[5]㊀LUCA M,CORON N,DUJARDIN C,et al.Scintillating and optical spectroscopy of Al2O3ʒTi for dark matter searches[J].Nuclear Instrumentsand Methods in Physics Research A:Accelerators,Spectrometers,Detectors and Associated Equipment,2009,606(3):545-551. [6]㊀MIKHAILIK V B,KRAUS H,BALCERZYK M,et al.Low-temperature spectroscopic and scintillation characterisation of Ti-doped Al2O3[J].Nuclear Instruments and Methods in Physics Research Section A:Accelerators,Spectrometers,Detectors and Associated Equipment,2005,546(3):523-534.[7]㊀GALUNOV N Z,GORBACHEVA T E,GRINYOV B V,et al.Radiation resistant composite scintillators based on Al2O3ʒTi grains and theirproperties after irradiation[J].Nuclear Instruments and Methods in Physics Research Section A:Accelerators,Spectrometers,Detectors and Associated Equipment,2017,866:104-110.[8]㊀MIKHAILIK V B,KRAUS H,WAHL D,et al.Luminescence studies of Ti-doped Al2O3using vacuum ultraviolet synchrotron radiation[J].Applied Physics Letters,2005,86(10):101909.[9]㊀LACOVARA P,ESTEROWITZ L,KOKTA M.Growth,spectroscopy,and lasing of titanium-doped sapphire[J].IEEE Journal of QuantumElectronics,1985,21(10):1614-1618.[10]㊀UECKER R,KLIMM D,GANSCHOW S,et al.Czochralski growth of Tiʒsapphire laser crystals[C]//European Symposium on Optics andPhotonics for Defence and Security.Proc SPIE5990,Optically Based Materials and Optically Based Biological and Chemical Sensing for Defence II,Bruges,Belgium.2005,5990:599006.[11]㊀JOYCE D B,SCHMID F.Progress in the growth of large scale Tiʒsapphire crystals by the heat exchanger method(HEM)for petawatt class lasers㊀第4期王庆国等:钛宝石晶体的泡生法生长和闪烁发光性能767㊀[J].Journal of Crystal Growth,2010,312(8):1138-1141.[12]㊀NING K J,LIU Y C,MA J,et al.Growth and characterization of large-scale Tiʒsapphire crystal using heat exchange method for ultra-fast ultra-high-power lasers[J].CrystEngComm,2015,17(14):2801-2805.[13]㊀DONG J,DENG P Z.Tiʒsapphire crystal used in ultrafast lasers and amplifiers[J].Journal of Crystal Growth,2004,261(4):514-519.[14]㊀NIZHANKOVSKIY S V,DAN KO A Y,KRIVONOSOV E V,et al.Growth of large Tiʒsapphire crystals by horizontal directional solidification inargon atmosphere[J].Inorganic Materials,2010,46(1):35-37.[15]㊀NEHARI A,BRENIER A,PANZER G,et al.Ti-doped sapphire(Al2O3)single crystals grown by the Kyropoulos technique and opticalcharacterizations[J].Crystal Growth&Design,2011,11(2):445-448.[16]㊀ALOMBERT-GOGET G,SEN G,PEZZANI C,et rge Ti-doped sapphire single crystals grown by the Kyropoulos technique for petawattpower laser application[J].Optical Materials,2016,61:21-24.[17]㊀ALOMBERT-GOGET G,GUYOT Y,NEHARI A,et al.Scattering defect in large diameter titanium-doped sapphire crystals grown by theKyropoulos technique[J].CrystEngComm,2018,20(4):412-419.[18]㊀STELIAN C,ALOMBERT-GOGET G,SEN G,et al.Interface effect on titanium distribution during Ti-doped sapphire crystals grown by theKyropoulos method[J].Optical Materials,2017,69:73-80.[19]㊀GHEZAL E A,LI H,NEHARI A,et al.Effect of pulling rate on bubbles distribution in sapphire crystals grown by the micropulling down(μ-PD)technique[J].Crystal Growth&Design,2012,12(8):4098-4103.[20]㊀LI H,GHEZAL E A,ALOMBERT-GOGET G,et al.Qualitative and quantitative bubbles defects analysis in undoped and Ti-doped sapphirecrystals grown by Czochralski technique[J].Optical Materials,2014,37:132-138.[21]㊀LI H,GHEZAL E A,NEHARI A,et al.Bubbles defects distribution in sapphire bulk crystals grown by Czochralski technique[J].OpticalMaterials,2013,35(5):1071-1076.。
石墨烯“表亲”硅烯晶体管首秀
当前文档由后花园网文自动生成，更多内容请访问 石墨烯“表亲”硅烯晶体管首秀来源于:环球科学2月初，研究者揭示了第一块硅烯晶体管的相关细节，如果这种硅薄层结构能应用于电子设备的制造，可能会推动半导体工业实现终极的微型化。
七年前，硅烯还只是理论家的一个梦。
在对石墨烯（单原子层厚度、蜂巢状的碳材料）的狂热兴趣的驱动下，研究者推测硅原子也许也能形成类似的层状结构。
而如果这种硅薄层结构能应用于电子设备的制造，可能会推动半导体工业实现终极的微型化。
2月初，研究者揭示了第一块硅烯晶体管的相关细节，向实现梦想的方向迈出了关键一步。
参与晶体管制作的德州大学奥斯汀分校（University of Texas at Austin）纳米材料学家德吉?阿金万德（Deji Akinwande）说，虽然设备表现平庸，且寿命只有几分钟，但硅烯这一概念的验证已足以让与会人员精神大振。
法国艾克斯?马赛大学（Aix-Marseille University）的材料学家居伊?勒莱（Guy Le Lay）对此表示赞同。
“没人会预料到，他们能在这么短的一段时间内，用尚未存在的材料做出晶体管。
”他说。
勒莱是2012年首先在实验室条件下制备出硅烯的科学家之一。
硅烯晶体管首次诞生的这段时间，刚好也是科学家渐渐意识到石墨烯无法适用于晶体管的时候。
石墨烯也许是世界上导电性最强的物质，但在一个重要的特性上，有别于计算机芯片中常用的半导体材料，石墨烯没有带隙（band gap）。
带隙是电子在携带电流前必须跨过的能级障碍，它使半导体材料可具有“开”、“关”两种状态，从而可用于二进制逻辑操作。
硅烯的崛起一直以来，都是硅烯的碳基“表亲”石墨烯吸引着更多注意，但硅烯正迎头赶上。
1994 首次计算出硅和锗的二维晶体结构（硅结构如上图）2004 安德烈?海姆（Andre Geim）和康斯坦丁?诺沃肖洛夫（Konstantin Novoselov）完成石墨烯的分离2007 创造术语“硅烯”2009 硅烯纳米带的制造；硅烯和锗烯理论方面的文章进入爆发期2010 海姆和诺沃肖洛夫因其在石墨烯方面的重要实验获得诺贝尔物理学奖2012六篇独立研究报道了在银表面制备出的硅烯层2015 首次硅烯晶体管展示“就逻辑电路方面的应用而言，石墨烯没什么希望。
InAsGaSb超晶格及量子点材料生长研究的开题报告
InAsGaSb超晶格及量子点材料生长研究的开题报告一、课题研究的背景和意义红外光电探测技术是现代科技领域中的热门研究方向之一，其在军事、航天、医疗等领域具有广泛的应用前景。
而在红外探测器中，InAsGaSb超晶格及量子点材料因其在红外波段中的优异特性而备受关注。
然而，InAsGaSb超晶格及量子点材料的制备技术尚不十分成熟，研究仍处于基础阶段，面临着诸多挑战和困难。
因此，开展InAsGaSb超晶格及量子点材料的生长研究，对于推动红外光电探测技术的发展具有重要的意义和价值。
二、研究目标和内容本课题旨在探究InAsGaSb超晶格及量子点材料的生长机制和优化方法，实现高品质的材料制备，并对其进行结构、光学等性质的表征。
具体的研究内容包括以下几个方面：1.基于分子束外延技术，在InAs和GaSb衬底上生长InAsGaSb超晶格结构及其探索过程控制和优化方法。
2.通过有效的控制材料的生长条件，调节其生长速率和厚度，提高InAsGaSb超晶格结构中的材料质量和适用性。
3.在制备过程中加入掺杂剂，探究掺杂对InAsGaSb超晶格结构中电学性质和光学性质的影响。
4.通过先进的表征手段，包括X射线衍射、光电流谱、扫描透射电镜等，对InAsGaSb超晶格结构中的材料性质进行详细的表征。
三、研究方法本研究将采用分子束外延技术，通过有效的生长条件控制和优化方法，制备高品质的InAsGaSb超晶格结构材料。
同时，通过掺杂剂在制备过程中的加入以及先进的表征手段的应用，对材料的结构、电学性质和光学性质等进行详细的分析。
四、预期研究结果通过本次研究，期望实现高质量、优异性能的InAsGaSb超晶格及量子点材料的制备，在红外光电探测器等领域中发挥重要的应用价值。
同时，也将对相关研究提供重要的实验基础和参考数据。
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Journal of Crystal Growth 240(2002)185–189Crystal growth and morphology of substituted gadoliniumgallium garnetYiting Fei a,b,*,Mitch M.C.Chou b ,BruceH .T.Chai a,baCREOL,University of Central Florida,Orlando,FL 32816,USA bCrystal Photonics,Inc.,5525Benchmark Lane,Sanford,FL 32773,USAReceived 25September 2001;accepted 17January 2002Communicated by R.S.FeigelsonAbstractSubstituted gadolinium gallium garnet (SGGG)crystals with calcium,magnesium and zirconium as substituting ions have been used as substrates for bismuth-substituted iron garnet epitaxial films.Single crystals have been grown from theme lt composition Gd 2.68Ca 0.32Ga 4.04Mg 0.32Zr 0.64O 12using the Czochralski pulling technique.Spiral growth is the most common problem in this system.With proper adjustment of the growth environment,colorless and optically transparent single crystals of SGGG up to 2in diameter and 125mm in length were produced.We will discuss the effect of different growth parameters on the crystal morphology,and propose an optimum growth condition for SGGG crystals.r 2002Elsevier Science B.V.All rights reserved.PACS:81.10.Fq;81.90.+c;75.50.GgKeywords:A1.Morphology;A2.Czochralski method;B1.Substituted gadolinium gallium garnet1.IntroductionBismuth-substituted iron garnet epitaxial films grown by the liquid phase epitaxy (LPE)method on rare earth gallium garnet substrates can be used as magneto-optical devices such as optical iso-lators or data storageme dia.Themagnitudeof the Faraday rotation depends linearly on the Bi 3+concentration in the garnet epilayers,and the lattice parameter of the garnet increases linearly with increasing Bi 3+concentration [1].Gadoli-nium gallium garnet Gd 3Ga 5O 12(GGG)is oneof the most extensively developed garnet material for substrate,but its lattice parameter (1.238nm)is just too small to beuse d as substratefor high bismuth-substituted iron garnet epilayers [2].The method to increase the lattice parameters of GGG singlecrystals is thecouple d substitution of gallium by magnesium and zirconium,and gadolinium by calcium [3].As a result,single crystal with thecomposition Gd 3Àx Ca x Ga 5Àx À2y -Mg y Zr x+y O 12(SGGG)and lattice parameters within therangefrom 1.2453to 1.2507nm can begrown from a me lt composition in which 0.31p x p 0.45,0p y p 0.37and 0.45p x þy p 0.68.The final lattice parameters as well as the*Corresponding author.5525Benchmark Lane,Sanford,FL 32773,USA.Tel.:+1-407-328-9111;fax:+1-407-328-9799.E-mail address:ytfei@ (Y.Fei).0022-0248/02/$-see front matter r 2002Elsevier Science B.V.All rights reserved.PII:S 0022-0248(02)00876-Xdistribution coefficients are controlled by the concentrations of the substituting ions.Similar to thegrowth of many gallium-garne ts, SGGG crystals also show a strong tendency of spiral or acentric growth habit.In this paper,we describe our effort to achieve the successful growth of2in diameter SGGG single crystals.We will discuss the crystal morphology under different growth conditions.2.Crystal growthThestarting mate rials(Gd2O3,Ga2O3,CaO, MgO and ZrO2powders with at least99.99% purity)were mixed mechanically according to the stoichiometric molar ratio.In order to compensate theloss of e vaporation of gallium oxideduring growth,3mol%excess of Ga2O3is added into the starting charge.The crystal growth experiments were carried out in an automatic diameter-controlled Czochralski (CZ)crystal-pulling furnacedrive n by a50kW RF generator.About20%starting materials powder wasfirst loaded in an iridium crucible with80mm in both diameter and height,and heated to melting.The rest of the charge was then hot-loaded in the crucible and allowed to charge melt. In order to stabilize the crystal growth,we usually put an iridium ring lid on top of thecrucible.The crystals were grown at a rate of1.0–1.5mm/h and rotated at4–8rpm under nitrogen atmosphere.All these single crystals were grown in[111]direction using seed crystals of either GGG or SGGG. Under the above mentioned growth condition, wewe reableto produceSGGG singlecrystals of 2in diameter and130mm length with melt composition of Gd2.68Ca0.32Ga4.04Mg0.32Zr0.64O12.3.Results and discussionpositionIt was reported that single crystals of the composition Gd3Àx Ca x Ga5ÀxÀ2y Mg y Zr x+y O12with latticeparame te rs within therangefrom1.2453to 1.2507nm can begrown from me lt composition in which0.31p x p0.45,0p y p0.37and0.45p xþy p0.68[3].Table1shows thecrystal compo-sitions and their respective lattice parameters[3,4]. In our present research work,we have grown the SGGG singlecrystals with thecom-position Gd2.68Ca0.32Ga4.04Mg0.32Zr0.64O12and a latticeconstant of1.2498nm.The garnet structure can be expressed as C3A2D3O12,where C,A,D represent different cation sites.The unit cell of the cubic system garnet structure contains eight units of C3A2D3O12,with cations occupying thedode cahe-dral(C-site),octahedral(A-site),and tetrahedral (D-site)sites,respectively[5].For example,the formula of GGG should be expressed as Gd3Ga2-Ga3O12.To increase the lattice constant of GGG crystals,theGd3+ion(0.106nm)in thedode cahe-dral siteis partially substitute d by Ca2+with a larger ionic radius of0.112nm,and the Ga3+ion (0.062nm)in theoctahe dral siteis also partially substituted by cations with larger ionic radii such as Mg2+(0.072nm)and Zr4+(0.075nm).There-fore,the SGGG crystal will have the composition of(Gd2.68Ca0.32)(Ga1.04Mg0.32Zr0.64)Ga3O12and a latticeconstant of 1.2498nm,which matche s with that of bismuth-substituted iron garnet epitaxial layers.3.2.Growth parameters and morphologyUnder the normal growth condition,all the SGGG single crystals grown by CZ method were spiral and twisted.This kind of acentric growth was observed in many other gallium garnet crystals.Fig.1shows theSGGG crystal with 40mm diameter grown by CZ method from the beginning(No.1),which has a strong spiral growth from theconeto thebottom.Table1Crystal compositions and their lattice parameters Composition a0(nm) Gd2.60Ca0.40Ga4.1Mg0.25Zr0.65O12 1.249 Gd2.65Ca0.35Ga4.35Mg0.15Zr0.50O12 1.247 Gd2.65Ca0.35Ga4.05Mg0.30Zr0.65O12 1.250 Gd2.68Ca0.32Ga4.04Mg0.32Zr0.64O12 1.2498Y.Fei et al./Journal of Crystal Growth240(2002)185–189 186There are several possible explanations for the spiral or twisted growth of SGGG crystal [3,6].(1)Surface tension .Spiral growth might arisefrom large surface tension,so decrease of surface tension is helpful to prevent spiral or twisted growth.It has been measured that Ca 2+and Mg 2+can decrease,but Zr 4+will increase the surface tension.For substituted gadolinium gallium garnet crystal,the doped Ca and Mg ions seem to have little effect in minimizing thespiral growth,appare ntly the Zr ions has a much stronger effect because they were counteracted by the doped Zr ions.(2)Temperature gradient .It was a generallyaccepted fact that a small temperature gra-dient at the growth interface would result in spiral growth.Therefore,increasing tempera-ture gradient should reduce spiral or twisted growth.(3)Heat conductivity and viscosity .A possiblevariation of thehe at conductivity in the crystal as well as that of the viscosity in the melt has an effect on the spiral growth.However,the detailed mechanism is still not well defined.In order to increase the temperature gradients at the growth interface,we modified our CZ techni-queby raising thecrucible1–2in highe r than the normal position relative to the RF coil.As shownin Fig.2,colorless and optically transparent single crystals of SGGG (No.2)with 40mm diameter were grown.However,the growth length is limited to 50mm.After that,the crystal grows by a foot and the diameter control is totally lost.From these results,we can observe that raising the crucible can improvethegrowth of SGGG,but cannot solve the spiral growth problem completely.In theproce ss of solving thespiral growth problem,we noticed that the crucible’s position has a tremendous effect on the growth stability of SGGG crystals.So webe gan by adjusting the cruciblepositions.To our surprise ,weobtaine d better growth results by lowering the crucible 2–3in within theRF coil,as shown in Fig.3.The SGGG crystal produced has 42mm diameter (No.3)and is optically transparent.A couple of small cracks appear around the seed and the cone region,but they do not extend down to the whole crystal.After the growth length reached about 100mm,thecrystal also starte d to form a foot and the growth had to be terminated.The total raw materials usage was only 55%.Thene xt modification was to usethesameRF coil but a longer quartz tube.We were able to grow the colorless and optically transparent SGGG single crystal (No.4)with 2in diameter and totally cylindrical shape,as shown in Fig.4.Fig.1.SGGG spiral crystal (No.1)with 40mm diameter grown by CZmethod.Fig.2.SGGG crystal (No.2)with 40mm diameter by raising thecrucibleposition.Y.Fei et al./Journal of Crystal Growth 240(2002)185–189187Again,no crack was found insidethecrystal with full diameter except some of them around the cone.Although the vertical temperature gradient becomes smaller by lowering the crucible,the gradient difference between the radial and vertical direction is larger as compared while raising the crucible.This leads to a different intensity of natural convection and melt flow during crystal growth.From our experimental results,a larger temperature gradient difference between the radial and vertical direction seems to have a more positive effect in preventing the spiral growth of SGGG crystal.In thegrowth runs from No.1–4,weuseGGG crystal as seed with /111S direction.However,some cracks always appeared around the seed and coneare a.This is primarily dueto themismatch of the lattice parameters between GGG (a 0¼1:238nm)and SGGG (a 0¼1:250nm).Therefore,when we used the SGGG seed with the same /111S orientation,the quality of SGGG crystal (No.5)as shown in Fig.5is much improved.This crystal with 2in diameter and 125mm length is crack-free and optically transparent.The usage of the raw materials also increases to about 80%.Thegrowth conditions of all theSGGG crystals aresummarize d in Table2.4.ConclusionSubstituted gadolinium gallium garnet (SGGG)crystals with calcium,magnesium and zirconium as substituting ions,which areuse d as the substrates for the growth of bismuth-substituted iron garnet epitaxial layers,have been grown from theme lt composition Gd 2.68Ca 0.32Ga 4.04Mg 0.32-Zr 0.64O 12by using Czochralski pulling technique.Although thespiral growth was themost se rious problem for SGGG,we were able to grow crack-free and optically transparent single crystals of SGGG up to 2in diameter and 125mm in length using only 80mm diameter crucibles with more than 80%yield.We found that lowering the crucibleposition within theRF coil produce s better results without spiral growth.Changing the crucible position creates a largertemperatureFig.3.SGGG crystal (No.3)with 42mm diameter by loweringthecrucibleposition.Fig.4.SGGG crystal (No.4)grown in a longer heating zonewith 2in diameter by lowering the crucibleposition.Fig.5.SGGG crystal (No.5)with 2in diameter using SGGG as the seed.Y.Fei et al./Journal of Crystal Growth 240(2002)185–189188gradient difference between the radial and vertical direction,which has a more positive effect in preventing the spiral growth of SGGG crystals. Using SGGG seed with/111S direction,we are able to grow crack-free single crystals.The result is clearly better than GGG seed that has a lattice mismatch problem.The growth condition for these high-quality SGGG crystals aregrowth rateat 1.0–1.5mm/h and rotation rateat4–8rpm unde r pure nitrogen atmosphere and lower crucible position.References[1]K.Shimamura,V.V.Kochurikhin,H.Takeda,T.Fukuda,J.Crystal Growth194(1998)203.[2]J.R.Carruthers,M.Kokta,R.L.Barns,M.Grasso,J.Crystal Growth19(1973)204.[3]D.Mateika,urien,Ch.Rusche,J.Crystal Growth56(1982)677.[4]V.J.Fratello,H.M.O’Bryan, C.D.Brandle,J.CrystalGrowth166(1996)774.[5]G.Geller,Z.Kristallogr.125(1967)1.[6]M.Kumatoriya,T.Fukuda,J.Jpn.Assoc.Crystal Growth21(1994)144(in Japanese).Table2SGGG crystal growth parameters and propertiesNo.12345Position Normal Higher Lower Lower LowerSeed GGG GGG GGG GGG SGGGPulling(mm/h) 1.5 1.5 1.2 1.2 1.0Rotation(rpm)58544Diameter(mm)404042200200Length(mm)6550100130125Utility ratio(%)2817558080Quality Spiral Twisted Cylinder,crack Cylinder,crack Cylinder,crack-freeY.Fei et al./Journal of Crystal Growth240(2002)185–189189。