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Effect of valence electron concentration on stability of fcc or bcc phase in high entropy alloys

See discussions, stats, and author profiles for this publication at: /publication/229595062 Effect of valence electron concentration on stability of fcc or bcc phase in high entropy alloysARTICLE in JOURNAL OF APPLIED PHYSICS · MAY 2011Impact Factor: 2.19 · DOI: 10.1063/1.3587228CITATIONS 80DOWNLOADS143VIEWS4104 AUTHORS, INCLUDING:Sheng GuoChalmers University of Technology29 PUBLICATIONS 329 CITATIONSSEE PROFILEAvailable from: Sheng GuoRetrieved on: 16 September 2015Effect of valence electron concentration on stability of fcc or bcc phase in high entropy alloysSheng Guo,1Chun Ng,1Jian Lu,2and C.T.Liu1,a)1Department of Mechanical Engineering,The Hong Kong Polytechnic University,Hung Hom,Kowloon,Hong Kong,People’s Republic of China2College of Science and Engineering,City University of Hong Kong,Kowloon,Hong Kong(Received8March2011;accepted3April2011;published online16May2011)Phase stability is an important topic for high entropy alloys(HEAs),but the understanding to it isvery limited.The capability to predict phase stability from fundamental properties of constituentelements would beneﬁt the alloy design greatly.The relationship between phase stability andphysicochemical/thermodynamic properties of alloying components in HEAs was studiedsystematically.The mixing enthalpy is found to be the key factor controlling the formation of solidsolutions or compounds.The stability of fcc and bcc solid solutions is well delineated by thevalance electron concentration(VEC).The revealing of the effect of the VEC on the phase stabilityis vitally important for alloy design and for controlling the mechanical behavior of HEAs.V C2011American Institute of Physics.[doi:10.1063/1.3587228]I.INTRODUCTIONHigh entropy alloys(HEAs)constitute a new type of metallic alloys for structural and particularly high-tempera-ture applications,due to their high hardness,wear resistance, high-temperature softening resistance and oxidation resist-ance.1–3HEAs are typically composed of more thanﬁve me-tallic elements in equal or near-equal atomic ratios,and interestingly they tend to form solid solution structure (mainly fcc and/or bcc)rather than multiple intermetallic compounds as expected from general physical metallurgy principles.They were termed as HEAs because the entropy of mixing is high when the alloying elements are in equia-tomic ratio,and it was initially believed that the high entropy of mixing leads to the formation of the solid solution struc-ture rather than intermetallic compounds.The generally used alloying elements in HEAs are fcc-type Cu,Al,Ni,bcc-type Fe,Cr,Mo,V and hcp-type Ti,Co (crystal structure at ambient temperature).When these alloy-ing elements are mixed with different combination,or with same combination but different amount of certain elements, fcc,bcc or mixed fcc and bcc structures may form.For example,cast CoCrCuFeNi(in atomic ratio,same after-wards)has the fcc structure while AlCoCrCuFeNi has the fccþbcc structure;4and the amount of Al in the Al x CoCrCu-FeNi system can tune the crystal structure from fcc to fccþbcc and to fully bcc4.The structure directly affects the mechanical properties,and to take again the Al x CoCrCuFeNi system as an example:with increasing x,the structure changes from fcc to fccþbcc andﬁnally to bcc;the hardness and strength increase with the increasing amount of bcc phases but the alloys get brittle.4,5Although the embrittle-ment mechanism by bcc phases still needs further explora-tion,it is certainly important to be able to control the formation of bcc phases.The target of this work is hence to ﬁnd out the physical parameters that control the stability for the fcc and bcc phases in HEAs.II.ANALYSISWang et al.brieﬂy discussed the reason of addition of Al in the Al x CoCrCu1Àx FeNiTi0.5system causing the struc-tural transition from fcc to bcc.6They claimed that the alloy-ing of larger Al atoms introduces the lattice distortion energy,and the formation of a lower atomic-packing-efﬁ-ciency structure,such as bcc,can decrease this distortion energy.This does make sense but is far away from being sat-isfactory;besides,it can not quantitatively predict when the bcc structure will form as a function of Al additions.Ke et al.claimed that,in the Al x Co y Cr z Cu0.5Fe v Ni w system,Ni and Co are fcc stabilizers and Al and Cr are bcc stablizers;1.11Co is equivalent to Ni as the fcc stablizers and2.23Cr is equivalent to Al for the bcc stablizers.Furthermore,if the equivalent Co%is greater than45at.%,the alloy has an fcc structure,and the alloy has a bcc structure if the equivalent Cr%is greater than55at.%.7This empirical rule is useful but it has no scientiﬁc merits and is valid only for the speciﬁc alloy systems.The establishment of scientiﬁc principles to control the crystal structures in HEAs can also contribute to the alloy design of HEAs with desirable properties.For example,we can use less expensive Ni to partially or com-pletely replace more expensive Co;or we can reduce the amount of Cu which is known to cause segregation issue because the mainly positive enthalpy of mixing between Cu and other alloying elements.4As a test to the equivalency of Ni and Co as fcc stabil-izers,we prepared a series of Al x CrCuFeNi2(0.2x 1.2) alloys to study the effect of Al amount on the phase stability in this alloy system,in comparison to the well studied Al x CoCrCuFeNi system.The alloys were prepared by arc-melting a mixture of the constituent elements with purity better than99.9%in a Ti-gettered high-purity argon atmos-phere.Repeated melting was carried out at leastﬁve times toa)Author to whom correspondence should be addressed.Electronic mail:mmct8tc@.hk.0021-8979/2011/109(10)/103505/5/$30.00V C2011American Institute of Physics109,103505-1JOURNAL OF APPLIED PHYSICS109,103505(2011)improve the chemical homogeneity of the alloy.The molten alloy was drop-cast into a10mm diameter copper mold.The phase constitution of the alloy was examined by X-ray dif-fractometer using Co radiation(Bruker AXS D8Discover). The X-ray diffraction patterns are shown in Fig.1where it is clear that at x0.8,the alloys have a single fcc structure and the bcc phase starts to appear at x¼1.0.In the Al x CoCrCu-FeNi system,fully fcc structure is obtained at x0.5and bcc phase starts to appear at x>0.8.4The experimental results indicate that Co is not necessarily required in obtain-ing the solid solution structure in HEAs,which is good foralloy design from economy concerns.This new alloy systemalso provides more data to study the phase stability in HEAs,ideally from the consideration of the fundamental propertiesof constituent alloying elements.Zhang et al.studied the relationship between the phasestability and the atomic size difference,d(¼100ﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃP Ni¼1c ið1Àr i=rÞ2q,r¼P ni¼1c i r i,where c i and r i areatomic percentage and atomic radius of the i th component),and also the mixing enthalpy,D H mix(¼P ni¼1;i¼jX ij c i c j,X ij¼4D AB mix,where D AB mix is the mixing enthalpy of binaryliquid AB alloys)for multi-component alloys.8They foundthat the solid solution tends to form in the region delineatedbyÀ15KJ/mol D H mix5KJ/mol and1d 6.Therequirement of atomic size difference for formation of thesolid solution structure is not surprising as basically it is inline with the well established Hume-Rothery rule.9Othertwo requirements from the Hume-Rothery rule to form thesolid solution are electronegativity and electron concentra-tion.Fang et al.deﬁned the electronegativity difference in amulti-component alloy system as D v(¼ﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃP ni¼1c iðv iÀvÞ2q,v¼P ni¼1c i v i,where v i is the Pauling electronegativity forthe i th component).10The effect of electron concentration isa little bit more complex.There are basically two deﬁnitionsof the electron concentration:average number of itinerantelectrons per atom,e/a,and the number of total electronsincluding the d-electrons accommodated in the valenceband,valence electron concentration or VEC.11,12e/a orVEC for a multi-component alloy can be deﬁned as theweighted average from e/a or VEC of the constituent compo-nents:e/a¼P ni¼1c iðe=aÞi or VEC¼P ni¼1c iðVECÞi,where(e/a)i and(VEC)i are the e/a and VEC for the individual ele-ment.Hume-Rothery rule works with the e/a deﬁnition ande/a has clear effect on the crystal structure for the so-calledelectron compounds or Hume-Rothery compounds.9How-ever,the HEAs comprise mainly transition metals(TMs)ande/a for TMs are very controversial.11Very recently,Mizutanireviewed the various deﬁnitions of e/a for TMs and con-cluded that e/a for TMs are small positive numbers.11Unfortunately,not all e/a for TMs have been determined ande/a for a TM element even varies in different environment.For convenience,VEC was used here to study the electronconcentration effect on the phase stability in HEAs.III.RESULTSFollowing Zhang et al.’s method,8the atomic size dif-ference,d,and the mixing enthalpy,D H mix for the Al x CoCr-CuFeNi4and Al x CrCuFeNi2systems are plotted in Fig.2.The electronegativity difference,D v,and VEC are also plot-ted to show how these factors referred in the Hume-Rotheryrule affect the solid solution formation.D H mix,D v and VECare all plotted as a function of d in Fig.2for convenience,and this does not indicate these parameters are mutually de-pendent.For comparison,d,D H mix,D v and VEC for threeadditional systems of HEAs[CoCrCuFeNiTi x(see Ref.13),Al0.5CoCrCuFeNiTi x(see Ref.14),Al0.5CoCrCuFeNiV x(see Ref.15)],where compounds will form in the originallyfcc-typed alloy by increasingly doping the amount of onealloying element(Ti or V),are also plotted in Fig.2.The cal-culation required physicochemical and thermodynamicFIG.1.(Color online)X-ray diffraction patterns for Al x CrCuFeNi2alloys(x¼0.2$1.2).FIG.2.(Color online)Relationship between the mixing enthalpy,D H mix(a),the Electronegativity,D v(b)and the valence electron concentration,VEC,(c),and the atomic size difference,d,forﬁve HEA systems:Al x CoCrCu-FeNi,CoCrCuFeNiTi x,Al0.5CoCrCuFeNiTi x,Al0.5CoCrCuFeNiV x,andAl x CrCuFeNi2.Note on the legend:fully closed symbols for sole fcc phases;fully open symbols for sole bcc phase;top-half closed symbols for mixes fccand bcc phases;left or right-half closed symbols for phases containing atleast one compound phase(left or right half simply indicates different typesof compounds).parameters for the constituent alloying elements are from Refs.16–19and some of them are listed in Table I .As seen from Fig.2,using the deﬁnitions of atomic size difference,mixing enthalpy,valence electron concentration and electronegativity deﬁned here,D H mix is the only effec-tive parameter that can predict the formation of sole solid solutions (hence no formation of compounds)in HEAs.Solid solution form when À5KJ/mol D H mix 5KJ/mol,and compounds would form once D H mix is more negative.On the other hand,d ,D v and VEC all fail to effectively predict the formation of solid solution phases or compounds.Figure 2provides some clues to obtain the solely solid solution struc-ture in HEAs based simply on the fundamental properties of constituent elements.This is certainly useful but from Fig.2it is still unclear when the bcc phase will form and what is the determining factor controlling the bcc phase formation.A careful examination of Fig.2,however,suggests that bcc phases start to form when VEC reaches $8.0[Fig.2(c)].The other three parameters,D H mix ,d ,and D v do not behave such a clear indicator function.To make the point clearer,VEC for three HEA systems,Al x CoCrCuFeNi (see Ref.4),Al x CoCrCu 0.5FeNi (see Ref.7),and Al x CoCrCuFeNi 2(this work)in which increasingly doping of the same element Al would cause phase constitution from sole fcc to mixed fccand bcc,are plotted in Fig.3.Figure 3clearly shows that VEC can be used to quantitatively predict the phase stability for fcc and bcc phases in HEAs:at VEC !8.0,sole fcc phase exists;at 6.87 VEC <8.0,mixed fcc and bcc phases will co-exist and sole bcc phase exists at VEC <6.87.Note that at the boundary VEC ¼8.0,sometimes bcc phases also form but they are minor phases (see Fig.1and Ref.4).Although there is one exception for the Al x CoCrCu 0.5FeNi alloy where 6.87 VEC <8.0but the stable phase is sole bcc (not fcc þbcc),we suspect this VEC -deﬁned phase stability shall work effectively for most cases.To prove this,VEC for more HEA systems with fcc,fcc þbcc,or bcc structure containing other alloying elements like Ti,V,Mn,Nb,Mo,Ta,W even metalloid B and C,are plotted in Fig.4(data are from litera-tures in Ref.7and 20–24).Although there are still some exceptions,the fcc/bcc phase boundary can clearly be delineated by VEC .With a note to those exceptions,the VEC -deﬁned fcc/bcc phase boundary seems to work unsatis-factorily for Mn-containing HEA systems.TABLE I.Physiochemical properties for commonly used elements in HEAs.Element Atom radius (A˚)Pauling electronegativityVEC Al 1.4321.613B 0.8202.043C 0.773 2.554Co 1.251 1.889Cr 1.249 1.666Fe 1.241 1.838Mn 1.350 1.557Mo 1.363 2.166Nb 1.429 1.65Ni 1.246 1.9110Ta 1.430 1.505Ti 1.462 1.544V 1.316 1.635W1.3672.366FIG.3.(Color online)Relationship between VEC and the fcc,bcc phase sta-bility for three HEA systems:Al x CoCrCuFeNi,Al x CrCuFeNi 2and Al x CoCr-Cu 0.5FeNi.Note on the legend:fully closed symbols for sole fcc phases;fully open symbols for sole bcc phase;top-half closed symbols for mixes fcc and bccphases.FIG. 4.(Color online)Relationship between VEC and the fcc,bcc phase sta-bility for more HEA systems further to Fig.3.Note on the legend:fully closed symbols for sole fcc phases;fully open symbols for sole bcc phase;top-half closed symbols for mixes fcc and bcc phases.IV.DISCUSSIONThe effect of the VEC on the phase stability has been studied before by the current authors for the intermetallic compounds only.One example is on the(Fe,Co,Ni)3V inter-metallic alloys with long-range-ordered(LRO)structures.25 We found that these LRO alloys are characterized by speciﬁc sequences of stacked close-packed ordered layers and the stacking character can be altered systematically by control-ling the VEC of these alloys.With the decreasing VEC by partial substitution of Co and Ni by Fe,the LRO changes from purely hexagonal,to L12-type cubic ordered structure, through different ordered mixtures of hexagonal and cubic layers.As the hexagonal structure exhibits brittle fracture while the cubic ordered structures are ductile,the control of VEC can hence be used to tune the mechanical properties of LRO alloys.We also investigated the role of VEC in the phase stability of NbCr2-based transition-metal Laves phase alloys.26It was found that when the atomic size ratios were kept nearly identical,the VEC is the dominant factor in con-trolling the phase stability(C14,hexagonal or C15,cubic)in this type of high-temperature structural alloys.Our results in the present work prove that VEC also plays a decisive role in the stability of fcc and bcc solid solution phases in the multi-component HEAs.Mizutani has shown that VEC is crucial in determining the Fermi level whenﬁrst-principles band calcu-lations are carried out to study the band structure.11In the ﬁrst-principles band calculations,the integration of the den-sity of states(DOS)actually results in VEC,which includes not only s-and p-electrons but also d-electrons forming the valence band.11Mizutani emphasized that the parameter VEC,instead of e/a,should be used in realistic electronic structure calculations to take into account the d-electron con-tribution.11More theoretical work needs to be carried out to understand the physical basis for the mechanism behind the VEC rule on the phase stability,for example from the VEC-electronic structure-bind structure energy perspective.27 Two issues need to be emphasized here for the discussion of the VEC rule on the phase stability.First,the VEC ranges for different phases to be stable might overlap and these ranges also vary depending on the speciﬁc alloy systems.A very close example is in some ternary Mg alloys that possess typical Laves structures.9It was found that the electron con-centration(e/a though)ranges for MgCu2-type(cubic,with packing ABCABCABC),MgNi2-type(hexagonal,with pack-ing ABACABAC)and MgZn2-type(hexagonal,with packing ABABAB)structures differ in various alloy systems,and the e/a ranges for MgNi2-type structure and MgZn2-type struc-ture overlap for the Mg-Cu-Al system.This can probably explain the exceptions that appear in Figs.3and4.Second, the phases referred in this work are all identiﬁed in the as-cast state and they are hence very possibly in the metastable state. However,evidences have shown that these metastable phases have quite good thermal stability28–31and can hence be regarded as very close to the stable phases.This gives conﬁ-dence to the general applicability of the VEC rule,consider-ing it works so well for such an extended series of various alloy systems.More work is certainly needed to further verify this.Admitting these two issues mentioned above,one solid result out of our study is that,in HEAs the bcc phase is stable at lower VEC while the fcc phase is stable at higher VEC. This trend already sheds some light on the alloy design,and the fact that most HEA alloy systems satisfying the VEC (<6.87,bcc;!8,fcc)rule even simpliﬁes the process.As the VEC rule on the phase stability between the fcc and bcc phases is tested only for the HEAs in this work,its applicabil-ity to other alloy systems other than the nearly equiatomic HEAs(i.e.,in the traditional alloys where only one or two pri-mary elements dominate),awaits further analysis.In addition, it would be interesting to know whether this VEC rule can be used to predict the phase stability for other structured phases, like the hcp-typed phases.More work along these directions is under way.V.CONCLUSIONSIn summary,the phase stability in HEAs and its relation-ship to the physicochemical and thermodynamic properties of constituent alloying elements are systematically studied. The mixing enthalpy determines whether the solid solution phases or compounds form in the nearly equiatomic multi-component alloy systems.Most importantly the VEC is found to be the physical parameter to control the phase sta-bility for fcc or bcc solid solutions.Fcc phases are found to be stable at higher VEC(!8)and instead bcc phases are sta-ble at lower VEC(<6.87).This work provides valuable input for understanding of the phase stability and to design ductile crystal structures in HEAs. ACKNOWLEDGMENTSThis research was supported by the internal funding from HKPU.1B.Cantor,I.T.H.Chang,P.Knight,and A.J.B.Vincent,Mater.Sci. Eng.A375,213(2004).2W.H.Wu,C.C.Yang,and J.W.Yeh,Ann.Chim.Sci.Mater.31,737(2006). 3J.W.Yeh,Ann.Chim.Sci.Mater.31,633(2006).4C.J.Tong,Y.L.Chen,S.K.Chen,J.W.Yeh,T.T.Shun,C.H.Tsau, S.J.Lin,and S.Y.Chang,Metall.Mater.Trans.36A,881(2005).5C.W.Tsai,M.H.Tsai,J.W.Yeh,and C.C.Yang,J.Alloys Compd.490, 160(2010).6F.J.Wang,Y.Zhang,and G.L.Chen,J.Alloys Compd.478,321(2009). 7G.Y.Ke,S.K.Chen,T.Hsu,and J.W.Yeh,Ann.Chim.Sci.Mater.31, 669(2006).8Y.Zhang,Y.J.Zhou,J.P.Lin,G.L.Chen,and P.K.Liaw,Adv.Eng. Mater.10,534(2008).9R.W.Cahn and P.Hassen,Physical Metallurgy,4th ed.(North Holland, Amsterdam,1996),Vol.1.10S.S.Fang,X.Xiao,X.Lei,W.H.Li,and Y.D.Dong,J.Non-Cryst.Sol-ids321,120(2003).11U.Mizutani,Hume-Rothery Rules for Structurally Complex Alloy Phases (CRC Press,Boca Raton,2011).12T.B.Massalski,Mater.Trans51,583(2010).13X.F.Wang,Y.Zhang,Y.Qiao,and G.L.Chen,Intermetallics15,357 (2007).14M.R.Chen,S.J.Lin,J.W.Yeh,S.K.Chen,Y.S.Huang,and C.P.Tu, Mater.Trans.47,1395(2006).15M.R.Chen,S.J.Lin,J.W.Yeh,S.K.Chen,Y.S.Huang,and M.H. Chuang,Metall.Mater.Trans.37A,1363(2006).16A.Takeuchi and A.Inoue,Mater.Trans.41,1372(2000).17A.Takeuchi and A.Inoue,Mater.Trans.46,2817(2005).18O.N.Senkov and D.B.Miracle,Mater.Res.Bull.36,2183(2001).19WebElements:the periodic table on the web,available at:http://www. /.20C.C.Tung,J.W.Yeh,T.T.Shun,S.K.Chen,Y.S.Huang,and H.C. Chen,Mater.Lett.61,1(2007).21H.Y.Chen,C.W.Tsai,C.C.Tung,J.W.Yeh,T.T.Shun,C.C.Yang, and S.K.Chen,Ann.Chim.Sci.Mater.31,685(2006).22O.N.Senkov,G.B.Wilks,D.B.Miracle,C.P.Chuang,and P.K.Liaw, Intermetallics18,1758(2010).23C.Li,J.C.Li,M.Zhao,L.Zhang,and Q.Jiang,Mater.Sci.Technol.24, 376(2008).24Y.F.Li,L.J.Kong,Z.H.Gan,and Z.X.Yuan,J.Wuhan,Univ.Sci. Technol.32,60(2009).25C.T.Liu,Inter.Met.Rev.29,168(1984).26J.H.Zhu,P.K.Liaw,and C.T.Liu,Mater.Sci.Eng.A239–240,260 (1997).27D.Nguyen-Manh and D.G.Pettifor,Intermetallics7,1095(1999).28L.H.Wen,H.C.Kou,J.S.Li,H.Chang,X.Y.Xue and L.Zhou,Interme-tallics17,266(2009).29C.M.Lin,H.L.Tsai,and H.Y.Bor,Intermetallics18,1244(2010).30C.M.Lin and H.L.Tsai,pd.489,30(2010).31O.N.Senkov,G.B.Wilks,J.M.Scott,and D.B.Miracle,Intermetallics 19,698(2011).。

电化学交流阻抗

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二价金属离子对磷脂聚集态的影响-北京大学教务部

二价金属离子对磷脂聚集态的影响The influence of divalent metal ions on the aggregation properties of EYPC化学与分子工程学院2000级俞科兵College of chemistry and molecular engineering Yu Kebing摘要主要通过浊度分析和激光光散射光谱研究了二价金属离子（Ca2＋、Cu2＋、Zn2+和Mn2＋）对卵磷脂(EYPC)聚集态的影响。

结果表明：自由的二价金属离子对EYPC囊泡有破坏作用，并使EYPC囊泡发生相转变，形成胶束；而与胆汁酸钠(NaTC，NaGC，NaTDC，NaDC)结合的二价金属离子使EYPC囊泡半径减小，但不破坏EYPC囊泡。

关键词: 卵磷脂，二价金属离子，胆盐，聚集态，紫外分析AbstractThe methods of light scattering and UV spectroscopy are applied to follow the effects of divalent metal ions on EYPC vesicles. We conclude free divalent metal ions act to precipitate unilamellar PC vesicles whereas, in combination with sodium taurocholate, sodium glycocholate, sodium deoxycholate or sodium deoxytaurocholate, these ions act to decrease the size of PC vesicles and some induce a phase transition from PC vesicles to mixed micelles.Keywords: phosphatidylcholine, divalent metal ions, bile salts, aggregation properties, UV-vis1．前言1.1 胆汁酸胆汁酸是胆汁中存在的一大类胆烷酸的总称，人体中由胆固醇合成而来。

半导体器件物理复习资料

半导体器件物理复习资料元素（Element）半导体：在周期表第Ⅳ族中的元素如硅（Si）及锗（Ge）都是由单一原子所组成的元素（element）半导体。

几种常见的晶体结构晶体：组成固体的原子（或离子）在微观上的排列具有长程周期性结构非晶体：组成固体的粒子只有短程序，但无长程周期性准晶：有长程的取向序，沿取向序的对称轴方向有准周期性，但无长程周期性能带的形成原子靠近→电子云发生重叠→电子之间存在相互作用→分立的能级发生分裂。

从另外一方面来说，这也是泡利不相容原理所要求的。

一个能带只能有N个允许的状态；考虑电子有两种自旋状态，故一个能带能容纳2N个电子；对于复式格子，每个能带允许的电子数还要乘上原胞内的原子个数；对于简并能带，状态总数要乘以简并度。

金属、半导体、绝缘体金属导体：最高填充带部分填充；绝缘体和半导体：T=0K，最高填充带为填满电子的带。

T>0K，一定数量电子激发到上面的空带。

绝缘体的Eg大，导带电子极少；半导体的Eg小，导带电子较多。

根据能带填充情况和Eg大小来区分金属、半导体和绝缘体。

（全满带中的电子不导电；部分填充带：对称填充，未加外场宏观电流为零。

加外场，电子逆电场方向在k空间移动。

散射最终造成稳定的不对称分布，产生宏观电流（电场方向）。

）有效质量电子共有化运动的加速度与力的关系和经典力学相同，即：m*具有质量量纲，称为晶体中电子的有效质量。

（能带越宽，有效质量越小；能带越窄，有效质量越大。

）m*的意义：晶体中的电子除受到外力，还受到周期场力。

引入m*，可得出外力F和加速度a的简单关系，把复杂的周期场力包括到m*中去了。

引入共有化运动速度和有效质量后，可将晶体中的电子视为经典粒子，将其运动规律等效成自由电子运动规律。

硅及砷化镓的能带结构。

圆圈(○)为价带中的空穴，黑点(•)为导带中的电子。

本征载流子浓度本征半导体：在恒温下，连续的热扰动造成电子从价态激发到导带，同时在价带上留下等量的空穴。

离散元在锂离子电池中的应用

离散元在锂离子电池中的应用Discrete element method (DEM) has been widely used in various fields, including the study of lithium-ion batteries (LIBs). 离散元方法（DEM）已经被广泛应用于各个领域，包括锂离子电池（LIBs）的研究。

DEM provides a powerful tool for analyzing the mechanical behavior of electrode materials in LIBs, helping researchers gain valuable insights into the performance and safety of these energy storage devices. DEM为分析LIBs中电极材料的机械行为提供了一个强大的工具，帮助研究人员获取宝贵的见解，以提高这些能量存储设备的性能和安全性。

One of the key advantages of using DEM in the study of LIBs is its ability to simulate the complex interactions between individual particles within the electrode materials. 使用DEM研究LIBs的一个关键优势是它能够模拟电极材料中个体颗粒之间复杂的相互作用。

By considering the discrete nature of these particles, DEM can accurately capture the effects of particle size, shape, and distribution on the overall mechanical behavior of the electrodes. 通过考虑这些颗粒的离散性质，DEM可以准确捕捉颗粒大小、形状和分布对电极整体机械行为的影响。

多弧离子镀

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有重要意义。传统的表面强化技术，包括表面热处理、表面渗碳及油漆技术等，这些技
┊
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术对某些零件和工具虽可解决部分问题，但却难以从根本上满足其高速、重载、长寿命
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的要求。导致在工程和机械的实际应用中，一些在高温、冲击、重载、强腐蚀介质等恶
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1.2.3 TiAlN 薄膜的特点 ............................................. 8
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订
1.2.4 TiAlN 薄膜的结构 ............................................. 8
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1.2.5 TiAlN 薄膜的性能 ............................................. 9
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method(L18).
装
The results show that the process of deposition has been effected by parameters.The
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performance of TiAlN coating is restricted by nitrogen pressure, target power, pretreat voltage
安徽工业大学
毕业设计（论文）报告纸
多弧离子镀 TiAlN 工具膜的工艺优化及性能评估
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摘要
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本研究的目的是优化多弧离子镀 TiAlN 薄膜的制备工艺。用扫描电镜进行薄膜表面
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形貌观察，用 X 射线衍射仪表征组织结构，用划痕仪研究膜-基结合力，用纳米压痕仪
┊

Al含量对TiAlN涂层的组织和抗氧化性能的影响

ｉｇｔｎｔａｉＴｏ５１４）ｏｔｇＴｏ１６Ｎｃａｉａｅｅｘｄｔｎｒｓｔｎｅｔａｎａｔｎ（ｉ５０５Ｎｃａｎ．（ｉ４０）ｏｔｇｈｄｂｔｒｏｉａｏｅｉａｃｈｎｈｈ．ＡｉＡ．ｎｔｉｓ
ｈｄｓｌｅａｔｅｐｒｍｅｅ，ｌｒｅａｔｅｄｅｏｍａｉｎａｄｈｇｅｃｏｈｒｎｓ．Ｃｏａｅｔａｍａｌｒｌｔｃａａｔｒａｇｒｌｔｃｆｒｔｎｉｈｒｍｉｒ — ａｄｅｓｉｉｏｍｐｒｄｗｉｈ
【摘要】采用阴电弧蒸发镀在ＷＣＣ硬质合金基体表面沉积两种不同Ａ含量的（ｉ极 —ｏ１ＴＡＮ涂层，１）比较了（ｊＡ０）Ｔ。１６Ｎ涂层和（ｊ１）ｌＴ。。Ｎ涂层的组织和抗氧化性能。结果表明：Ａ两
．
种涂层的主要相都是呈ＮＣ型面心立方结构的ＴＮＴ０１Ｎ涂层晶格常数较小，ａ１ｉ。（Ａ。ｉ）固溶强化
第３２卷
第３期
上
海
金
属
Ｖｏ．２，Ｎｏ３１３．Ｍａ，２１ｙ００１１
２１００年５月
ＳＨＡＮＧＨＡＩＭＥＴＳＡＬ
Ａ含量对ＴＡＮ涂层的组织和抗氧化性能的影响ｌｉ１
陈佳荣朱丽慧。倪旺阳刘一雄
（．１上海大学上海市现代冶金及材料制备重点实验室，上海２０７；．国宾夕法尼亚州ＫｎａｅａＩｃ）００２２美ｅｎｍｔｌｎ．

多晶硅硅扩散工艺流程

多晶硅硅扩散工艺流程英文回答：Silicon diffusion is a crucial process in the fabrication of multi-crystalline silicon (mc-Si) solar cells. It involves the introduction of impurities into the silicon wafer to create regions with different electrical properties, such as p-type and n-type doping. This allows for the formation of pn junctions, which are essential for the functioning of solar cells.The silicon diffusion process typically consists of several steps, including cleaning, surface passivation, and doping. Let me walk you through each step in more detail.First, the silicon wafer is thoroughly cleaned to remove any contaminants or oxides on the surface. This is usually done using a combination of chemical etching and rinsing with deionized water. The goal is to create a clean and smooth surface for subsequent processing steps.Next, a thin layer of passivation material is deposited on the wafer surface. This passivation layer helps to reduce surface recombination and improve the overall efficiency of the solar cell. Common passivation materials include silicon nitride (SiNx) and aluminum oxide (Al2O3).After passivation, the wafer is ready for the diffusion step. This is where the impurities are introduced into the silicon lattice to create the desired doping profile. The most commonly used dopants for mc-Si solar cells are phosphorus (P) for n-type doping and boron (B) for p-type doping.One technique commonly employed for silicon diffusion is the use of a dopant source, such as a phosphorus or boron-containing gas. The wafer is placed in a diffusion furnace, and the dopant gas is introduced at high temperatures. The dopant atoms diffuse into the silicon lattice, replacing some of the silicon atoms and creating the desired doping profile.The diffusion process is typically carried out at temperatures ranging from 800 to 1100 degrees Celsius, depending on the specific dopant and desired doping profile. The duration of the diffusion process also varies, but it can range from a few minutes to several hours.Once the diffusion is complete, the wafer is then subjected to various annealing and activation steps to activate the dopants and repair any defects introduced during the diffusion process. These steps help to improve the electrical properties of the solar cell and optimizeits performance.In summary, the silicon diffusion process in mc-Sisolar cell fabrication involves cleaning, passivation, and doping steps. It is a critical process that determines the electrical properties of the solar cell and its overall performance.中文回答：多晶硅硅扩散是光伏电池制造过程中的关键步骤之一。

B对Mo等合金元素在γ-Fe_∑9、∑11晶界偏析行为的影响

γ-Fe ∑9(221)对称倾转晶界是 γ-Fe(221)面以 [110]晶向为旋转轴,将两部分晶体旋转 38.94°所构成,γ-Fe ∑11(113)对称倾转晶界是 γ-Fe(113)面以[110]晶向为旋转轴,将两部分晶体旋转 129.52° 所构成(见表1)。两个晶体的叠加导致两个晶格的子晶格的位置重合,距离太近的位点将被合并。本文 γ-Fe∑9(221)晶界中含36个 Fe原子,初始晶胞尺寸0.243nm×0.729nm×2.062nm,γ-Fe ∑11 (113)晶界中含44个 Fe原子,初始晶胞尺寸0.243 nm×0.806nm×2.280nm,α=β=γ=90°,首先对 γ-Fe ∑9(221)、γ-Fe ∑11(113)晶界体系进行结构
compositionoptimizationofsuperausteniticstainlesssteelinthefuture. Keywords:Fe;first-principles;grainboundary;segregation
超级奥氏体不锈钢中含有大量的合金元素,如 Cr、Mn、Ni、Mo、Cu、Si等,其中 Cr、Mo等是铁素体形成元素 ,Ni、Mn、Cu 等是奥氏体形成元素 ,可以扩大并稳定奥氏体相区。 [1-4] 相对于普通的奥氏体不锈钢 ,超级奥氏体不锈钢在耐晶间腐蚀、点蚀等方面表现更为优异[5-7],因此被广泛应用于烟气脱硫、石油化工、海水淡化等领域。 [8-11] 然而,在热加工过程中 ,由于合金元素较多 ,超级奥氏体不锈钢中的合金元素极易发生晶界偏析 ,并形成大量的第二相 ,引发开裂、分层等问题 ,严重制约了超级奥氏体不锈钢的生产及应用。因此,如何有效改善 Cr、Mo等合金元素的晶界偏析、遏制第二相的析出成为目前研究的热点。

Al晶界中Ti杂质效应的第一性原理计算

Ｆｉｓ— ｉｃｐｌｓｃｌｕａｉｎｏｈｆｅｔｆｔｔｎｕｒｔｐｒｎｉｅａｃｌｔｏｆｔｅｅｆｃｓｏｉａｉｍｉｐｕｉｙｏｎａｕｉｍｒｉｕａｙｍｒｔｎａｌｍｎｕｇａｎｂｏｎｄｒ
理论研究。如Ｇｏｅｉｏｄｗｎ等］第一次用密度泛函
理论方法计算和研究了Ｇ和Ａｓｅ等杂质元素对
面，杂质的偏析使金属母原子与偏析杂质原子间的
内聚力减弱而引起材料的脆化，一机制称为 “ｅ这ｄ— ｃｈｓｎｍｏｅ；ｏｅｉｄｌ另一方面，ｏ ” 杂质的偏析可能会在金属母原子与杂质原子之间形成具有共价性质的强化学键，到外界应力时，域的强化学键会抑受局制或削弱材料的位错形成和延展特性，而产生脆从
杂质对材料性能的影响问题在材料科学中一
ＣＥ的掺杂等。ａＴ］关于中杂质偏析问题，有一些人进行了也
直倍受关注，该方面的研究工作具有重要的现实意义。１７，ｏｃＥ首先提出，的引入可以改９９年Ｌｓｈ１＿杂质
变金属的电子结构，而导致金属的脆化。一方从
ＡｂｔａｔＴｈｔｍｉａｄｅｅｔｏｉｔｕｔｒｓｏｎＡ１ｉｒｉｏｎａｙｗｉｅｒｇｔｄｔｔｎｕｓｒｃ：ｅａｏｃｎｌｃｒｎｃｓｒｃｕｅｆ￣９ｔｔｇａｎｂｕｄｒｔｓｇｅａｅｉｉｍａｌｈａｉｐｒｔｔｍｓａｅｃｌｕａｅｙａｆｒｔｐｉｃｐｅｓｕｏｏｅｔｌｍｅｈｄｂｓｄｏｈｏａｅｓｔｍｕｉａｏｒａｃｌｔｄｂｉｓ— ｒｎｉｌｓｐｅｄｐｔｎｉｔｏａｅｎｔｅｌｃｌｄｎｉｙｙａｆｎｔｎｌｈｏＮＴｈｅｕｔｎｉａｅｔａｈｏｎａｙｅｐｎｓａｄｔｅｃａｇｅｓｔｃｅｓｓｏｕｃｉａｅｒｏｔｅｒｓｌｉｄｃｔｈｔｔｅｂｕｄｒｘａｄｎｈｈｒｅｄｎｉｙｉｒａｅｎｓｎｔｅｂｕｄｒａｄｔａｔｏｇｒｃｖｌｎ－ｔｌｃｃａａｔｒｍｉｇｂｎｓｂｔｅｈｐｒｔｔｍｓｈｏｎａｙ，ｎｈｔｓｒｎｅｏａｅｔｍｅａｌｈｒｃｅ￣ｎｏｄｅｗｅｎｔｅｉｕｉｙａｏｉｍａｄｔｅｎｉｈｏｉｇＡ１ｔｍｓａｅｆｒｅ，ＳｈｍｂｉｔｉｇｍｅｈｎｓｃｎｂｌｓｉｅｔｈｏｄｎｈｅｇｂｒｏｒｏｍｄＯｔｅｅｒｔｌｃｔｏｅ．ｂｌｙｍｄ１ｉＫｅｒｓｌｍｉｉｍｒｉｏｎａｙｙｗｏｄ：ａｕｎｕｇａｎｂｕｄｒ；Ｔｉｉｐｒｔ；ｆｓ－ｒｎｉｌｓｍｕｉｙｉｔｐｉｃｐｅｒ

【35】金修饰在聚咪唑修饰的玻碳电极同时检测多巴胺尿素等

Analytica Chimica Acta 741 (2012) 15–20Contents lists available at SciVerse ScienceDirectAnalytica ChimicaActaj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /a caSimultaneous determination of ascorbic acid,dopamine,uric acid and tryptophan on gold nanoparticles/overoxidized-polyimidazole composite modiﬁed glassy carbon electrodeCun Wang,Ruo Yuan ∗,Yaqin Chai,Shihong Chen,Fangxin Hu,Meihe ZhangEducation Ministry Key Laboratory on Luminescence and Real-Time Analysis,College of Chemistry and Chemical Engineering,Southwest University,Chongqing 400715,Chinah i g h l i g h t sThe electropolymerization of imida-zole (Im)on GCE was ﬁrst reported. The PIm ﬁlm can be overoxidized to form the overoxidized polyimidazole (PImox).PImox allows dispersing of Au and generates additional electrocatalytic sites. The overlapping voltammetric response of AA,DA,UA and Trp is well-resolved.g r a p h i c a la b s t r a c tElectropolymerization of Im on the GCE,the PIm modiﬁed electrode was denoted as PIm/GCE.Subse-quently,the PIm/GCE was washed with doubly distilled water,and then transferred to 0.1M PBS (pH 4.0)for electrochemical oxidation at +1.8V for 250s.The obtained electrode was denoted as PImox/GCE (Fig.A).Then,the deposition of GNPs on PImox/GCE was carried out.The obtained electrode was described as GNPs/PImox/GCE (Fig.B).a r t i c l ei n f oArticle history:Received 13March 2012Received in revised form 18June 2012Accepted 19June 2012Available online 4 July 2012Keywords:ImidazoleGold nanoparticles Ascorbic acid Dopamine Uric acid Tryptophana b s t r a c tA novel electrode was developed through electrodepositing gold nanoparticles (GNPs)on overoxidized-polyimidazole (PImox)ﬁlm modiﬁed glassy carbon electrode (GCE).The combination of GNPs and the PImox ﬁlm endowed the GNPs/PImox/GCE with good biological compatibility,high selectivity and sensi-tivity and excellent electrochemical catalytic activities towards ascorbic acid (AA),dopamine (DA),uric acid (UA)and tryptophan (Trp).In the fourfold co-existence system,the peak separations between AA–DA,DA–UA and UA–Trp were large up to 186,165and 285mV,respectively.The calibration curves for AA,DA and UA were obtained in the range of 210.0–1010.0␮M,5.0–268.0␮M and 6.0–486.0␮M with detection limits (S/N =3)of 2.0␮M,0.08␮M and 0.5␮M,respectively.Two linear calibrations for Trp were obtained over ranges of 3.0–34.0␮M and 84.0–464.0␮M with detection limit (S/N =3)of 0.7␮M.In addition,the modiﬁed electrode was applied to detect AA,DA,UA and Trp in samples using standard addition method with satisfactory results.© 2012 Elsevier B.V. All rights reserved.1.IntroductionAscorbic acid (AA)is very popular for its antioxidant property,and present in the human diet as a vital vitamin.Moreover,it is∗Corresponding author at:College of Chemistry and Chemical Engineer-ing,Southwest University,Chongqing Key Laboratory of Analytical Chemistry,Chongqing,400715,PR China.Tel.:+862368252277;fax:+862368253172.E-mail address:yuanruo@ (R.Yuan).also used for the prevention and treatment of common cold,men-tal illness,infertility,cancer and AIDS [1].Dopamine (DA)is one of the most signiﬁcant catecholamines.It plays a very important role in the functioning of the central nervous,cardiovascular,renal and hormonal systems as well as in drug addiction and Parkin-son’s disease [2].Uric acid (UA)is the primary end product of purine metabolism.Abnormal levels of UA are symptoms of several diseases,including gout,hyperuricemia and Lesch Nyan disease [3,4].Tryptophan (Trp)is an essential amino acid for human and0003-2670/$–see front matter © 2012 Elsevier B.V. All rights reserved./10.1016/j.aca.2012.06.04516 C.Wang et al./Analytica Chimica Acta741 (2012) 15–20herbivores[5].In addition,it has been implicated as a possible cause of schizophrenia in people who cannot properly metabo-lize it[6].It is known to all,AA,DA,UA and Trp usually coexist in biological samples.Therefore,a sensitive and selective method for their simultaneous determination is highly desirable for analyt-ical application and diagnostic research.A major problem for their simultaneous determination is that AA,DA,UA and Trp undergo the same potential at conventional electrodes with a pronounced foul-ing effect,resulting in poor reproducibility.Besides,many reported detection methods were complicated,expensive,and suffered from sensitivity as well as selectivity.To overcome these problems,many materials have been employed to modify electrodes,such as gold nanocluster/overoxidized-polypyrrole composite[7]and iron(III) doped zeolite[5].Recently,polymerﬁlm and metal nanoparticles have been arose great attentions due to their wide applications in theﬁelds of chemical modiﬁed electrodes[8,9].As is well-known,metal nanoparticles especially gold nanoparticles(GNPs)can enhance the conductivity,facilitate the electron transfer and improve the detection limit of electrode[10].Among various types of conduc-tive polymers[11–14],polyimidazole(PIm)has many attractive features,for example theﬁlm is very stable and hard to be taken off from the surface unless the electrode is heavily polished.It has high selectivity and sensitivity due to the chemically stable homogeneousﬁlm with controlled thickness[12].Furthermore, the PImﬁlm can be further overoxidized at higher potentials to form the overoxidized-polyimidazole(PImox),resulting in an insulating membrane with lower background current.The overox-idizedﬁlm has large surface area because of the porous structure. Moreover,the porous structure of the PImoxﬁlm is in favor of dispersing metal nanoparticles into the polymer matrix and gener-ates additional electrocatalytic sites[7,15].Since the combination of the polymerﬁlms and metal nanoparticles not only signiﬁ-cantly improve the electrocatalytic properties of substrates and the stability and reproducibility of the electrode but also decrease the overpotential and increase the reaction rate[14].For exam-ple,gold nanocluster/overoxidized-polypyrrole composite[7]and overoxidized poly(N-acetylaniline)[16]modiﬁed electrodes have been used for the determination of DA or serotonin.However, compared with the methods mentioned above,the modiﬁed electrode in our work exhibits its peculiar advantages,such as higher sensitivity,selectivity,reproducibility and relatively low cost.In this study,a novel electrode based on the PImoxﬁlm incorporated with GNPs was constructed for the simultaneous determination of AA,DA,UA and Trp.Due to the synergic effect between PImox and GNPs,the overlapping voltammetric response of AA,DA,UA and Trp is well-resolved from each other with lowered oxidation pared with the GNPs/GCE,PIm/GCE and PImox/GCE,the GNPs/PImox/GCE exhibited obviously enhanced responses towards AA,DA,UA and Trp.Furthermore,the practi-cal application was investigated using standard addition method and satisfactory results were obtained.2.Materials and methods2.1.ChemicalsChloroauric acid(HAuCl4)and imidazole(Im)were pur-chased from Sigma Chemical Co.(St.Louis,Mo,USA).Sodium dodecylsulfate(SDS),uric acid,tryptophan,ascorbic acid and dopamine were purchased from Chemical Reagent Co.(Chongqing, China).Phosphate buffer solutions(PBS)(0.1M)at various pH were prepared using0.1M Na2HPO4,0.1M KH2PO4,and 0.1M KCl.Double-distilled water was used throughout the experiments.2.2.ApparatusAll electrochemical experiments were performed with a CHI 660D electrochemical workstation(Shanghai Chenhua Instrument Co.,China).The conventional three-electrode system included a modiﬁed glassy carbon electrode(GCE)as working electrode,a platinum wire as auxiliary electrode and a saturated calomel electrode(SCE)as a reference electrode.The morphological char-acterization of theﬁlms was examined by scanning electron microscope(SEM,S-4800,Hitachi,Japan).All measurements were carried out at room temperature.2.3.Preparation of GNPs/PImox modiﬁed electrodeThe glassy carbon electrode(diameter4.0mm)was successively polished to a mirror using0.3and0.05␮m alumina slurry.After-ward,the electrode was washed thoroughly with ethanol and water and dried at room temperature.Electropolymerization of Im on the GCE was carried out by8 circles between–0.2and0.8V at0.1V s–1in0.1M SDS containing 0.1M Im[14].The SDS was used as assisted reagent and support-ing electrolyte for the electropolymerization of Im[14].Moreover, the SDS could form a complex with Im,resulting in porous struc-ture with a large surface area[14,17].Eight circles were chosen to deposit the Imﬁlm because the highest sensitivity towards the biomolecules was obtained under this case(Fig.1S).Subsequently, the PIm modiﬁed electrode(PIm/GCE)was washed with double distilled water,and then transferred to0.1M PBS(pH4.0)for elec-trochemical oxidation at+1.8V to250s,obtaining PImox modiﬁed electrode(PImox/GCE).The deposition of GNPs on PImox/GCE was carried out in a mixture of H2SO4(0.5M)and HAuCl4(1mM)at –0.2V for80s[9].The80s was the optimal deposition time accord-ing to our studies(Fig.2S).The obtained electrode was described as GNPs/PImox/GCE.For comparison,PIm/GCE,PImox/GCE and GNPs/GCE were pre-pared using the same procedure.3.Results and discussion3.1.SEM of the modiﬁed electrodeThe morphology of modiﬁedﬁlms was investigated by scanning electron microscopy(SEM).As shown in Fig.1A,PImoxﬁlm appears a comparatively smooth and homogeneous surface.However,after electrodepositing GNPs,ﬂower-like nanostructures were observed in Fig.1B,indicating that GNPs were obtained.As seen from Fig.1B, the particle size of theﬂower-like GNPs was ranging from250to 450nm.Also,the GNPs look very pretty,and the keen-edged leaves make the surface of GNPs very rough and many leaves possess a large speciﬁc surface area.The results indicated that the PImox and GNPs/PImoxﬁlms were effectively immobilized on the electrode surface.3.2.The inﬂuence of pH on the oxidation of AA,DA,UA and Trp at the GNPs/PImox/GCEThe effect of pH value for the simultaneous determination of AA, DA,UA and Trp at GNPs/PImox/GCE was thoroughly investigated by differential pulse voltammetry(DPV).Fig.2showed the effect of pH value on the peak current and peak potential.From Fig.2A,the peak current of AA and Trp initially increased and reached a maximum value at pH4.0,then,another maximum value was observed at neu-tral pH with pH increasing.DA and UA give the highest response at pH4.0with pH increasing.The reason may be related to the change in electrostatic interaction between the four substances and GNPs/PImoxﬁlm.In Fig.2B,the linear regression equations for AA,C.Wang et al./Analytica Chimica Acta741 (2012) 15–2017Fig.1.SEM images of(A)PImox/GCE and(B)GNPs/PImox/GCE.DA,and Trp were obtained as:E DA(mV)=421.30–18.08pH,E UA (mV)=628.59–27.23pH and E Trp(mV)=789.21–17.37pH.All the peak potentials of AA,DA,UA and Trp shifted to more negative val-ues with the pH increasing.This is a consequence of a deprotonation step involved in all oxidation processes that is facilitated at higher pH values[18].AA(p K a=4.10),DA(p K a=8.87),UA(p K a=5.7)and Trp(p K a=5.89)exist as cationic form in pH4.0PBS(0.1M)[12]. Moreover,overoxidation in the Im ring leads to effective collection of the cationic species[7,19].It was expected that cationic forms of AA,DA,UA and Trp were electrostatically interacted with the poly-mer backbone at pH4.0[12].In addition,the maximum separation of peak potentials for AA–DA,DA–UA and UA–Trp is observed at pH 4.0.In order to obtain a high sensitivity and selectivity,pH4.0PBS (0.1M)was selected for further experiments.3.3.Cyclic voltammetric behaviors of the modiﬁed electrodeFig.3A showed the cyclic voltammograms(CVs)of different modiﬁed electrodes in0.1M PBS(pH4.0).As seen from Fig.3A, PImox/GCE(curve b)showed almost the same background current with the bare GCE(curve a),indicating anodic polarization at+1.8V maybe turn the PImﬁlm into an insulating PImoxﬁlm with the loss of electroactivity[20].However,after modiﬁed with GNPs,the background signal increased for GNPs/PImox/GCE(curve c),and this may be resulted from the larger effective surface area of GNPs. The inset Fig.3A showed the electropolymerization process.The Fig.2.Effect of pH on(A)the peak current and(B)the peak potential for the oxi-dation of150␮M AA,15␮M DA,80␮M UA and80␮M Trp in0.1M PBS(pH4.0). DPV conditions:scan rate,20mV s–1;amplitude,50mV;pulse width,50ms;pulse period,200ms.anodic peak potentials tended to be stable after8circles,suggesting a self-adjustment of the polymerﬁlm thickness at the GCE[21,22].The ability of GNPs/PImox/GCE to promote the voltammetric resolution of AA,DA,UA and Trp was investigated.Control exper-iments for the simultaneous determination of AA,DA,UA and Trp were carried out by CV at PIm/GCE,PImox/GCE,GNPs/GCE and GNPs/PImox/GCE,respectively.As can be seen from Fig.3B, PIm/GCE(curve a)and GNPs/GCE(curve c)only showed a broad and overlapped anodic peaks in the fourfold mixture.On the PImox/GCE (curve b)three peaks appeared at295,485and795mV for DA, UA and Trp,respectively,but simultaneous determination of AA, DA,UA and Trp could not be obtained due to the indistinguish-able and small response to AA.In contrast,the modiﬁcation of the GCE surface with GNPs/PImoxﬁlm(curve d)resolved the merged voltammetric peak into four well-deﬁned peaks at poten-tials around136,320,485and770mV with a remarkable increase in peak current for AA,DA,UA and Trp,respectively.The reasons for the oxidation of AA,DA,UA and Trp at a wide potential sep-aration are ascribed as follows:Firstly,the GNPs enhanced the catalytic activity of PImox/GCE by increasing the peak current due to the increasing electronic conductivity and effective surface area [21].Secondly,during the overoxidization process,higher density of groups such as C O,COO−,C OH and OH can be generated on the backbone of PImoxﬁlm.The existence of C O,COO−,C OH and OH on the PImoxﬁlm could provide a selective interface18 C.Wang et al./Analytica Chimica Acta 741 (2012) 15–20Fig.3.(A)CV responses of (a)bare GCE,(b)PImox/GCE and (c)GNPs/PImox/GCE in 0.1M PBS (pH 4.0).Inset of part (A)shows the CVs of polymerization of Im (0.1M)in 0.1M SDS solution on GCE in the potential range from –0.2to 0.8V.Scan rate,0.1V s –1;8circles.(B)CVs at (a)PIm/GCE,(b)PImox/GCE,(c)GNPs/GCE and (d)GNPs/PImox/GCE in 0.1M PBS (pH 4.0)containing 200␮M AA,20␮M DA,50␮M UA and 50␮M Trp.for the molecular interaction of AA,DA,UA and Trp via hydro-gen bonds with the proton-donating group such as NH and OH [15,16,21].Thirdly,AA,DA,UA and Trp exist as cationic form at pH 4.0.In addition,overoxidation in the Im ring leads to an effective rejection of the anionic species and preferential collection of the cationic species [19,23].It was expected that protonated forms of AA,DA,UA and Trp were electrostatically interacted with the poly-mer backbone.Thus,it effectively catalyzed the oxidation of four substances at low pH.Fourthly,the selective promising feature of PImox ﬁlm especially the composite with GNPs imparted superior selectivity and sensitivity towards the AA,DA,UA and Trp [13].In a word,the synergic effect of PImox ﬁlm and the GNPs endowed the GNPs/PImox/GCE with a lower detection limit,wider linear range,better electricity and higher selectivity and sensitivity than that of other electrodes in the literature (Table 1).3.4.Simultaneous determination of AA,DA,UA and TrpDPV was employed to detect AA,DA,UA and Trp because of its higher current sensitivity and better resolution than CV.In four-fold mixture,the electro-oxidation processes of AA,DA,UA and Trp in the mixture were investigated when the concentration of one species changed,whereas those of other three species are kept con-stant.Fig.4A depicted the DPV of AA containing 50␮M UA,15␮M DA and 50␮M Trp.The peak current of AA increased linearly with an increase in AA concentration from 210.0to 1010.0␮M,with theT a b l e 1C o m p a r i s o n o f t h e r e s p o n s e c h a r a c t e r i s t i c s o f d i f f e r e n t m o d i ﬁe d e l e c t r o d e s .E l e c t r o d e m a t e r i a l sL i n e a r r a n g e (␮M )D e t e c t i o n l i m i t (␮M )P e a k p o t e n t i a l (V )R e f e r e n c eA AD AU AT r pA AD AU AT r pA AD AU AT r pF e 3+Y /Z C M E 0.6–100–0.3–7000.2–1500.21–0.080.06––––[5]M W C N T –F e N A Z –C H 7.77–8337.35–8330.23–83.30.074–34.51.111.050.0330.011––––[6]G N P /c h o l i n e –0.2–801.2–100––0.120.6––0.230.37–[9]2-a m i n o -1,3,4-t h i a d i a z o l e 30–3005–5010–100–2.010.330.19–0.200.330.49–[12]O v e r o x i d i z e d p o l y (N -a c e t y l a n i l i n e )–0.50–20.0–––0.0168–––0.12––[24]p o l y -c h r o m o t r o p e 2B –2.0–80.0–––0.30–––0.349––[25]G N P s /P I m o x210.0–1010.05.0–268.06.0–486.03.0–34.084.0–464.02.00.080.50.70.1360.3200.4850.770T h i s w o r kC.Wang et al./Analytica Chimica Acta741 (2012) 15–2019Fig.4.DPVs at the GNPs/PImox/GCE in0.1M PBS(pH4.0)(A)containing50␮M UA,15␮M DA,50␮M Trp and different concentrations of AA(from inner to outer):210, 310,460,610,710,810,960,1010␮M;(B)containing100␮M AA,50␮M UA,50␮M Trp and different concentrations of DA(from inner to outer):5,10,18,28,38,88,168, 268␮M;(C)containing100␮M AA,15␮M DA,50␮M Trp and different concentrations of UA(from inner to outer):6,11,36,86,166,266,366,486␮M and(D)containing 150␮M AA,20␮M UA,5␮M DA and different concentrations of Trp(from inner to outer):3,6,11,19,34,84,164,314,464␮M.Insets:plots of Ip vs.concentration for AA, DA,UA and Trp,respectively.linear function I p,AA(␮A)=23.02+0.01584C AA(␮M)(R=0.9975),and a detection limit of2.0␮M(S/N=3).Fig.4B illustrated the DPVof DA containing100␮M AA,50␮M UA and50␮M Trp.The linearrelationship between the peak current and the concentration of DAwas obtained in the concentration range of5.0to268.0␮M.Thelinear function was expressed as I p,DA(␮A)=17.26+0.07882C DA(␮M)(R=0.9827),and a detection limit of0.08␮M(S/N=3)wasobtained.Similarly,Fig.5C depicted the DPV response of UAinFig.5.DPVs of simultaneous determination of AA,DA,UA and Trp using GNPs/PImox modiﬁed GCE in0.1M PBS(pH4.0).Concentrations of the four compounds:AA(60, 120,180,280,380,480,680,920␮M),DA(5,10,15,20,25,30,40,60␮M),UA(5, 10,15,20,28,36,54,63␮M)and Trp(5,10,15,20,25,30,40,60␮M).the presence of100␮M AA,15␮M DA and50␮M Trp,which exhibited a linear relationship in the concentration range of6.0–486.0␮M,and its linear regression equation was deﬁned asI p,UA(␮A)=10.59+0.03220C UA(␮M)(R=0.9898).The detection limit of0.5␮M(S/N=3)for UA was observed.Fig.5D illustrated the DPV of Trp containing50␮M AA,20␮M UA and5␮M DA.Two lin-ear calibration ranges of3.0–34.0␮M,with the linear function I p,Trp (␮A)=9.549+0.2414C Trp(␮M)(R=0.9362)and84.0–464.0␮M, and the linear function I p,Trp(␮A)=18.18+0.03716C Trp(␮M) (R=0.9632)were obtained for the Trp determination.The detec-tion limit was found to be0.7␮M(S/N=3).The relative standard deviations(RSD)for determining AA,DA,UA and Trp(n=10)were 7.09%,4.37%,5.67%and2.23%,respectively.The drift of the oxida-tion peaks of AA,DA,UA and Trp were observed for further addition of the respective analytes.In addition,DPVs were also performed at GNPs/PImox/GCE while changing the concentrations of AA,DA, UA and Trp simultaneously(Fig.5).3.5.Interferences,stability and reproducibilityIn order to evaluate the ability of anti-interference,several com-pounds were selected.It was found that no signiﬁcant interference for the detection of AA(150␮M),DA(10␮M),UA(50␮M)and Trp(50␮M)was observed for these compounds:NaCl,KCl,KNO3, CaCl2,MgSO4,ZnCl2,methenamine,ethylenediaminetetraacetic acid disodium salt,glucose,l-cysteine,glutathione,folic acid and levodopa.Stability of the GNPs/PImox/GCE was also investigated. The modiﬁed electrode was stored at room temperature when not used.The response of the electrode lost approximately6.3%,20 C.Wang et al./Analytica Chimica Acta741 (2012) 15–20Table2Determination of AA,DA,UA and Trp in dopamine hydrochloride injection,vitamin C tablets,human urine and serum samples.Sample Detected a(␮M)Added(␮M)Found a(␮M)Recovery(%) Urine1Uric acid36.3±1.710.045.0±1.397.2Ascorbic acid40.039.8±1.199.5Dopamine0.50.5±0.02100.0tryptophan30.030.5±0.7101.7Urine2Uric acid26.8±1.120.046.4±0.999.1Ascorbic acid80.081.3±2.4101.6Dopamine 2.5 2.4±0.196.0tryptophan40.040.1±1.0100.3 Serum1Uric acid12.1±0.415.026.8±0.698.9Ascorbic acid100.0100.2±3.7100.2Dopamine 2.0 1.9±0.195.0tryptophan50.050.2±1.8100.4 Serum2Uric acid13.6±0.620.035.0±0.9104.2Ascorbic acid150.0148.2±4.598.8Dopamine 1.0 1.0±0.04100.0tryptophan40.039.8±1.099.5 Vitamin C tablets Ascorbic acid399.0±10.250.0487.7±19.2108.6Dopamine 1.0 1.0±0.08100.0Uric acid10.09.9±0.699.0tryptophan40.039.0±1.197.5 Dopamine injection Ascorbic acid200.0207.7±4.9103.9Dopamine93.2±3.5 1.592.5±1.297.7Uric acid50.051.8±2.2103.6tryptophan50.051.3±1.8102.6All samples were analyzed using standard addition method(n=3).a Mean value±standard deviation(n=3).3.2%,5.6%and5.4%for AA,DA,UA and Trp of its original response after13days,respectively.The relative standard deviation(RSD) (n=10)for all these species was less than7.09%.Thus,the pro-posed electrode showed a high stability and good reproducibility and anti-interference ability.3.6.Sample analysisDopamine hydrochloride injection,vitamin C tablets,human urine and serum samples were selected for analysis using the stan-dard addition method.All samples were diluted with0.1M PBS (pH4.0)before the measurements to prevent the matrix effect of authentic samples.Then,appropriate amount of each sample was added into5mL0.1M PBS(pH4.0),respectively.To ascer-tain the correctness of the results,the samples were spiked with certain amounts of standard AA,DA,UA and Trp and then the total values were detected using DPV.The results were listed in Table2.The recovery rates of the samples ranged between95.0% and108.6%,showing that the proposed method could be effectively used for the determination of AA,DA,UA and Trp in commercial samples.4.ConclusionsIn conclusion,a novel GNPs/PImox/GCE was constructed to determine AA,DA,UA and Trp in this work.The modiﬁed elec-trode not only showed high selectivity towards the oxidation of AA, DA,UA and Trp,but also resolved their overlapped oxidation peaks into four well-deﬁned peaks,respectively.This was attributed to a decrease of the reduction potential ability of PImox,the very high electron transfer rate of GNPs that can remarkable increase in peak current towards the compounds,and the remarkable syner-gistic effects of PImox and GNPs.The simple fabrication procedure, low detection limit,high selectivity,good stability and sensitivity, suggest that this modiﬁed electrode is an attractive candidate for practical applications.AcknowledgmentsThe National Natural Science Foundation of China(21075100), the Ministry of Education of China(Project708073),the Nature Science Foundation of Chongqing City(CSTC-2009BA1003, 2011BA7003)and State Key Laboratory of Electroanalytical Chem-istry(SKIEAC2010009),China supported this work.Appendix A.Supplementary dataSupplementary data associated with this article can be found,in the online version,at /10.1016/j.aca.2012.06.045. 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物理学外文翻译

Effect of Quantum Confinement on Electrons and Phonons in Semiconductors We have studied the Gunn effect as an example of negative differential resistance(NDR).This effect is observed in semiconductors,such as GaAs,whose conduction band structure satisfies a special condition,namely,the existence of higher conduction minima separated from the band edge by about 0.2-0.4eV..As a way of achieving this condition in any semiconductor,Esaki and Tsu proposed in 1970 [9.1]the fabrication of an artificial periodic structure consisting of alternate layers of two dissimilar semiconductors with layer superlattice.They suggested that the artificial periodicity would fold the Brillouin zone into smaller Brillouin zones or “mini-zones”and therefore create higher conduction band minima with the requisite energies for Gunn oscillations.iWith the development of sophisticated growth techniques such as molecular beam epitaxy（MBE）and metal-organic chemical vapor deposition(MOCVD)discussed in Sect.1.2,it is now possible to fabricate the superlattices(to be abbreviated as SLs)envisioned by Esaki and Tsu[9.1].In fact,many other kinds of nanometer scale semiconductor structures(often abbreviated as nanostructures)have since been grown besides the SLs.A SL is only one example of a planar or two-dimensional nanostructure .Another example is the quantum well (often shortened to QW).These terms were introduced ｉｎＳｅｃｔｓ．１．２ａｎｄ７．１５ｂｕｔｈａｖｅｎｏｔｙｅｔｂｅｅｎｄｉｓｃｕｓｓｅｄｉｎｄｅｔｉａｌ．Ｔｈｅｐｒｏｐｏｓｅof this chapter is to study the electronic and vibrational properties of these two-dimensional nanostructures.Structures with even lower dimension than two have also been fabricated successfully and studied. For example,one-dimensional nanostructures are referred to as quantum wires.In the same spirit,nanometer-size crystallites are known as quantum dots.There are so many different kinds of nanostructures and ways to fabricate them that it is impossible to review them all in this introductory book. In some nanostructures strain may be introduced as a result of lattice mismatch between a substrate and its overlayer,giving rise to a so-called strained-layer superlattice.In this chapter we shall consider only the best-study nanostructures.Our purpose is to introduce readers to this fast growing field.One reason why nanostructures are of great interest is that their electronic and vibrational properties are modified as a result of their lower dimensions and symmetries.Thus nanostructures provide an excellent opportunity for applying the knowledge gained in the previous chapters to understand these new developments in the field of semiconductors physics.Due to limitations of space we shall consider in this chapter only the effects of spatial confinement on the electronic and vibrational properties of nanostructures and some related changers in their optical and transport properties.Our main emphasis will be on QWs,since at present they can be fabricated with much higher degrees of precision and perfection than all other structures.We shall start by defining the concept of quantum confinement and discuss its effect on the electrons and phonons in a crystal.This will be followed by a discussion of the interaction between confined electrons and phonons.Finally we shall conclude with a study of a device(known as a resonant tunneling device)based on confined electrons and the quantum Hall effect(QHE)in a two-dimensional electron gas.The latter phenomenon was discoveredby Klaus von Klitzing and coworkers in 1980 and its significance marked by the award of the 1985 Nobel Prize in physics to ｖｏｎ Klitzing for this discovery.Together with the fractional quantum Hall effect it is probably the most important development in semiconductor physics within the last two decades.Quantum Confinement and Density of StatesIn this book we have so far studied the properties of electrons ,phonons and excitons in either an infinite crystal or one with a periodic boundary condition(the cases of surface and interface states )In the absence of defects, these particles or excitations are described in terms of Bloch waves,which can propagate freely throughout the crystal.Suppose the crystal is finite and there are now two infinite barriers,separated by a distance L,which can reflect the Bloch waves along the z direction.These waves are then said to be spatially confined.A classical example of waves confined in one dimension by two impenetrable barriers is a vibrating string held fixed at two ends.It is well-known that the normal vibration modes of this string are standing waves whose wavelength λ takes on the discrete values given by Another classical example is a Fabry-Perot interferometer (which has been mentioned already in Set.7.2.6 in connection with Brillouin scattering).As a result of multiple reflections at the two end mirrors forming the cavity ，electromagnetic waves show maxima and minima in transmission through the interferometer at discrete wavelengths.If the space inside the cavity is filled with air,the condition for constructive interference is given by (9.1).At a transmission minimum the wave can be considered as “confined ”inside the interferometer.n λ=2L/n, n=1,2,3… .(9.1)For a free particle with effective mass *m confined in a crystal by impenetrablebarriers(i.e.,infinite potential energy)in the z direction,the allowed wavevectors z k of the Bloch waves are given byzn κ=2∏/n λ=n ∏/L, n=1,2,3… (9.2)And its ground state energy is increased by the amount E relative to the unconfined case:))(2(2222212Lm m k E z ∏==∆** (9.3)This increase in energy is referred to as the confinement energy of the particle.It is a consequence of the uncertainty principle in quantum mechanics. When the particle is confined within a distance L in space(along the z direction in this case)the uncertainty in the z component of its momentum increases by an amount of the order of /L.The corresponding increase in the particle ’s kinetic energy is then givenby(9.3).Hence this effect is known also as quantum confinement.In addition to increasing the minimum energy of the particle,confinement also causes its excited state energies to become quantized.We shall show later that for an infinite one-dimensional”square well”potential the excited state energies are given by n E∆2,where n=1,2,3…as in (9.2).It is important to make a distinction between confinement by barriers and localization via scattering with imperfections。

ni基合金中al元素和nb元素扩散速率

ni基合金中al元素和nb元素扩散速率【知识】深度解析NI基合金中Al元素和Nb元素扩散速率导语：本文将着重探讨NI基合金中Al元素和Nb元素扩散速率的相关问题，通过全面评估和分析，帮助读者深入理解这一主题。

本文将从简到繁、由浅入深地介绍，以确保读者对主题有全面、深刻和灵活的理解。

1. 背景介绍1.1 NI基合金的应用领域NI基合金是一类基于镍元素构成的合金材料，由于其优异的耐腐蚀性、高温强度、低温韧性和优良的机械性能，被广泛应用于航空航天、化工、能源等领域。

1.2 Al元素和Nb元素在NI基合金中的作用Al元素和Nb元素是NI基合金中常见的合金元素，在合金性能和微观结构调控中发挥重要作用。

Al元素可提高合金的抗腐蚀性和高温强度；而Nb元素则对合金的晶粒尺寸和相变行为产生显著影响。

2. Al元素和Nb元素扩散速率的研究进展2.1 实验方法及研究手段通过实验手段，研究人员可以定量分析Al元素和Nb元素在NI基合金中的扩散速率。

常用的实验方法包括扩散偶实验、扩散层厚度测量等。

利用电子显微镜、能谱仪等先进设备，可以对扩散过程进行详细观察和结构分析。

2.2 影响Al元素和Nb元素扩散速率因素Al元素和Nb元素在NI基合金中的扩散速率受多种因素的影响，如温度、合金成分、晶粒尺寸等。

具体而言，温度是影响扩散速率的重要因素，高温条件下扩散速率显著增加。

合金成分中的其他元素也可能对扩散速率产生影响。

3. Al元素和Nb元素扩散速率的机理探讨3.1 Al元素扩散机理关于Al元素在NI基合金中的扩散机理，学界存在不同的理论解释，其中一种观点认为，Al元素通过晶界、空隙或其他扩散通道扩散。

合金的微观结构和合金元素间的相互作用也对Al元素扩散过程具有重要影响。

3.2 Nb元素扩散机理相比于Al元素，Nb元素在NI基合金中的扩散机理研究较少。

目前，学界普遍认为，Nb元素主要通过体扩散的方式在NI基合金中传输。

然而，对于Nb元素在合金微观结构中的具体扩散路径及机理的研究仍然存在一定的争议和不确定性。

材料物理导论名词解释

Absorption coefficient 吸收常数：垂直于光束方向的水层元内单位厚度的吸收量Acceptor impurity 受主杂质：lll族杂质在Si、Ge中能够接受电子而产生导电空穴并形成负电中心acceptor ionization 受主电离：空穴挣脱受主杂质束缚的过程Antiferromagnetism 反铁磁性：材料中相邻原子或离子的磁矩作反向平行排列使得总磁矩为零的性质。

Birefringence 双折射：光入射到各向异性的晶体分解为两束光而沿不同方向折射的现象Conduction bands 导带：一部分被电子填充，另一部分能级空着的允带Crystallization 结晶：液态金属转变为固态金属形成晶体的过程Current density 电流密度：描述电路中某点电流强弱和流动方向的物理量currie temperature 居里温度：自发极化急剧消失的温度Diamagnetism 抗磁性：外加磁场使材料中电子轨道运动发生变化，感应出很小的磁矩且该磁矩与外磁场方向相反的性质Dielectric breakdown 介电体击穿：介电体在高电场下电流急剧增大，并在某一电场强度下完全丧失绝缘性能的现象dielectric loss 介电损耗：将电介质在电场作用下，单位时间内消耗的电能Dielectric medium 电介质：能够被电极化的介质Dipolar turning polarization 偶极子转向极化：极性介电体的分子偶极矩在外电场作用下，沿外施电场方向转向而产生宏观偶极矩的极化Disperse phase 分散相：被分散的物质Dispersion of refractive index 折射率的色散：材料的折射率m随入射光频率减小而减小的现象Donor impurity level 施主能级：将被施主杂质束缚的电子能量状态称施主能级Donor impurity 施主杂质：V族杂志在硅、锗中电力时，能够释放电子而产生导电导子并形成整点中心，称其位施主杂质或n型杂志donor ionization 施主电离：施主杂质释放电子的过程Electirical polarization 电子极化：电场作用下，构成原子外围的电子云相对原子核发生位移形成的极化Electrical field 电场：由电荷及变化磁场周围空间里存在的一种特殊物质Electrical resistivity 电阻率：某种材料制成的长1米、横截面积是1平方米的在常温下（20℃时）导线的电阻，叫做这种材料的电阻率。

金属离子对牛胰岛素淀粉样纤维形成的作用

金属离子对牛胰岛素淀粉样纤维形成的作用翟彩宁1，2，曾成鸣11 陕西师范大学化学与材料科学学院，西安（710062）2 陕西师范大学生命科学学院，西安（710062）E-mail：ning_1983@摘要：蛋白质或者多肽转变为淀粉样纤维主要取决于所处的环境条件。

本文采用ThT和ANS荧光、圆二色谱和偏振光显微镜等方法研究了溶液中金属离子(Mg2+, Cu2+, Zn2+, Co2+, K+, Li+和 La3+) 对牛胰岛素淀粉样纤维形成的影响，结果表明，所有金属离子对胰岛素淀粉样纤维化均有促进作用，其作用大小次序为：La3+ > M g2+> Cu2+> Zn2+ > Li+ > Co2+ > K+。

这种作用与促进蛋白质疏水区暴露的作用是一致的。

相关性分析显示，金属离子与蛋白质分子间的不同作用与其水合自由能和静电常数有关。

并进一步由此结果推测了金属离子与蛋白质的作用机理，以及蛋白质淀粉样纤维化的分子机制。

关键词：金属离子；胰岛素；淀粉样纤维化；疏水作用；相关性分析中图分类号: Q518.41 引言越来越多的研究显示，蛋白质淀粉样纤维化是很多人类疾病的重要特征。

例如，阿尔茨海默疾病、海绵状脑病和帕金森病等均与相关的蛋白质或多肽的纤维化沉积有关[1]。

进一步的研究发现，在一定的条件下，一些与疾病不相关的蛋白质也可以形成淀粉样纤维[2-3]，如胰岛素等。

所以，淀粉样纤维化是所有蛋白质的共性，与其序列和结构无关。

研究蛋白质淀粉样纤维形成的环境条件和分子机制对于探索相关疾病的病因和治疗方法具有重要的意义。

胰岛素是动物胰脏中胰岛β-细胞所分泌的一种调节糖代谢的激素，由两条富含α螺旋的短肽链（A链和B链）组成，两链之间由2个二硫键链接，A链内有一条二硫键。

人胰岛素和牛胰岛素具有高度的相似性。

目前尚未发现内源胰岛素在体内的淀粉样沉积与疾病的关系，但作为临床应用的外源胰岛素在合成及药物储存过程中产生的淀粉样沉积可能具有免疫原性，长期使用可以严重影响其治疗效能。

三元正极材料分段煅烧的原因

三元正极材料分段煅烧的原因英文回答：Multi-stage calcination is performed on ternary cathode materials for several reasons:1. Improved Phase Purity: Calcination involves heating the precursor materials at high temperatures to induce phase transitions and crystal growth. By performingmultiple calcination steps with controlled temperature profiles, the desired crystal phase can be preferentially formed while minimizing the formation of undesired phases. This enhanced phase purity is crucial for optimizing the electrochemical performance of the final material.2. Controlled Grain Growth: Calcination significantly influences the morphology and grain size of the material. By dividing the calcination process into multiple stages, the grain growth can be controlled, leading to a more homogeneous microstructure with smaller and more uniformgrains. This refined microstructure promotes fasterlithium-ion diffusion and reduces polarization, resultingin improved electrochemical properties.3. Surface Modification: Multi-stage calcination allows for surface modification of the cathode material. The introduction of specific dopants or coatings during different calcination steps can enhance the surfacestability and electronic conductivity of the material. This surface modification contributes to improved cycling stability, rate capability, and overall electrochemical performance.4. Removal of Impurities: Calcination serves as a purification process by removing volatile impurities and residual organic species from the precursor materials. Performing multiple calcination steps ensures thorough removal of these impurities, leading to a higher purity of the final cathode material and enhanced electrochemical stability.5. Oxygen Content Control: The calcination process iscritical for controlling the oxygen content in the cathode material. By adjusting the temperature and atmosphere during each calcination step, the oxygen stoichiometry can be precisely tuned to optimize the electrochemical activity and stability of the material.中文回答：三元正极材料的分段煅烧原因：1. 提高相纯度，煅烧涉及在高温下加热前驱材料以诱发相变和晶体生长。

稀土文摘快报

42稀土信息 No.2 2024RARE EARTH INFORMATION稀土配位元素对钛基烧绿石及其介电现象的影响Influence of rare earth coordinated elements in titanium-based pyrochlores and their dielectric phenomena领域：配位化学团队：捷克布拉格化学技术大学无机化学系期刊：Coordination Chemistry Reviews (impact factor:20.6) 1区稀土配位钛烧绿石是电子用无机陶瓷中重要的材料之一。

钛酸盐型烧绿石通常具有高离子电导率和低活化能。

它还具有化学稳定性、机械完整性以及与相邻电极材料的良好一致性。

稀土基烧绿石可作为主要氧离子导体应用于电解质。

这些材料在高温固体氧化物燃料电池方面具有竞争力。

有关这种独特的结构化合物，目前仅有少数综述报告。

关于具有重要电子特性的烧绿石材料的研究数据则更少。

本文还总结了稀土元素配位化学对烧绿石材料晶体结构的影响，包括介电响应。

本综述主要关注烧绿石材料引人注目的微晶结构，并重点介绍其现代化进展。

具体而言，还介绍并评估了稀土烧绿石钛酸盐的应用。

根据其未来的发展，对其前景和掺杂策略进行了介绍。

基于工程适体的重金属和稀土元素环境可持续性传感与回收研究进展Recent advances in engineering aptamer-based sensing and recovery of heavy metals and rare earth elements for environmental sustainability领域：环境工程团队：韩国忠北大学微生物学系，美国辛辛那提大学化学与环境工程系期刊：Chemical Engineering Journal (impact factor:15.1) 1区重金属（HMs）和稀土元素（REEs）被广泛应用于工业和技术领域，但当它们被释放到环境中时，也会对环境和人类健康产生有害影响。

多金属掺杂氮化碳英语表达

多金属掺杂氮化碳英语表达全文共四篇示例，供读者参考第一篇示例：Multi-metal-doped carbon nitride, a type of carbon-based material, has attracted increasing attention in recent years due to its unique properties and wide range of applications. The incorporation of multiple metals into the carbon nitride structure enhances its catalytic activity, stability, and conductivity, making it a promising material for various industrial and environmental applications.第二篇示例：英文：Title: Multimetal Doped Nitrogen-Carbon: A Versatile Material for Various ApplicationsSynthesis of MM-N-C Materials:The synthesis of MM-N-C materials involves the incorporation of multiple metals into the nitrogen-carbon matrix through various methods such as chemical vapor deposition, hydrothermal synthesis, and solvothermal synthesis. The choiceof metals and their doping levels can significantly affect the properties of MM-N-C materials, such as conductivity, catalytic activity, and mechanical strength.第三篇示例：Properties of multi-metal doped carbon nitrideThe incorporation of multiple metal dopants into carbon nitride can induce significant changes in its electronic and structural properties. Metal dopants can act as active sites for catalytic reactions by facilitating charge transfer processes and modifying the energetics of surface reactions. Additionally, the presence of metal atoms can create defects and vacancies in the CN lattice, leading to increased catalytic activity and stability. The synergistic effects between different metal dopants can further enhance the performance of multi-metal doped carbon nitride as a catalyst. For instance, the co-existence of iron and cobalt dopants in CN can promote the formation of active species for oxygen reduction reactions and improve the overall efficiency of fuel cells.第四篇示例：Multi-metal-doped carbon nitride (CNx) is a novel and promising material that has attracted significant attention inrecent years due to its unique properties and wide range of potential applications. In this article, we will discuss the synthesis, properties, and applications of multi-metal-doped CNx.。

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Journal of Alloys and Compounds 513 (2012) 573–579Contents lists available at SciVerse ScienceDirectJournal of Alloys andCompoundsj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /j a l l c omEffects of multi-element dopants of TiO 2for high performance in dye-sensitized solar cellsJi Sun Im,Jumi Yun,Sung Kyu Lee,Young-Seak Lee ∗Department of Fine Chemical Engineering and Applied Chemistry,BK21-E 2M,Chungnam National University,Daejeon 305-764,Republic of Koreaa r t i c l ei n f oArticle history:Received 6August 2011Received in revised form 29October 2011Accepted 2November 2011Available online 9 November 2011Keywords:Electrode materials SemiconductorsElectrochemical reactionsElectrochemical impedance spectroscopya b s t r a c tMulti-inorganic element-doped TiO 2was prepared as a semiconductor in the working electrode of a dye-sensitized solar cell (DSSC).The particle size of TiO 2decreased by about 20%after the use of a paint shaker that enlarged the contact area between the TiO 2and the dye or electrolyte.The ﬁll factor and efﬁciency of the DSSC improved by around 14%and more than a factor of 3,respectively,based on the effects of multi-element dopants and the size reduction of TiO 2.The mechanism was suggested by electrochemi-cal impedance spectroscopy,intensity-modulated photocurrent spectroscopy,and intensity-modulated photovoltage spectroscopy analysis methods.It seems that the doped multi-inorganic elements (B,C,N and F)prevent the electrons in the conduction band of TiO 2from returning to the dye or electrolyte for recombination by improved electron transfer.In addition,the reduced size of TiO 2was beneﬁcial for active reactions at the TiO 2/dye/electrolyte interface by enlarging the contact area.© 2011 Elsevier B.V. All rights reserved.1.IntroductionThe dye-sensitized solar cell (DSSC)has attracted attention as an alternative energy device for dealing with fossil energy depletion because it has many advantages such as low cost,a simple manu-facturing process,low environmental loads and high efﬁciency in converting solar energy into electricity [1–3].However,the indus-trialization of DSSCs suffers from insufﬁcient efﬁciency.Therefore,numerous studies to improve the efﬁciency of DSSCs have been pre-sented.They can be categorized into four types:(1)efﬁcient dyes for high sensitivity of the solar cell,(2)working electrode system development for easy charge transfer through the conduction band of the semiconductor,(3)electrolytes with efﬁcient redox couples such as iodide ions and tri-iodide ions and (4)counter electrode systems for maximized electron transport [4–6].Among these approaches,the efﬁciency of the working elec-trode system was investigated in this study because the major lack for high performance DSSC is low efﬁcient electron transfer in working electrode.In the working electrode system,the elec-trons excited in the lowest unoccupied molecule orbital (LUMO)of the dye are transferred to the conduction band (CB)of TiO 2and then travel to the FTO glass.In this process,a lot of electrons in the CB of TiO 2travel to the dye or electrolyte by trapping–detrapping events before reaching the FTO glass collecting electrode.This phe-nomenon results in the low efﬁciency of the DSSC [7–9].Therefore,∗Corresponding author.Tel.:+82428217007;fax:+82428226637.E-mail addresses:eujs3915@cnu.ac.kr ,youngslee@cnu.ac.kr (Y.-S.Lee).investigations on preventing the electron trapping effects in the CB of TiO 2have been carried out by many researchers.In this study,the inorganic element doping method was used to obtain a high efﬁciency of the DSSC by preventing the elec-tron trapping effects in the CB of TiO 2.The relation between DSSC efﬁciency and multi-element dopants was investigated based on efﬁcient electron transfer in the CB of TiO 2.In addition,the size reduction effects were observed to lead to an enlarged contact area of TiO 2with the dye or electrolyte,and these effects were further investigated.The mechanism of improved efﬁciency of DSSCs was also investigated by electrochemical analysis based on inorganic element dopants and size reduction of TiO 2.2.Materials and methods2.1.Preparation of multi-inorganic-element-doped TiO 2Commercial TiO 2(anatase,99.7%,5g,Aldrich)and tetraethylammonium tetraﬂuoroborate ((CH 3CH 2)4N +BF 4−,TEATFB,99%, 2.17g,0.01M,Mw:217g,Aldrich)were mixed with distilled water (25ml)and then stirred at room tem-perature for 48h.The resultant mixture was thermally treated at 600◦C for 1h with a 5◦C/min heating rate and a 30ml/min nitrogen gas ﬂow.The commercial TiO 2and TEATFB-doped TiO 2were termed PT (pristine titania)and DT (doped titania).A size-reduced DT sample was prepared by using paint shaking for 20min as shown in Fig.1and was termed SDT (size-reduced DT).2.2.Preparation of TiO 2pastePT,DT and SDT samples of 2g each were added to a mixture solution of PEG (poly ethylene glycol,molecular weight:30,000)solution (0.5g PEG with 7ml distilled water),ethanol (Fw:46.07,5ml)and terpienol (Fw:154.25,1.5ml).The resultant mixture was then thermally treated at 100◦C for 6h.0925-8388/$–see front matter © 2011 Elsevier B.V. All rights reserved.doi:10.1016/j.jallcom.2011.11.011574J.S.Im et al./Journal of Alloys and Compounds 513 (2012) 573–579Fig.1.Diagram of the paint shaker used in this study.2.3.Preparation of working electrodeFTO (ﬂuorine-doped tin oxide,Solaronix)was washed with 2-propanol,ethanol and distilled water several times to remove impurities and was then dried.The pre-pared TiO 2paste was loaded by the screen printing method with a V-350membrane.The TiO 2-paste-loaded FTO was dried at 70◦C for 1h and then thermally treated at 450◦C for 30min with a 1.5◦C/min heating rate under an air ﬂow of 30ml/min.The dye solution was prepared with 25ml of acetonitrile,25ml of r-butyrolactone and 70mg of dye (Ruthenium535-bis TBA,Solaronix).The prepared TiO 2-paste-loaded FTO was immersed in the prepared dye solution and then stirred at 40◦C for 24h to absorb the prepared dye in the TiO 2.The thickness of the loaded TiO 2layer was ﬁxed at 4␮m.The resultant sample was dried at room temperature overnight.2.4.Preparation of counter electrodeFTO was coated with Pt paste (Pt-1,DYESOL)using a screen printing method and then dried at 70◦C for 3h.Afterwards,it was thermally treated at 450◦C for 30min with a 1.5◦C/min heating rate under an air ﬂow of 30ml/min.The thickness of the loaded Pt layer was ﬁxed at 4␮m.2.5.Assembly of DSSCThe cell area of the counter and working electrodes was ﬁxed at 1cm ×1cm.Two holes in the counter electrode were punched for injection of the electrolyte.A surlyn ﬁlm (2cm ×2cm with a hole of 1cm ×1cm,thickness:25␮m,Solaronix)was located between the counter and working electrodes to bond the two electrodes.They were clipped for immobilization of each part and then thermally treated at 100◦C for 4min to bond the two electrodes by dissolving the surlyn ﬁlm.The elec-trolyte (AN-50,Solaronix)was injected through the holes in the counter electrode.Then,the holes were blocked by surlyn ﬁlm.The assembly procedure of the cell is presented in Fig.2.2.6.Measurement of electrochemical propertiesI –V characteristics were measured by a photocurrent–voltage (I –V )curve ana-lyzer (IVIUM Technologies,PECK2400-N,version 2.1)under AM 1.5(100mW/cm 2)irradiation using a solar simulator (Peccell Technologies,PEC-L01).Electrochemical impedance spectroscopy (EIS)measurements were carried out under open circuit with an electrochemical work station (ZAHNER,IM6ex)with a frequency range of 10mHz to 100kHz.The magnitude of the alternating signal was 5mV.Impedance measurements were carried out under a forward bias of 600mV.Intensity-modulated photocurrent spectroscopy (IMPS)under short-circuit conditions and intensity-modulated photovoltage spectroscopy (IMVS)under open-circuit conditions were performed on the DSSCs.A light emitting diode (LED,635nm)was used as the light source.The light intensity was modulated with a sine-shaped voltage supplied by a Solartron 1255B frequency responseanalyzerFig.2.Diagram for assembly of the DSSC in this study.(FRA)over the appropriate frequency range.The DC light generated by the LED,with the intensity up to 2W m −2,was used as the superimposed constant illumina-tion in the measurements.The amplitude and phase shift of the current response with respect to the modulation of the light intensity were measured with FRA.2.7.Characterization of samplesThe surface morphology of the samples was investigated by using a ﬁeld emis-sion scanning electron microscope (FE-SEM,Hitachi,S-5500).Images were taken without prior treatment (e.g.,Pt coating)to ensure the acquisition of accurate images.The average size of the clusters was measured by the software program installed on the FE-SEM apparatus.The particle size density was evaluated using a laser scattering particle size analyzer (HELOS/RODOS &SUCELL,Sympatec GmbH Co.,Germany)to investigate the size reduction effect caused by the paint shaker.The XPS spectra of used samples in this study were obtained with a MultiLab 2000spectrometer (Thermo Electron Co.,England)to evaluate the chemical species on the surface of TiO 2based on effects of multi-element doping.Al K ␣(1485.6eV)X-rays were used with a 14.9-keV anode voltage,a 4.6-A ﬁlament current and a 20-mA emission current.All samples were treated at 10−9mbar to remove impurities.The survey spectra were obtained with a 50-eV pass energy and a 0.5-eV step size.Core level spectra were obtained at 20-eV pass energy with 0.05-eV step size.3.Results3.1.Surface morphology of prepared samplesFE-SEM images of the PT,DT and SDT samples are presented in Fig.3,displaying the surface morphology.The working elec-trodes after loading three samples are presented in Fig.3(a),(c)and (e).And the morphologies of prepared three samples are in Fig.3(b),(d)and (f).The agglomeration degree of TiO 2was signif-icantly decreased via using a paint shaker as seen in Fig.3(e).The average particle size of PT,as measured by the software program installed on the FE-SEM apparatus,is about 27.2±6.2nm.The par-ticle size became slightly larger due to B,C,N and F doping effects on the surface of TiO 2.The effect of the size reduction of TiO 2is shown in the SDT sample,with an average particle size of 22.3±4.5nm.This result correlates well with the result of the particle size dis-tribution shown in Fig.4.The peak position was shifted to left side signiﬁcantly indicating the size reduction of TiO 2.Therefore,it can be concluded that the contact area of TiO 2with the dye or the electrolyte may be signiﬁcantly increased,leading to an enhanced reaction at the TiO 2/dye/electrolyte interface for high efﬁciency of the DSSC because the high contact area between semiconductorJ.S.Im et al./Journal of Alloys and Compounds 513 (2012) 573–579575Fig.3.FE-SEM images of (a and b)PT,(c and d)DT and (e and f)SDT.Particel size (nm)10080604020D e n s i t y d i s t r i b u t i o n (q 3*)0.00.51.01.52.0Fig.4.Particle size density distribution of PT,DT and SDT samples.and dye can provide more enough sites for an efﬁcient electron transfer from dye to TiO 2.3.2.Chemical analysis of B,C,N and F dopants on the surface of TiO 2The chemical bonds of B,C,N and F with TiO 2were deter-mined by XPS analysis as shown in Fig.5.Fig.5(a)shows the F 1s XPS spectrum.The main peak of the asymmetrical line shape in this spectrum can be assigned to structures containing oxyﬂuo-ride (F–Ti–O)functional groups,whereas the shoulder at 689eV is related to the F–Ti bond [10].These ﬁndings reveal that ﬂuorine is incorporated into the TiO 2by replacing oxygen atoms in its lattice,forming non-stoichiometric TiO 2–x F x structures [11].The forma-tion of these TiO 2–x F x structures,in which the ﬂuorine ions are incorporated in the TiO 2lattice,contributes to the improved TiO 2crystallinity [12].As shown in Fig.5(b),the N 1s peak at 400eV was observed in the doped TiO 2samples.Similarly,a signiﬁcant peak near 402eV and a minor peak near 400eV,assigned to the N 1s peak,have been reported in N-doped TiO 2[13].Sakthivel and Kisch [10]prepared nitrogen-doped titania from titanium tetraisopropoxide576J.S.Im et al./Journal of Alloys and Compounds 513 (2012) 573–579Bind ing ener gy (eV)682684686688690692694696I n t e n s i tyBind ing ene rgy (e V)392394396398400402404406408I n t e n s i tyBind ing ene rgy (e V)182184186188190192194196198I n t e n s i tyBinding ene rgy (eV )278280282284286288290I n t e n s i tyFig.5.XPS peaks of SDT:(a)F 1s,(b)N 1s,(c)B 1s and (d)C 1s.or titanium tetrachloride and thiourea [14].They observed a bind-ing energy of 400.1eV,assigned to hyponitrite at the surface,whichwas attributed to the doped nitrogen.Fig.5(c)shows the XPS spec-trum of the B 1s region on the surface of the SDT sample.Note that the B 1s region contains only one peak and that the binding energy shifts from 191.1eV to 191.5eV.This shift implies the formation of a weak Ti–B bond and is also attributed to the interference effects of other elements bonding with Ti.By taking into account the stan-dard binding energy of B 1s in TiB 2(187.5eV,B–Ti bond),this result indicates that the boron atom is probably incorporated with the TiO 2to some extent and that the chemical environment surround-ing the boron is similar to that of the TiB 2[15].In Fig.5(d),the peaks near 285eV are attributed to C 1s [16].In the case of C and F,there is no observable peak shift,which is due to the strong bond between the F and C atoms and the Ti particles.In the SDT sample,the elemental compositions of O,Ti,N,C,F and B were 57.6,24.5,0.9,14.2,1.5and 1.3at.%.Resultantly,TiO 2−x N x (x =0.015),TiO 2−x C x (x =0.197),TiO 2−x B x (x =0.022)and TiO 2−x F x (x =0.025)structures were obtained in this study.3.3.Photocurrent–voltage behavior of DSSCsThe photocurrent–voltage curves of the DSSCs are presented in Fig.6.The open-circuit voltage (V oc )and short-circuit current (I sc )of each sample were measured at I =0mA and V =0V.The maximum voltage (V max )and maximum current (I max )were calculated at the point of maximum power (P max ,assigned as point a,b or c in Fig.6)based on following equation [17–19]:P =I ×V(1)Furthermore,the ﬁll factor (FF)and efﬁciency (Á)are given by FF =V max ×I maxV oc ×I sc(2)Á(%)=V oc ×I sc×FF P in ×S×100(3)In Eq.(3),S and P in represent the area of the thin ﬁlm on the work-ing electrode (1cm 2)and the incident light power (100mW/cm 2),respectively.The measured factors are presented in Table 1.I sc increased by a factor greater than two based on the effects of dop-ing elements and size reduction in DT and SDT,respectively.When comparing the values of I sc and I max in each sample,I max showed a slightly smaller current,indicating a small shunt resistance (R SH )in the DSSC [20].However,the gap of V oc and V max ( V )in each sample showed a higher change ratio;the values of V /V oc of PT,DT and SDT were 29.7,22.9and 18.4%,respectively.This trend isVoltage (V)1.00.80.60.40.20.0P h o t o c u r r e n t d e n s i t y (m A /c m 2)2468101214Fig.6.I –V characteristics of the DSSC with PT,DT and SDT.J.S.Im et al./Journal of Alloys and Compounds 513 (2012) 573–579577Table 1Photovoltaic parameters of DSSC.V oc (V)I sc (mA cm −2)V max (V)I max (mA cm −2)FF (%)V a (V)Á(%)SDT 0.92512.9590.75511.69773.6730.1708.831DT 0.8979.7370.6928.36066.2360.205 5.785PT0.8655.1560.6084.73064.4820.2572.876aV :V oc −V max .attributed to a decreased series resistance (R S ),and it is beneﬁcial for the higher FF and working voltage in DSSCs [21–23].The FF also increased dramatically,from 64.5to 73.7%,based on the effects of the multi-element doping of B,C,N and F and the size reduction of the TiO 2particles.The efﬁciency of the DSSC was improved over three times,up to 8.8%.4.Discussion4.1.Suggested mechanism of improved efﬁciency of prepared DSSCsThe suggested mechanism of the DSSC is depicted based on the effects of B,C,N and F doping and the size reduction of TiO 2.In Fig.7(a),the DSSC mechanism for PT is presented.The electrons are excited by solar energy from the HOMO to the LUMO indyeFig.7.Suggested mechanism for the improved efﬁciency of the DSSC based on inor-ganic element doping and the size reduction of TiO 2with (a)PT (suggested by Grätzel [24])and (b)SDT.molecule,indicatedas .These excitedelectrons diffuse into the conduction band (CB)of TiO 2,indicated as .Then,the electrons travel through the CB of theTiO 2layer towards the FTO of the working electrode,indicated as .In this process,a large num-ber of electrons move to the LUMO of the dye or electrolyte due to electron trappingeffects.This process results in electron recombi-nation,which is indicated as .The reason is considered that the electron transfer time is a few nanoseconds from the LUMO of the dye to the CB of TiO 2,whereas the electron transfer time in the CB of TiO 2is afew milliseconds [24,25].Thus,the originalvoltage inten-sity (indicated as )drops signiﬁcantly,shown as .Eventually,the working voltage intensity is determined as [26–28].The mechanism for preventing a voltage drop is shown in Fig.7(b).The electrons moving to the dye or electrolyte can be transferred through CB of TiO 2based on effects of multi-element dopants.It is well known that each B [29],C [30],N [31]and F [32]dopant lower theCB of TiO 2resulting the steps with different energy level as shown in [33–35].These multi-energy level steps can accelerate the electron ﬂow for lower energy lever resulting in an electron path valley.When comparing with PT sample shown in Fig.7(a),it can be estimated that the long electron path way in the CB of TiO 2with same energy level is not efﬁcient for electron transfer.Even though a little voltage drop can be estimated by the lowered CB of TiO 2,it seems that the preventing effect of electron recombination is much powerful.Eventually,the enlarged electron path way can be constructed leading the efﬁcient electron transferfromdye to FTO working electrode through CB of TiO 2as shown in and .In this process,the enlarged contact area between the semiconductor and the dye or electrolyte might also improve the electron charge transfer at the interface [36,37].These electrons go to the FTOof the working electrode,resulting in enhanced volt-age intensity,which is indicatedas .Thus,an improved voltage intensity can be obtained,which is indicated as .These results are correlated with the increased V max and decreased V shown in Table 1and Fig.6.In conclusion,a drop in the voltage intensity is prevented by electron recombination and signiﬁcantly improves the efﬁciency of the DSSC.4.2.EIS of samplesThe EIS results of PT,DT and SDT are presented by Nyquist plots in Fig.8.In general,the impedance spectrum of the DSSC shows three semicircles in the frequency range of 10mHz to 100kHz.The ﬁrst semicircle is related to the charge transfer at the counter elec-trode measured in the kHz range.The second semicircle is related to the electron transport at the TiO 2/dye/electrolyte interface in the range of 1–100Hz.The third semicircle shows the Warburg diffu-sion process of I −/I 3−in the electrolyte,measured in the mHz range [38–40].These three semicircles indicate the R ct1,R ct2and R diff of an equivalent circuit,as shown in Fig.8(c).In this study,each curve showed only two semicircles.The R diff was not obvious,and it was overlapped by R ct2due to the very thin spacer used in the devices.This result also agrees with the results of another group [41].In addition,the electrolyte is not an important parameter because we used the same electrolyte in prepared DSSCs.Thus,the third semicircle was not considered in this paper.The second semicircle decreased signiﬁcantly due to the effects of the doping of B,C,N578J.S.Im et al./Journal of Alloys and Compounds 513 (2012) 573–579Fig.8.Nyquist plots of PT,DT and SDT samples measured by EIS as measured in (a)1-kHz and (b)kHz range and (c)the equivalent circuit used to represent the interface in composite solar cells.and F inorganic elements and the size reduction of TiO 2,as shown in Fig.8(a).It is notable that the electron ﬂow from the LUMO of the dye to the FTO through the CB of TiO 2became more efﬁcient,sup-porting the mechanism illustrated in Fig.7.In the case of the ﬁrst semicircle,shown in Fig.8(b),three samples showed the similar values because the preparation condition of counter electrode was same.And the R s related to the sheet resistance of the FTO did not show any signiﬁcant change because the same FTO glasses were used in all samples.Therefore,it is notable that the electron charge transfer improved at the semiconductor/dye/electrolyte interface due to the effects of B,C,N and F dopants and the size reduction of TiO 2.4.3.IMPS and IMVS of samplesIMPS and IMVS were conventional methods to investigate the electron transfer and recombination process.The response plots of IMPS and IMVS were shown in Fig.9.The electron transport time ( t )and the electron recombination time ( r )can be estimated by from the IMPS and IMVS plots by following Eqs.(4)and (5)[42,43]:t =0.5× ×f 1min(4) r =0.5××f 2min(5)where f 1minand f 2minare the characteristic frequency at the minimum of the imaginary IMPS and IMVS,respectively.In addition,the elec-tron diffusion coefﬁcient (D n )and the electron diffusion length (L n )can be determined on the basis of ﬁlm thickness (d ,4␮m in this study), t and r by following Eqs.(6)and (7)[42–44]:D n =d 22.35× t(6)L n =(D n × r )0.5(7)The calculated results are presented in Table 2.It was conﬁrmedthat electron was transported more quickly through TiO 2working electrode and electron recombination was retarded signiﬁcantly.Z'20x10340x10360x 10380x 103100x103120x 103-Z "-60x103-50x103-40x103-30x103-20x103-10x1030(a)Z'500x1031x1062x1062x1063x1063x106-Z "-2.5x106-2.0x106-1.5x106-1.0x106-500.0x1030.0(b)Fig.9.IMPS (a)and IMVS (b)of samples.J.S.Im et al./Journal of Alloys and Compounds513 (2012) 573–579579 Table2IMVS and IMPS parameters.PT DT SDTf1 min (Hz)178628313177f2 min (Hz) 5.639 4.479 3.992t(s)8.9×10−5 5.6×10−5 5.1×10−5 r(s) 2.8×10−2 3.6×10−2 4.0×10−2 D n(cm2/s)0.7×10−3 1.2×10−3 1.4×10−3 L n(␮m)46.465.673.6 Accordingly,L n increased about1.6times and D n improved about 2-folds when comparing PT and SDT samples based on effects of multi-element doping and size reduction of TiO2.These results surely support the suggested mechanism explained in Section4.1 as an evidence.5.ConclusionsB,C,N and F doped TiO2was prepared as a semiconductor in the working electrode of a DSSC.Theﬁll factor and efﬁciency of the DSSC improved by around14%and by more than a factor of 3,respectively,based on the effects of multi-element dopants and the size reduction of TiO2.The mechanism for the high efﬁciency of the DSSC was suggested by EIS analysis.The B,C,N and F dopants seem to prevent the electrons in the CB of TiO2from returning to the dye or electrolyte for recombination due to the efﬁcient elec-tron transfer in TiO2working electrode.In addition,the size of TiO2was reduced by using a paint shaker,which was beneﬁcial for active reactions at the 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