First principles study on electronic structure and optical properties of novel Na-hP4 high pres

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Ni,_Cu,_Zn掺杂四方相PbTiO3力学性能、电子结构与光学性质的第一性原理研究

第53卷第2期2024年2月人㊀工㊀晶㊀体㊀学㊀报JOURNAL OF SYNTHETIC CRYSTALSVol.53㊀No.2February,2024Ni,Cu,Zn掺杂四方相PbTiO3力学性能㊁电子结构与光学性质的第一性原理研究王云杰1,2,张志远1,2,文杜林1,2,吴侦成1,2,苏㊀欣1,2(1.伊犁师范大学物理科学与技术学院,伊宁㊀835000;2.伊犁师范大学新疆凝聚态相变与微结构实验室,伊宁㊀835000)摘要:采用第一性原理研究了四方相钙钛矿PbTiO3以及Ni㊁Cu㊁Zn掺杂PbTiO3的力学性能㊁电子结构和光学性质㊂力学性能计算结果表明,Ni掺杂PbTiO3的体积模量㊁剪切模量及弹性模量在三种掺杂体系中最大㊂Ni掺杂体系德拜温度最高㊂G/B为材料的脆㊁韧性判据,Zn掺杂PbTiO3的G/B值最大,说明化学键定向性最高㊂Ni㊁Zn掺杂体系的G/B 范围为0.56<G/B<1.75,均为脆性材料,而本征PbTiO3和Cu掺杂体系G/B值小于0.56,均为韧性材料㊂通过电子结构分析,发现掺杂体系相比于本征体系带隙变窄,跃迁能量减小㊂Ni掺入使得PbTiO3费米能级处出现杂质能级,而Cu㊁Zn掺杂PbTiO3价带顶上移,费米能级进入价带,使得Cu㊁Zn掺杂PbTiO3呈现p型导电特性㊂从复介电函数㊁光学反射谱和吸收谱分析中发现,掺杂体系的静介电常数相较于本征体系有所提升㊂Ni㊁Cu㊁Zn的掺杂使得PbTiO3吸收范围扩展到红外波段,且增强了可见光波段的吸收强度,Cu掺杂PbTiO3材料的光催化特性在本征PbTiO3和三种单掺PbTiO3材料中是最好的㊂关键词:第一性原理;PbTiO3;掺杂;力学性能;电子结构;光学特性中图分类号:O561㊀㊀文献标志码:A㊀㊀文章编号:1000-985X(2024)02-0258-09 First Principles Study on Mechanical Properties,Electronic Structure and Optical Properties of Ni,Cu,Zn Doped Tetragonal PbTiO3WANG Yunjie1,2,ZHANG Zhiyuan1,2,WEN Dulin1,2,WU Zhencheng1,2,SU Xin1,2(1.School of Physical Science and Technology,Yili Normal University,Yining835000,China;2.Xinjiang Laboratory of Phase Transitions and Microstructures of Condensed Matter Physics,Yili Normal University,Yining835000,China) Abstract:The mechanical property,electronic structure,and optical properties of tetragonal perovskite PbTiO3and Ni,Cu, Zn-doped PbTiO3were studied by first principles.The mechanical property calculations show that Ni-doped PbTiO3exhibits the highest values for volume modulus,shear modulus,and elastic modulus among the three doping systems.Notably,the Ni-doped system also has the highest Debye temperature.The G/B ratio represents the material s brittleness and toughness, which is highest for Zn-doped PbTiO3,indicating the highest degree of chemical bond orientation.The G/B range for Ni and Zn-doped systems is0.56<G/B<1.75,indicating brittle materials,while the intrinsic PbTiO3and Cu-doped systems have G/B values less than0.56,indicating ductile materials.The electronic structure reveals that the doped systems have narrower band gaps and reduced transition energies compared to the intrinsic system.The introduction of Ni introduces impurity levels at the Fermi energy level in PbTiO3,while Cu and Zn doping shifts the valence band maximum upwards,causing the Fermi level to enter the valence band and resulting in p-type conductivity for Cu and Zn-doped PbTiO3.The doping of Ni,Cu and Zn expands the absorption range of PbTiO3to the infrared region and enhances the absorption intensity in the visible light range.Among the intrinsic PbTiO3and three single-doped PbTiO3materials,Cu-doped PbTiO3exhibits the best photocatalytic properties.Key words:first principle;PbTiO3;doping;mechanical property;electronic structure;optical property㊀㊀收稿日期:2023-08-02㊀㊀基金项目:伊犁师范大学科研专项提升重点项目(22XKZZ21);伊犁师范大学科研项目(2022YSZD004);伊犁师范大学大学生创新训练项目(S202110764006,YS2022G018);新疆伊犁科技计划(YZ2022Y002);新疆维吾尔自治区天山英才计划第三期(2021-2023)㊀㊀作者简介:王云杰(1999 ),男,新疆维吾尔自治区人,硕士研究生㊂E-mail:1575469121@㊀㊀通信作者:苏㊀欣,博士,副教授㊂E-mail:suxin_phy@㊀第2期王云杰等:Ni,Cu,Zn掺杂四方相PbTiO3力学性能㊁电子结构与光学性质的第一性原理研究259㊀0㊀引㊀㊀言PbTiO3(PTO)作为一种典型的钙钛矿型铁电氧化物,在居里温度(763K)以下为四方相,当处于居里温度(763K)以上时,PTO的相由四方相转变为立方相[1-2]㊂四方相PTO铁电性能较为优异,广泛应用于存储器㊁电换能器㊁微电子㊁无线通信用电介质等设备㊂此外,四方相PTO还具有较大的电光系数和较高的光折变灵敏度[3-5],因此可以用于光学传感器㊁光转换器和光调制器等[6-9]㊂除TiO2催化剂外,Ti基钙钛矿(例如CaTiO3㊁SrTiO3)还参与了自然污染物的光催化脱色和光催化水分解制氢㊂与TiO2一样,这些钙钛矿型催化剂也受到宽禁带的限制,这使得其可见光反应非常困难,光催化能力被减弱[10]㊂钙钛矿晶体结构提供了一个极好的框架,可根据特定光催化反应的要求修改带隙值,以允许可见光吸收和带边能量㊂此外,钙钛矿晶体化合物中的晶格畸变强烈影响光生载流子的分配㊂PTO由于高光催化活性,受到了广泛关注[11]㊂PTO是典型的钙钛矿型铁电氧化物,通常用于电子器件,很少用作光催化剂[12-13]㊂近年来,研究人员发现通过合理的合成方法和材料改性对PTO光催化性能进行改善㊂Hussin等和Niu 等[14-15]基于第一性原理,分别研究了La和N掺杂体系PTO的电子结构,发现La掺杂体系的带隙比本征带隙窄,N掺杂体系的PTO的费米能级进入价带顶部,使得N掺杂体系材料呈现出p型导电特性,能带结构的禁带宽度减小,对于光催化能力有一定的改善,但是关于光学性质方面并没有进行报道㊂李宏光等[16]基于第一性原理,研究了N掺杂体系的光学性质,发现光学吸收能力在可见光区域并没有较大的改善,并且Ti的氧化物进行非金属掺杂时,需要高温处理[17-18],从能量消耗的角度来说是不利的㊂综上所述,确定掺杂位置以及掺杂量成为改善PTO光催化性能的关键㊂而二价金属Ni㊁Cu㊁Zn离子更容易取代Ti4+,使O的电负性变弱,更容易改善PTO性能[19]㊂在文献调研中发现关于PTO力学性能的系统报道大多是基于本征体系[20-22],对掺杂体系的力学性能报道是罕见的,因此有必要对掺杂体系PTO光催化性能研究的同时,也对掺杂体系力学性能的改善进行系统地讨论㊂本文的主要内容是采用密度泛函理论对本征以及单掺Ni㊁Cu㊁Zn四方相PTO(PTOʒNi㊁PTOʒCu㊁PTOʒZn)的力学性能和光电性能展开系统地讨论,以期PTO能够在力学性能以及光催化方面得到更大的改善㊂1㊀理论模型与计算方法四方相PTO晶体是典型的钙钛矿结构,属于P4mm空间群[23],建立共包含40个原子的2ˑ2ˑ2超胞结构,掺杂浓度为12.5%的掺杂体系结构如图1所示,考虑到边界条件的影响,用一个Ni㊁Cu㊁Zn分别去取代超胞中的Ti原子,在超胞中有8个Ti原子的位点,根据晶体的对称性所示这8个位点为等效位点,所以不同的掺杂位置对体系没有影响㊂基于密度泛函理论的第一性原理平面波赝势方法[24-25]应用MaterialsStudio8.0[26]计算了原子各轨域的电子态密度,选择基组为广义梯度近似(general gradient approximate,GGA)下的PBE(Perdew-Burke-Ernzerhof)[27-28]交换-关联泛函,使用超软赝势(ultra-soft pseudopotential,USP)计算本征以及掺杂体系PTO 的力学性能㊁电子结构和光学性质㊂将能量㊁自洽场以及能带的收敛精度均定为5ˑ10-6eV/atom;作用于原子上的最大力为0.01eV/Å,内应力收敛精度为0.02GPa,最大位移收敛精度为5ˑ10-5Å㊂截止能为400eV,在布里渊区积分采用4ˑ4ˑ4的Monkhost-Pack型K点网格进行迭代设置[29]㊂图1㊀超晶胞掺杂模型Fig.1㊀Supercell doping model260㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第53卷2㊀结果与讨论2.1㊀几何结构分析表1为几何结构优化后的本征以及掺杂体系PTO超胞的晶格常数和体积的变化㊂由表1可知,本征PTO的晶格常数计算值为a=b=7.688Å,c=9.567Å,理论值为a=b=7.759Å,c=8.572Å[30],两项数据对比,晶格常数c相差约1Å,但是理论值和计算值的c/a近似,说明选用参数的可靠性㊂与本征PTO相比, Ni㊁Cu掺杂PTO的晶格常数a㊁b㊁c减小,晶胞体积减小㊂Zn掺杂PTO的晶格常数a㊁b减小,c增大,晶胞体积增大㊂表1㊀Ni㊁Cu㊁Zn掺杂的PTO超胞晶格常数㊁密度和体积Table1㊀Lattice constants,density and volume of PTO supercell doped with Ni,Cu and Zn Sample a=b/Åc/ÅVolume/Å3Density/(g㊃cm-3)c/a PTO(Experimental)7.7598.572516.0537.802 1.1 PTO(Calculated)7.6889.567565.3527.122 1.2Ni doping7.6759.396553.4507.307 1.2Cu doping7.6559.515557.6037.268 1.2Zn doping7.6639.688568.9617.127 1.22.2㊀缺陷形成能分析缺陷形成能是表征掺杂体系稳定性和原子掺入体系难易程度的物理变量㊂基于几何结构优化后的体系总能量和不同原子的化学势计算相应结构的形成能㊂各掺杂体系的形成能E f满足以下公式[31-32]:E f=E doped-E perfect-lμX+nμTi(1)式中:E doped表示各掺杂体系的总能量,E perfect表示纯PbTiO3超晶胞体系总能量,系数l㊁n分别表示掺入的原子和替代的原子数,μX表示掺入原子(X=Ni㊁Cu㊁Zn)的化学势,μTi表示被替换的Ti原子化学势㊂由于材料的缺陷形成能与其生长制备的条件有密切关系,本文计算了富氧且富铅状态下各掺杂体系的形成能㊂从表2可以看出,Ni㊁Cu㊁Zn单掺PbTiO3体系在富O(O-rich)和富Pb(Pb-rich)条件下的形成能均为负㊂这意味着在O-rich和Pb-rich条件下,Ni㊁Cu㊁Zn原子可以融入PTO中,可在实验中制造Ni㊁Cu㊁Zn单掺PbTiO3材料㊂表2㊀Ni㊁Cu㊁Zn掺杂的PTO的缺陷形成能Table2㊀Defect formation energy of PTO doped with Ni,Cu and ZnSubstitute form O-rich and Pb-rich defect formation energy/eVNi doping-14.905Cu doping-13.336Zn doping-18.6542.3㊀力学性能基于密度泛函理论,结合当前应用最普遍的有限应变方法[33],通过计算应力应变的线性得到弹性系数6个独立分量,得到6ˑ6的弹性张量矩阵㊂根据晶格点阵的空间对称性,部分分量相等,部分分量为零㊂计算所得本征以及掺杂体系PTO晶格常数变化结构的特征弹性系数矩阵元,在优化晶体结构的基础上计算出本征以及掺杂体系PTO的弹性常数C ij,如表3所示㊂同时,基于Voigt-Reuss-Hill近似[34-36]得到体积模量㊁剪切模量㊁弹性模量㊁泊松比㊁Pugh比㊁维氏硬度㊁德拜温度θD,如表4所示㊂本文B和G取Hill值,通过弹性常数分别计算下限值B V㊁G V和上限值B R㊁G R,然后求平均值得出㊂这里弹性模量可由下面公式给出[37]B=(B V+B R)/2(2)G=(G V+G R)/2(3)其中,G V=(1/15)[C11+C22+C33+3(C44+C55+C66)-2(C12+C13+C23)],B R=Δ[C11(C22+C33+C23)+C22(C33-2C13)-C33C12+C12(2C23-C12)+C13(2C12-C13)+C23(2C13-C23)]-1,㊀第2期王云杰等:Ni,Cu,Zn掺杂四方相PbTiO3力学性能㊁电子结构与光学性质的第一性原理研究261㊀G R=15{4[C11(C22+C33+C23)+C22(C33+C13)+C33C12-C12(C12+C23)-C13(C12+C13)-C23(C13+ C23)]/Δ+3[(1/C44)+(1/C55)+(1/C66)]-1,Δ=C13(C12C23-C13C22)+C23(C12C13-C11C23)+C33(C11C22-C12C12)㊂弹性模量E和泊松比分别依照下列公式(4)和(5)计算得出E=9BG/(3B+G)(4)μ=(3B-E)/(6B)(5)采用Chen-Niu模型[38],得到维氏硬度H V公式为H V=2(k2G)0.585-3(6)其中Pugh比[39]k=G/B㊂对于本征以及掺杂体系PTO的弹性常数满足Born弹性稳定性判据[30]:C11(C22+C33)ȡ2C212,C22ȡC23, C44ȡ0,C55ȡ0,说明这四种结构是力学稳定的㊂体积模量是衡量材料是否容易被压缩的标志,Ni掺杂PTO 体积模量(80.034GPa)最大,所以相较于其他三种结构更不容易被压缩㊂剪切模量可以衡量材料硬度,Ni 掺杂PTO具有最大的剪切模量,对应最大的维氏硬度10.411GPa㊂弹性模量是标志材料刚度的重要物理量,Ni掺杂PTO的弹性模量最大,所以相较于其他三种结构刚性最高㊂G/B=1.75是区分脆性材料和延展性材料分界点,G/B=0.56是区分材料韧性/脆性分界点㊂由表4可以看出,G/B的值都小于1.75,Ni㊁Zn掺杂PTO大于0.56,都是脆性材料,本征以及Cu掺杂PTO小于0.56,属于是韧性材料㊂而泊松比反映了材料在形变下体积所发生的变化,说明四种结构形变时体积变化不大,泊松比的变化规律与Pugh比的正好相反㊂众所周知,德拜温度与材料的很多物理性质,如熔点㊁弹性㊁硬度㊁比热等基本物理量密切相关㊂采用以下公式[33]求得德拜温度θD=h kB34πV a[]1/3v m(7)式中:h为普朗克常量,k B为玻尔兹曼常量,V a为原子体积,v m为平均声速,由下式求出v m=132v3t +1v31()[]-1/3(8)式中:v1与v t分别为纵波㊁横波速度,可由下面的公式求得v1=3B+4G3ρ()1/2(9)v t=Gρ()1/2(10)式(9)和(10)中,ρ为密度,已由表1给出㊂本征以及掺杂体系PTO德拜温度的计算结果见表4㊂从表4给出的结果可以看出,Ni掺杂体系的德拜温度(201.506K)最高,与它有最大的C11(196.541GPa)㊁C23(63.626GPa)㊁C66(82.707GPa),最大的体积模量(80.034GPa),最大的剪切模量(45.499GPa)和最大的弹性模量(114.752GPa)密切相关㊂由表4可知,掺杂体系的剪切模量㊁弹性模量㊁Pugh比㊁维氏硬度和德拜温度均大于本征体系㊂其中Ni 掺杂体系的体积模量要大于本征体系,Cu㊁Zn掺杂体系的小于掺杂体系,说明除Cu㊁Zn掺杂体系在抗压性低于本征体系外,在硬度和刚性等力学性能均强于本征体系㊂可见二价金属Ni㊁Cu㊁Zn的掺杂,有助于改善四方相PTO的力学性能㊂表3㊀本征以及掺杂体系PTO的弹性常数C ijTable3㊀Elastic constants C ij of PTO in intrinsic and doped systemsCompound C11/GPa C12/GPa C13/GPa C22/GPa C23/GPa C33/GPa C44/GPa C55/GPa C66/GPa PTO172.44690.23880.526217.93161.95560.58151.59247.50381.781 Ni doping196.54190.00955.858210.65263.62661.79045.25745.19982.707 Cu doping183.37769.41847.886189.35455.26166.79630.10341.91071.456 Zn doping163.76165.71541.457163.76141.45766.02635.17035.17064.722262㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第53卷表4㊀本征以及掺杂体系PTO的体积模量(B)㊁剪切模量(G)㊁弹性模量(E)㊁泊松比(μ)㊁Pugh比(G/B)㊁维氏硬度(H V)和德拜温度θDTable4㊀Bulk modulus(B),shear modulus(G),elastic modulus(E),Poisson ratio(μ),Pugh ratio(G/B), Vickers hardness(H V),Debye temperature(θD)of PTO in intrinsic and doped systems Compound B/GPa G/GPa E/GPaμG/B H V/GPaθD/K PTO78.43539.170100.7400.2860.4998.389188.293 Ni doping80.03445.499114.7520.2610.56810.411201.506 Cu doping75.25140.052101.7410.2750.5328.977189.392 Zn doping68.30740.606101.6710.2520.5949.880190.852 2.4㊀能带结构分析图2是本征PbTiO3以及掺杂体系的能带结构图㊂为便于分析,范围选取-5~5eV,包含费米能级,在四种体系中除Ni掺杂PbTiO3为间接带隙外,其他均为直接带隙㊂图2(a)是本征PbTiO3的能带结构图,禁带宽度为2.007eV,与实验值3.6eV相较偏低[40],所以采用剪刀算符[41]修正其带隙值(剪刀算符为1.6eV),修正后的带隙为3.607eV㊂图2(b)~(d)分别是Ni㊁Cu㊁Zn掺杂PTO的能带结构图,掺杂体系的跃迁形式所需的能量,相较于本征结构降低,并且区间处于0~1eV能带条数增多,Cu㊁Zn掺杂PbTiO3带隙值分别为1.930㊁1.936eV,价带顶有所上移,费米能级进入价带顶,使得Cu㊁Zn掺杂PbTiO3呈现出p型导电特性㊂Ni 掺杂PbTiO3价带顶到导带底的间距是1.678eV,在2eV附近出现受主能级,价带顶处出现多余的空穴载流子,这有利于电子吸收极少的能量由价带顶跃迁至受主能级,再由受主能级跃迁至导带底,或者实现受主能级之间的跃迁,从而能够大幅改善PbTiO3材料的光催化特性和导电性㊂李宏光等[16]关于N掺杂PbTiO3的研究中,能带结构出现受主能级,且价带顶下移,出现p型半导体特性,但是电子跃迁性能并不比Ni㊁Cu㊁Zn 掺杂PbTiO3更强㊂图2㊀本征PTO及三种掺杂体系的能带结构分布Fig.2㊀Band structures of intrinsic PTO and three doping systems2.5㊀态密度分析图3是本征PTO以及三种掺杂体系的总态密度图和分波态密度图㊂图3(a)是本征PTO的态密度图,㊀第2期王云杰等:Ni,Cu,Zn掺杂四方相PbTiO3力学性能㊁电子结构与光学性质的第一性原理研究263㊀Ti-3d轨道是构成导带部分的总态密度主要部分㊂价带能量处于-19~-14eV的总态密度主要由Pb-5d和O-2s轨道提供,在-8eV至费米能级的总态密度主要由O-2p以及Pb-6s轨道贡献,这与相关研究结果一致[16]㊂图3(b)~(d)分别是Ni㊁Cu㊁Zn掺杂PTO的态密度图㊂掺杂体系Pb㊁Ti和O对总态密度的贡献基本与本征态一致㊂区别在于在费米面附近,主要由O-2p及Ni㊁Cu㊁Zn的3d态之间进行杂化贡献,表现出强大的局域性㊂当Ni㊁Cu㊁Zn掺杂到PTO之后,由于掺入的Ni㊁Cu㊁Zn对总态密度贡献相对较小而不易被观察,但可以从O-2p轨道的变化进行说明,使得O-2p轨道在费米能级附近出现自由电子㊂2价金属Ni㊁Cu㊁Zn 的掺杂使得Pb㊁Ti和O之间的杂化发生变化,进而影响态密度的整体分布情况㊂掺杂体系的电子从价带顶跃迁到导带底的过程变得容易,与能带结构情况吻合㊂图3㊀本征PTO及三种掺杂体系的态密度曲线Fig.3㊀Density of states curves of intrinsic PTO and three doping systems2.6㊀光学性质分析本征以及三种掺杂体系的PTO复介电函数实部曲线和虚部曲线如图4所示,图4(a)中PTO㊁PTOʒNi㊁PTOʒCu和PTOʒZn的静态介电常数分别为2.307㊁3.305㊁3.411和4.513㊂PTOʒCu在低能区介电函数实部随着光子能量的增大而增大,并到达峰值5.714(光子能量为1.38eV),从态密度图看出这是由Cu-3d轨道向O-2p轨道的电子跃迁引起的㊂图4(b)显示PTOʒNi㊁PTOʒCu和PTOʒZn的介电函数虚部主要集中在0~10eV 的低能区,而本征PTO在虚部低能区(ɤ3eV)虚部值很小,接近零,而Ni㊁Cu㊁Zn掺杂PTO体系在虚部1.5eV左右形成新的次级主峰,PTOʒCu在低于2eV的低能区具有压倒性数值㊂可见,Ni㊁Cu㊁Zn掺杂PTO 体系光谱吸收范围扩展到红外区域,且PTOʒCu更具有优势,在可见光波段的能量吸收效果较强,说明PTOʒCu在低能区的吸收效果在三种掺杂体系中是最强的㊂图4(c)是本征以及三种掺杂体系的PTO体系的反射光谱㊂可知,本征PTO在5.77㊁7.41㊁9.74eV出现三个峰值㊂Ni㊁Cu掺杂PTO体系在可见光区域能量值大于本征PTO㊂在红外光区,Ni㊁Cu㊁Zn掺杂PTO的反射值大于本征PTO体系,PTOʒCu对可见光区域和红外光区的利用率较高,这与复介电函数图所得的结果一致㊂图4(d)是含Ni㊁Cu㊁Zn掺杂的PTO的吸收光谱㊂本征PTO只吸收紫外波段,对红外部分不吸收,本征264㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第53卷PTO的禁带宽度决定了Ni㊁Cu㊁Zn掺杂的PTO体系吸收主要集中在紫外波段㊂同时,掺杂使得电子跃迁变得容易,Ni㊁Cu㊁Zn掺杂的PTO体系吸收范围扩展到红外波段㊂在可见光波段,PTOʒCu吸收效果最好,并且吸收边640nm所对应的频率为1.94eV,这表明电子是从价带内跃迁到导带的,说明PTOʒCu具有潜在的光催化能力㊂在红外以及远红外波段,PTOʒZn吸收效果和PTOʒCu相近,并且比李宏光等[16]报道的N掺杂的PTO在红外远红外区域吸收效果更好㊂吸收光谱与介电㊁反射光谱的变化趋势是一致的㊂图4㊀本征PTO及三种掺杂体系的光学图谱㊂(a)复介电函数实部;(b)复介电函数虚部;(c)反射光谱;(d)吸收光谱Fig.4㊀Optical spectra of intrinsic PTO and three doping systems.(a)Real part of complex dielectric function;(b)imaginary part of complex dielectric function;(c)reflection spectra;(d)absorption spectra3㊀结㊀㊀论1)Ni掺杂PTO的体积㊁剪切和弹性模量最大,这是Ni掺杂PTO德拜温度最高的重要原因㊂体积模量的大小是衡量材料是否容易被压缩的标志,体积模量越高,材料越不容易被压缩;高剪切模量是高硬度的基本条件,最大的剪切模量使得Ni掺杂PTO有最大的维氏硬度;弹性模量是标志材料刚度的重要物理量,表明四种材料中Ni掺杂PTO的刚性最高㊂2)Zn掺杂PTO的G/B值是四种材料中最大的,说明此结构中原子间的化学键的定向性最高㊂3)Ni㊁Zn掺杂PTO的G/B大于0.56,都是脆性材料,本征以及Cu掺杂PTO的G/B小于0.56,是韧性材料㊂泊松比反映了材料在形变下体积的变化,本征以及掺杂体系的泊松比都在0.25~0.5,表明本征及掺杂体系PTO形变时体积将不会发生较大的变化㊂4)掺杂体系较于本征体系跃迁能量减小,Ni掺入PTO材料的费米能级处出现杂质能级㊂Cu㊁Zn掺杂的PTO费米能级进入价带顶,使得Cu㊁Zn掺杂PTO材料呈现出p型导电特性㊂5)Ni㊁Cu㊁Zn的掺杂使得PTO吸收范围扩展到红外波段,且增强了可见光波段的吸收强度,四种结构中PTOʒCu材料的光催化性能最好㊂参考文献[1]㊀ZHANG S J,LI F,JIANG X N,et al.Advantages and challenges of relaxor-PbTiO3ferroelectric crystals for electroacoustic transducers:a review[J].㊀第2期王云杰等:Ni,Cu,Zn掺杂四方相PbTiO3力学性能㊁电子结构与光学性质的第一性原理研究265㊀Progress in Materials Science,2015,68:1-66.[2]㊀LIU Y,NI L H,REN Z H,et al.First-principles study of structural stability and elastic property of pre-perovskite PbTiO3[J].Chinese PhysicsB,2012,21(1):016201.[3]㊀SUNTIVICH J,GASTEIGER H A,YABUUCHI N,et al.Design principles for oxygen-reduction 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CoxBy合金力学性能、热学性质及电子性质的第一性原理研究

第 4 期第 192-199 页材料工程Vol.52Apr. 2024Journal of Materials EngineeringNo.4pp.192-199第 52 卷2024 年 4 月Co x B y 合金力学性能、热学性质及电子性质的第一性原理研究Mechanical ，thermal and electronic properties of Co x B y alloys ：a first -principles study金格1，吴尉1，李姗玲1，陈璐1，史俊勤1，2*，贺一轩1，2*，范晓丽1，2（1 西北工业大学材料学院先进润滑与密封材料研究中心，西安 710049；2 凝固技术国家重点实验室，西安 710072）JIN Ge 1，WU Wei 1，LI Shanling 1，CHEN Lu 1，SHI Junqin 1，2*，HE Yixuan 1，2*，FAN Xiaoli 1，2（1 Center of Advanced Lubrication and Seal Materials ，School of Materials Science and Engineering ，Northwestern PolytechnicalUniversity ，Xi ’an 710049，China ；2 State Key Laboratoryof Solidification Processing ，Xi ’an 710072，China ）摘要：Co x B y 合金是一种具有高硬度和高熔点的材料，因其稳定的化学性质、高强度以及良好的热稳定性，在诸多领域具有广泛的应用前景。

基于第一性原理方法研究了CoB ，Co 2B ，Co 3B ，Co 23B 6，Co 5B 16 5种Co x B y 合金的热力学性质和电子性质。

采用能量-应变方法计算了二元合金的弹性常数和相关力学特性，基于准简谐德拜模型计算了有限温度内的德拜温度ΘD 和热膨胀系数α等热力学特性。

毕业设计(论文)-基于密度泛函理论(DFT)的第一性原理计算

摘要本文主要利用基于密度泛函理论（DFT）的第一性原理计算，理论上预言了高压下LaN的压致结构相变和电子结构的压力效应。

计算结果显示LaN在高压下从NaCl结构(B1，空间群Fm3m)转变成CsCl结构(B2，空间群Pm3m)，并得到了结构转变压力，以及相应能带结构和带隙宽度的影响。

关键词：第一性原理；高压；结构相变；NaCl结构；CsCl结构AbstractThis paper mainly based on the density functional theory ( DFT ) first principles calculation, theoretically predicted LaN under high pressure pressure induced structure transformation and the electronic structure of the pressure effect. The calculation results show the LaN under high pressure from the NaCl structure ( B1, space group Fm3m ) into the CsCl structure ( B2, space group Pm3m ), and obtains the structure change of pressure, and the corresponding energy band structure and band gap width effect.Keywords:First principles; high pressure; structural transformation; NaCl structure; CsCl structure目录摘要 (I)Abstract (II)1绪论 (4)1.1晶体结构的研究进展和应用前景 (4)1.2高压研究的意义 (5)1.3本文的主要内容 (6)2正文 (7)2.1高压下晶体结构的研究现状 (7)2.2理论方法 (8)2.2.1密度泛函理论基本概念 (9)2.2.2交换关联项的处理 (11)2.2.3密度泛函理论的数值计算方法 (12)2.2.4状态密度在Brillouin zone的表示 (14)2.3高压下LaN结构相变的第一性原理计算 (14)2.3.1研究了LaN的结构 (14)2.3.2计算了两种结构的晶胞总能与体积的关系曲线 (16)2.3.3计算了LaN的相变压力 (16)2.3.4计算了LaN的能带结构和态密度 (17)结论........................................................................................................... 错误!未定义书签。

第一性原理对 Ga n N n ( n = 2~ 5) 小团簇的结构

第25卷第1期原子与分子物理学报Vo l.25 N o.1 2008年2月JOU RNA L OF A T OM IC AN D M OLECUL AR PHYSICS Feb.2008文章编号:1000 0364(2008)01 0143 06第一性原理对Ga n N n(n=2~5)小团簇的结构及电子性质的研究葛桂贤1,雷雪玲2,闫玉丽3,杨致3,赵文杰3,王清林3,罗有华3,4(1.石河子大学师范学院物理系生态物理重点实验室,新疆832003;2.新疆师范大学数理信息学院,乌鲁木齐830053;3.河南大学物理与信息光电子学院理论物理研究所,开封475004;4.华东理工大学理学院,上海200237)摘要:利用密度泛函理论的B3LY P方法在6 31G*的水平上对Ga n N n(n=2~5)团簇的结构进行优化,得到了Ga n N n(n=2~5)团簇的最稳定结构.并对最稳定结构的电子性质、成键特性和极化率进行分析.结果表明,团簇的最稳定结构为平面结构,且存在着N2和N3单元,说明N-N键在团簇的形成过程中起着决定性的作用;能隙间隔为1.776~3.563eV,表明Ga n N n(n=2~5)团簇已具有了半导体的性质.关键词:G a n N n团簇;最低能量结构;电子性质中图分类号:O641 文献标识码:AFirst principles study on structure and electronic propertiesof small Ga n N n(n=2~5)clustersGE Gui Xian1,LEI Xue Ling2,YAN Yu Li3,YANG Zhi3,ZHAO Wen Jie3WANG Q ing Lin3,LUO You Hua3,4(1.Key Laboratory of E cophysics and Department of Physics,Normal College,Shihezi University,Xinjiang832003,China;2.School of M aths Physics an d Information Sci ences,Xinjiang Normal Universi ty,U rumqi830053,China;3.Institute of T heoreti cal Physics,School of Physics and Information Optoelectronics,Henan University,Kaifeng475004,China;4.S chool of S cience,East C hi na Un i versity of Science and T echnology,Shanghai200237,China)Abstract:Geometric structure and relative stability of Ga n N n(n=2~5)clusters are studied by using the hy brid functional theory(B3LYP)w ith6 31G*basis sets.For the most stable isomers of Ga n N n(n=2~5) clusters,the electronic properties,bond properties,polarizability are analyzed.T he calculated results show that the optimized Ga n N n(n=2~5)clusters are planar structure.The most stable structures indicate a pref erence for an N2subunit or N3subunit,denoting that N N bonds play a crucial role in stabilizing the cluster. T he energy gaps are from1.776to3.563eV,revealing that these cluster may present semiconductor like properties.Key words:Ga n N n(n=2~5)clusters,the lowest energy structure,electronic properties收稿日期:2006 09 01作者简介:葛桂贤(1977-),女,讲师,研究方向为团簇物理.E mai l:geguixian@1 引言在过去的十几年中,原子团簇的结构和稳定性得到了广泛的研究[1-3].近几年来, ~族化合物半导体材料奇特的光学性质和潜在的应用价值已引起物理、化学和材料等领域的广泛兴趣,也使得 ~族化合物团簇成为团簇领域的研究热点之一[4 6].对GaN团簇的研究工作主要有:Kan dalam等在密度泛函理论的基础上运用非局域密度近似的方法计算了Ga n N m(n,m=1~2)[7]和Ga n N n(n=3~6)[8,9]团簇的结构.Belbruno[10]等用密度泛函理论研究了Ga n N n(n=2~4)团簇的结构.Song等用全势能线形M uffin T in轨道组合分子动力学(FP LMTO)方法计算了Ga n N n(n=2 ~6)[11]团簇的结构.Costales等用密度泛函理论对Ga n N-n(n=1~3)[12]阴离子团簇进行了研究.以上小组的共同特点是主要集中在结构的研究上,都没有涉及到原子间的成键特性和极化率的计算.众所周知,极化率表征着体系对外场的响应,决定了体系的非线性光学特性,同时它还能够影响分子间如诱导力、色散力等长程相互作用以及碰撞过程中的散射截面等重要的物理量.本文用B3LYP/6 31G*密度泛函方法对Ga n N n(n=2~5)团簇进行了计算,得到了这些团簇的最低能量和一些亚稳态的几何结构,并对最稳定结构的电子性质、成键特性和极化率进行了分析.2 计算方法采用密度泛函理论(DFT)中的B3LYP泛函方法,在6 31G*水平上通过寻找对多维势能面上的极小点,在相同的水平上对振动频率进行了计算.所有的计算都是在Gaussian03程序[13]上进行的.为了验证所选方法的合理性,在相同的条件下计算了二聚体N2的键长和振动频率以及二聚体GaN 的键长.计算结果表明,N-N键长为0.1105nm、振动频率为2457.65cm-1,与实验的N-N键长0.1098nm,振动频率2358.57cm-1[14]符合的很好.Ga-N键长为0.173nm和最近Dsa计算的Ga-N键长(0.188nm)[15]符合的很好.由于B3LYP方法可以很好的描述二聚体N2和GaN,于是我们认为这种方法也适用于Ga n N n(n=2~5)团簇.3 结果与讨论3.1 几何构型Ga n N n(n=2~5)团簇的最低能量结构和一些亚稳态的几何结构如图1所示,原子间距分别小于0.3330nm(Ga-Ga),0.2432nm(Ga-N)及0. 1591nm(N-N)时成键,表1给出了最低能量结构的几何参数(原子括号内的数字代表第几个原图1 Ga n N n(n=2~5)团簇的最低能量结构和一些亚稳态的几何结构(浅色代表Ga原子,深色代表N原子)Fig.1 L owest energ y and some meta stable isomerstructures of Ga n N n(n=2~5)clusters(The w hite circles represent the Ga atoms and the dark circles represent th e N atoms)子).Ga2N2团簇的最低能量结构示于图1(2a),其是不规则的四边形,N-N键长为0.1168nm. Song等人[11]用FP LM TO方法报道的最低能量结构是一个菱形.他们报道的两个氮原子在短轴位置,N-N和Ga-N键长分别为0.1246nm和0.2093nm.我们在优化过程中得到了两种菱形结构,如图1(2b)和图1(2d)所示.其中2b的两个氮原子在短轴位置,N-N和Ga-N键长分别为0 1252nm和0.2151nm,与Song[11]的计算结果符合的很好.其能量仅比最低能量结构高0.007144 原子与分子物理学报第25卷eV,Kandalam[7]和Belbruno[10]在密度泛函理论的基础上运用非局域密度近似的方法均认为其是最低能量结构,没有报道出不规则的四边形.另外在优化过程中得到了三种线性构型,如图1(2c)、图1 (2e)和图1(2f)所示.Ga3N3团簇的最低能量结构如图1(3a)所示,该结构是一个平面,可以看成是一个N3单元与三个镓原子的结合,N3单元中N (3)-N(1)-N(2)的键长分别为0.1296nm和0. 1319nm.这和Song等[11]报道的Ga3N3团簇的最低能量结构以及N3单元中氮原子之间的键长0. 1295nm和0.1314nm符合的很好.Ga3N3团簇的最低能量结构的同分异构体(图1(3b))是一个C2v 的平面结构,其能量比最低能量结构高1.165eV,而Kandalam等[8]认为其是最低能量结构.图1中的3d是一个D3h的环形结构,能量比最低能量结构高2.988eV,Belbruno等[10]认为其是最低能量结构.在优化的所有结构中3c是唯一的一个立体结构,其能量比最低能量结构高1.607eV.Ga4N4团簇的最低能量结构是一个平面,如图3(4a)所示,该结构可以看成是一个N2单元与Ga4N2的结合,结构中的N(3)-N(1)键长为0.1105nm和N2负离子的键长0.1202nm非常接近.立体结构4b的能量比最低能量结构高0.397eV.另两个立体结构如图(4c)和(4d)所示,4c比最低能量结构高0.436eV,4d比最低能量结构高0.437eV,而4c和4d的能量仅差0.001eV,所以二者可看成是简并的.Belbruno[10]提出的Ga4N4的最稳定结构是一个D4h的平面结构,见图1(4f),在我们的计算中这种平面结构比最低能量结构高3.793eV,在所有同分异构体中能量最高.在优化的Ga4N4团簇的结构中,4f中有8个Ga-N键而没有N-N键,可见Ga-N键的增多和N-N键数目的断裂均会降低团簇的稳定性.Ga5N5团簇的最低能量结构如图1(5a)所示,该结构是一个平面结构,存在一个N3单元,N(1)-N(2)-N(3)的键长分别为0 1145nm和0.1221nm,仍和传统的直线N3负离子的键长(0.1183nm)偏离很小,N3单元与Ga(6)原子的键长为0.1948nm.立体结构5b 的能量比最低能量结构高0.379eV.平面结构5c 的能量比最低能量结构高1.022eV,Kandalam 等[8]认为其是最低能量结构.从得到的Ga n N n(n =2~5)团簇的几何结构来看,Ga n N n(n=2~5)的最稳定结构大多是平面结构,结构中存在着N2和N3单元.这说明N-N键在氮化镓团簇的形成中确实起着决定性的作用,Ga Ga之间不易成键,从这一点来看,本文的结果支持了Kandalam等的结果.3.2 能隙对于半导体材料来说,禁带与导带之间的能量间隔是非常重要的数据,GaN晶体(铅锌矿)的禁带和导带之间的能量差为3.44eV.那么对于半导体团簇来说,这个数据可以用最高占据分子轨道和最低未占据分子轨道的能量间隔(能隙)来反映.能隙差的大小反映了电子从占据轨道向未占据轨道发生跃迁的能力,在一定的程度上代表分子参与化学反应的能力.如表1所示,对于Ga n N n(n=2 ~5)团簇来说,随着团簇尺寸的增加,能隙整体呈增大的趋势,这说明团簇的化学活性逐渐减小.该团簇的能隙在1.776eV~ 3.563eV之间,所以从能隙上来看,Ga n N n(n=2~5)团簇已具有了半导体的性质.在Ga n N n(n=2~5)团簇中,Ga4N4团簇的能隙最大,说明Ga4N4比近邻尺寸的团簇稳定.3.3 分子轨道与成键分子的最高占据轨道(HOM O)和次最高占据轨道(NHOMO)的成键方式与形状直接反映了化学键结构的特点,通过对它们的分析,可以得到分子几何构型稳定性的信息.图2分别给出了Ga n N n(n=2~5)团簇最稳定结构的H OM O和次最高占据轨道(NH OMO),由图2可以看出,Ga2N2的HOMO是主要是由Ga和N原子的s、p轨道组成,有部分的d成分.HOMO可分为三部分:N-N的离域反键轨道,Ga-N的离域成键轨道和Ga-Ga的成键轨道.Ga2N2的NHOMO也可分为三部分:N-N的离域成键轨道,Ga-N 之间的成键轨道,Ga-Ga的反键轨道.从自然键轨道(natural bond orbital,NBO)分析也可以看出Ga、N原子主要发生了sp杂化,且有部分的d成分.由以上分析可以看出HOM O和NHOM O 对分子中的Ga-N和N-N成键都有贡献.Ga3N3的HOM O主要由三部分:N-N的离域成键轨道,Ga-N的离域成键轨道,Ga(6)和N(3),Ga(4)和N(3)以及Ga(4)和N(2)的成键轨道.Ga3N3的NH OM O主要由三部分:Ga(4)和N(2)原子之间的离域成键轨道,Ga(6)和N (3),Ga(5)和N(2)之间的成键轨道,N原子之间的离域成键轨道.从上面的分析可以看出,145第1期葛桂贤等:第一性原理对Ga n N n(n=2~5)小团簇的结构及电子性质的研究图2 G a n N n(n=2~5)团簇的最高占据分子轨道(HO M O)和次最高占据分子轨道(NHOM O)Fig.2 Contour maps of t he HOM Os and NHO M Os for the lowest energy structur e of Ga n N n(n=2~5)clusters表1 Ga n N n(n=2~5)团簇最稳定结构的对称性,键长( ),结合能E b(eV)和能隙(eV)T able1 Symmetry,bond,length,average binding ener gy(E b)and HOM O LU M O gap for the lo west ener gy structures of Ga n N n(n=2~5)clustersClusters Structure Symmetry Bond length(nm)E b(eV)Gap(eV) Ga2N2(2a)(Cs)N(3) N(4)0.1168 4.267 1.776 Ga2N2(2b)(D2h)N(1) N(2)0.1252 4.265Ga3N3(3a)(Cs)N(3) N(1)0.1296N(2) N(1)0.1319N(2) Ga(5)0.1953 4.403 3.012N(3) Ga(6)0.2015Ga4N4(4a)(Cs)N(1) N(3)0.1105N(2) Ga(8)0.1832N(2) Ga(7)0.1708N(4) Ga(7)0.1826 4.725 3.563N(4) Ga(5)0.1933N(4) Ga(6)0.1931Ga5N5(5a)(Cs)N(2) N(1)0.1145N(2) N(3)0.1221N(3) Ga(6)0.1948N(4) Ga(6)0.1848 4.744 3.229N(4) Ga(5)0.1928N(4) Ga(7)0.1931N(10) Ga(6)0.1834N(10) Ga(8)0.1981HOMO和NH OM O对N-N的成键和Ga-N的成键都有贡献.从Ga4N4的HOM O中可看出Ga、N原子发生了sp杂化,Ga-N是成键轨道,N-N之间的电子云分布很少,所以HOM O对N-N成键没有贡献.从NHOM O可看出Ga(7),N(2)和Ga(8)形成离域的大成键轨道,N(4)-Ga(5)和N(4)-Ga (6)都是成键轨道,N(1)和N(3)之间是三键,N146 原子与分子物理学报第25卷-N之间的电子云分布很少,NHOMO对N-N成键没有贡献.Ga5N5的HOM O和NHOMO的如图2中所示,从图上可以看出H OM O和NHOM O对Ga-Ga的成键都没有贡献,但对Ga-N的成键有贡献,而HOMO对N-N之间的成键有部分贡献. 3.3 Ga n N n(n=2~5)团簇的极化率用B3LYP方法在6 31G*水平上对Ga n N n(n =2~5)团簇的极化率进行了计算,并且由(1),(2)式计算得到了极化率张量的平均值<a>、极化率的各相异性不变量a和每个原子的平均线性极化率<a>/n.由此来衡量分子产生非线性光学性质能力的强弱:<!>=13(!XX+!YY+!ZZ)(1) !=(!XX-!Y Y)2+(!Y Y-!ZZ)2+(!ZZ-!XX)221/2.(2)从表2可以看出,单位原子的平均极化率整体上呈下降的趋势,但变化不大,表明团簇的电子结构随着原子数目的增加略显紧凑;极化率的各相异性不变量单调增加,说明团簇还没有形成密堆积结构,这与优化的团簇最稳定结构都是平面结构相一致.表2 Ga n N n(n=2~5)团簇最稳定结构的极化率张量、极化率张量的平均值<a>、极化率的各相异性不变量a和每个原子的平均线性极化率<a>/nT able2 Polarizabilit y tensor(!ij),po larizability(<!>),stat ic mean polarizabilities(<!>/n) and polarizability anisotro pies( !)of Ga n N n(n=2~5)clustersPolarizabilityClusters!XX!X Y!Y Y!XZ!YZ!ZZ<a><a>/n a Ga2N2142.8237.38382.690.0000.00059.15994.8923.7274.73 Ga3N3176.287 5.717152.9700.0050.00092.377140.5423.4275.020 Ga4N4265.580 5.988172.899-0.005-0.131109.216182.5622.82123.203 Ga5N5262.887-21.468253.9850.0000.003129.798215.5621.56128.8694 结语本文用DFT在6/31G*的水平上对Ga n N n(n =2~5)团簇的结构、电子性质、成键特性和极化率进行了研究.结果表明,Ga n N n(n=2~5)团簇的最稳定结构为平面结构,还没有形成密堆积结构,结构中存在N2和N3单元,N-N键在团簇的形成过程中起着决定性的作用,Ga-Ga之间不易成键.通过对能隙的分析可以看出Ga n N n(n=2~5)团簇具有半导体性质.参考文献:[1] Zhao W J,Y an Y L,Y ang Z,et al.F irst principlesstudy of the ground state str uctures and electronic propert ies of Li N Be(N=1~12)clusters[J].J.A t.M ol.Phys.,2007,24:716(in Chinese)[赵文杰,闫玉丽,杨致,等.第一性原理计算L i N Be(N=1~12)团簇的基态结构及其电子性质[J].原子与分子物理学报,2007,24:716][2] Lei X L,Yan Y L,Ge G X,et al.Gr ound state g eo metries and stability of Be n L i(n=1~12)clustersw ith density functional theory[J].J.A t.Mol.Phy s.,2007,24:1003(in Chinese)[雷雪玲,闫玉丽,葛桂贤,等.密度泛函理论计算掺杂团簇Be n L i (n=1~12)的基态结构和稳定性[J].原子与分子物理学报,2007,24:1003][3] Yang Z,Y an Y L,Ge G X,et al.Density functio nalstudy of g round structures and electr onic properties ofL i2Be N(N=1~10)clusters[J].J.A t.Mol.Phy s.,accepted(in Chinese)[杨致,闫玉丽,葛桂贤,等.利用密度泛函理论计算L i2Be N(N=1~10)团簇的最低能量结构及其电子性质[J].原子与分子物理学报,已被接受][4] Wang B L,Zhao J J,Shi D,et al.Density functio nalstudy of structural and electro nic properties of Al n N(n=2~12)clusters[J].Phy s.Rev.A,2005,72:023204[5] Guo L,Wu H S,Jin Z H.F irst principles investig atio nof geomet ry and stability of aluminum phosphorous binary clusters A l n P-m(n+m=5)[J].J.A t.Mol.Phy s.,2004,21:335(in Chinese)[郭玲,武海顺,金志浩.第一原理对Al n P-m(n+m=5)团簇结构和稳定性研究[J].原子与分子物理学报,2004,21:147第1期葛桂贤等:第一性原理对Ga n N n(n=2~5)小团簇的结构及电子性质的研究335][6] L i E L,Chen G C,Wang X W,et al.F irst principlesstudy on structures and photoelectron spectroscopy aboutGa n P-m anions[J].J.A t.M ol.Phys.,2006,23:279(in Chinese)[李恩玲,陈贵灿,王雪文,等.第一性原理对Ga n P-m阴离子团簇结构及其光电子能谱的研究[J].原子与分子物理学报,2006,23:279] [7] Kandalam A K,Randey P,Blanco M A,et al.Firstprinciples study of polyatomic clusters of AlN,GaN,and InN. 1.Structure,stabilit y,vibrations,and ionization[J].J.Phy s.Chem.B,2000,104:4361 [8] K andalam A K,Blanco M A,P andey R.T heoreticalstudy of structural and v ibrational properties of A l3N3,Ga3N3,and In3N3[J].J.Phys.Chem.B,2001,105:6080[9] K andalam A K,Blanco M A,P andey R.T heoreticalstudy of Al n N n,Ga n N n and In n N n(n=4~6)clusters[J].J.Phys.Chem.B,2002,106:1945[10] Belbr uno J J.T he structur e of small gallium nitrideclusters[J].H eter oatom Chemistry,2000,11:281 [11] Song B,Ling L,Cao P L.T heoretical study of thestructure of small GaN Clusters[J].Jour nal of ZhenJ iang University,2004,31:270[12] Costales A,P andey R.Density functio nal calculationsof small anionic clusters of gr oup nitr ides[J].J.Phys.Chem.A,2003,107:191[13] Frisch M J,T rucks G W,Schlegel H B,et al.Gaussian03,Revision C.02.Wallingford CT:Gaussian,Inc.,2004.[14] L ide D R.CRC H andbook of chemistry and p hy sics[M].79th ed.N ew Yor k:CRC Press,1998. [15] Das G P,Rao B K,Jena P.Ferromagnet i sm in M ndoped G aN:from clusters to crystals[J].Phys.Rev.B,2003,68:035207148 原子与分子物理学报第25卷。

六硼化钇纳米粒子超导及光吸收性能研究

第50卷第3期2021年5月内蒙古师范大学学报(自然科学版)Journal of Inner Mongolia Normal University(Natural Science Edition)Vol.50No.3May2021六硼化钇纳米粒子超导及光吸收性能研究王军】，包黎红】，潮洛蒙2（1.内蒙古师范大学物理与电子信息学院，内蒙古呼和浩特010022；2.内蒙古科技大学理学院，内蒙古包头014010）摘要：采用固相烧结法成功制备出了六硼化钇（YB&）纳米粒子，首次系统研究了该纳米粉末超导及光吸收性能.结果表明，当超导转变温度T=2.75K时由正常态转变为超导态，其临界磁场为H c2=0.18T.为进一步研究YB6纳米粒子电-声子相互作用机理，采用拉曼光谱对声子振动频率进行了测量，结合McMillan公式计算出YB6纳米粒子电-声子作用常数为A=0.63,该值远小于单晶块体YB6的1.01.为进一步解释其原因，采用高分辨透射电镜对晶体缺陷进行了详细表征.结果发现，晶体缺陷导致其声子振动频率的改变，从而降低了纳米YB6电-声子相互作用常数.光吸收结果表明YB6纳米粒子吸收谷波长为785nm,对可见光具有很强的穿透性.关键词：超导性；光吸收；YB6中图分类号：O511+.3文献标志码：A文章编号：1001—8735（2021）03—0204—06doi：10.3969/j.issn.1001—8735.2021.03.003众所周知，材料的宏观物理化学性能与微观结构密切相关[12].特别是当材料晶粒尺寸减小到纳米尺度后，纳米晶材料不仅具有亚稳态的特点，而且相比于粗晶材料展现出许多新奇的物理化学性能.与此同时,材料的纳米化会改变材料电子态密度及电-声子相互等物理量，从而会对超导及光学性能有很大的影响[34].因此，如何将纳米材料微观结构与宏观性能之间进行有效关联，将对材料新性能的发现和研究具有重要作用.在众多金属硼化物中，由于六硼化钇YB6具有第二高超导转变温度T c=&4K,故其超导性能受到广泛关注.目前关于这方面的研究主要集中于单晶YB6块体材料上[8],而对于YB6纳米离子超导性能研究未见报道.研究者们为了解释单晶块体超导机理及提高临界转变温度，系统研究了压强对YB6单晶块体晶体结构和声子振动的影响[912].结果发现，当压强从0增加至40GPa时，电子-声子相互作用常数从1.44减小到0.44.与此同时，相对应的超导转变温度也从&9K减小到1.4K,表明压强对电-声子作用具有很大影响.这项研究工作的一个重要提示是,YB6的纳米化是否会改变费米能级周围的电子态密度及电子-声子相互作用，从而展现出一些新的超导性能，这是本文的重要研究内容之一.此外，虽然YB6与LaB6具有相同立方晶体结构[13],但它是否同样具有对可见光的高穿透特性，是本论文另一个重要研究内容.目前国内外对纳米YB6超导性能及光吸收实验方面的系统研究未见报道.本文首次系统研究了YB6纳米粒子超导及光吸收性能.为进一步揭示材料微观结构与宏观性能之间的内在关联，采用高分辨透射电镜和拉曼光谱等测量手段对微观结构进行了有效表征，并对超导及光吸收机理进行探讨.收稿日期：2020-11-30基金项目：国家自然科学基金资助项目（51662034）；内蒙古自治区自然科学基金资助项目（2019LH05001）；内蒙古自治区留学人员创新创业启动基金资助项目.作者简介：王军（1992-），男，内蒙古阿拉善左旗人，在读硕士研究生，主要从事纳米稀土六硼化物光吸收及热发射性能研究.通讯作者：包黎红（1983—）,男，内蒙古兴安盟人，教授，博士，主要从事纳米金属硼化物物理性能研究,E-mail:baolihong@.第3期王军等：六硼化钇纳米粒子超导及光吸收性能研究-205-1材料与方法将无水氯化钇(YCl,纯度99.95%)和硼氢化钠(NaBH4,纯度98%)粉末在空气中按摩尔比为1：&8混合研磨10〜15min.将混合均匀的粉末放入压机中，在压强为10GPa下预压成块，将其装入石英管中进行真空烧结.反应温度为1100C,保温2h.由于固相反应后产物中有YBO s的杂相，故对烧结后产物分别使用稀盐酸，蒸馏水，无水乙醇等溶液进行多次清洗.采用场发射扫描电子显微镜(日立SU-8010)和X射线衍射仪(飞利浦PW1830,CuKa)对YB6纳米粒子的物相及形貌进行表征.采用PPMS测量仪对纳米YB6交流磁化率和临界磁场进行了测量，最低温度为1.8K.采用透射电子显微镜(FEITecnai F20S-Twin200kv)观察微观结构.拉曼散射由拉曼光谱仪(LabRamHR,波长：514.5nm,激光源:Ar+)进行测量.采用分光光度计(UH4150)在光源波长350〜2500nm范围内测量其光吸收。

First-principles calculations of electronic

First-principles calculations of electronic structure and optical properties of Boron-doped ZnO with intrinsicdefectsYen-Chun Peng,Chieh-Cheng Chen,Hsuan-Chung Wu ⇑,Jong-Hong LuDepartment of Materials Engineering,Ming Chi University of Technology,New Taipei 24301,Taiwana r t i c l e i n f o Article history:Received 11August 2014Received in revised form 27October 2014Accepted 27October 2014Available online 15November 2014Keywords:First principles B-doped ZnO Intrinsic defectElectronic structure Optical propertya b s t r a c tThis study adopted ﬁrst-principles calculations to evaluate the effects of intrinsic defects on the elec-tronic structure and optical properties of Boron-doped ZnO (BZO).Four types of defect were considered:non-defective (B Zn ),Zn vacancies (V Zn ),O vacancies (V O ),and interstitial Zn (Zn i ).Calculations of forma-tion energy illustrate that O-rich conditions tend to induce V Zn ,while O-poor conditions tend to induce V O and Zn i .With respect to electric properties,V Zn defects in BZO decrease carrier concentration as well as mobility,which consequently decreases the conductivity of BZO.The existence of V O or Zn i defects in BZO leads to n-type conductive characteristics and increases the optical band gap.The existence of Zn i defects in BZO also increases the effective mass,which decreases the mobility and conductivity of BZO.As for the optical properties,the introduction of V Zn to BZO leads to an increase in transmittance in the visible light region,but a decrease in the UV region.The introduction of intrinsic V O and Zn i defects to BZO leads to a signiﬁcant decrease in transmittance in the visible as well as UV regions.The calculated results were also compared with experimental data from the literature.Ó2014Elsevier B.V.All rights reserved.1.IntroductionZnO is an abundant,non-toxic material with a wide band gap (3.37eV)and transparent properties under visible light.ZnO has recently attracted considerable attention as an alternative for Tin-doped In 2O 3(ITO),which is currently the most common choice of transparent conductive oxide for a variety of applications [1,2].The resistivity of pure ZnO is on the order of 10À2X -cm,which is far higher than that of ITO (10À4X -cm order).A great deal of research has gone into enhancing the conductivity of ZnO through the addition of various dopants,which can mainly be divided into metals [3–5]and non-metals [6,7].B-doped ZnO (BZO)thin ﬁlm shows considerable promise for its superior photoelectric proper-ties and stability [8,9].Many groups have investigated the effects of process parameters on the electric and optical properties of BZO thin ﬁlm,with the aim of optimizing performance [7–13].Miyata et al.[7]indicated that the transmittance of BZO thin ﬁlm could be improved through the introduction of O 2gas from 0sccm to 10sccm.David et al.[10]reported that annealing temperature and atmosphere strongly affect the conductivity of BZO.Yang et al.[11]concluded that the low oxygen partial pressure during deposition increases the carrier density of oxygen vacancies,which leads to a strong decline in resistivity.However,resistivity in sam-ples produced under the high oxygen partial pressure is far higher than in samples deposited under low oxygen partial pressure,which suggests the existence of p-type carriers of Zinc vacancies in ﬁlms grown under high oxygen partial pressure.Patil et al.[12]synthesized B-doped ZnO powders using a mechanochemical method.The photoluminescence (PL)spectra at room temperature is an indication that a greater number of oxygen vacancies exist in nonmetal-doped ZnO,compared to pure ZnO.In the fabrication of BZO microrods,Yılmaz et al.[13]investigated the inﬂuence of B diffusion doping on optical emission and defect formation.PL spec-tra results revealed that the intensity of the deep level visible band emission increases with an increase in annealing time,which implies a signiﬁcant increase in the concentration of intrinsic defects.As outlined above,various process conditions inﬂuence the type and number of intrinsic defects with a subsequent inﬂuence on the electric and optical properties of BZO.Gaining a comprehensive understanding of the electric and optical characteristics of BZO would require in-depth study into the effects of intrinsic defects on the properties of BZO.First-principles calculations can provide information concerning materials at the microscopic scale to eluci-date the connection between structure and properties.It is well known that the use of conventional density functional theory/10.1016/j.optmat.2014.10.0580925-3467/Ó2014Elsevier B.V.All rights reserved.⇑Corresponding author at:Department of Materials Engineering,Ming Chi University of Technology,84Gungjuan Road,Taishan,New Taipei 24301,Taiwan.Tel.:+8862290898994675;fax:+886229084091.E-mail address:hcwu@.tw (H.-C.Wu).(DFT)leads to a considerable underestimation of the calculated band gap in ZnO [14–16].In our previous study [17],we used the DFT plus Hubbard U (DFT +U)method to avoid underestimat-ing the band gap.This approach reduced the differences in calcu-lated band gap and lattice constant to within 1%of the experimental values.The current study extended the utilization of the DFT +U method to calculate and analyze the effects of intrin-sic defects (V Zn ,V O ,and Zn i )on the formation energy,crystal struc-ture,electronic structure,and optical properties of BZO.These results clarify the connections among the fabrication process,structure,and properties of BZO,for use in determining the criteria for future material designs.2.Calculation methodsThis study considered a 2Â2Â2supercell of a Wurtzite ZnO,including 16Zn atoms and 16O atoms,as shown in Fig.1.A B-monodoping model was constructed by substituting one Zn atom (number 1site)with one B atom (B Zn model),which correspond to the B concentrations of 6.25at.%.We also considered three intrinsic defects in the B Zn structure,in which Zn vacancies(B Zn V Zn ),O vacancies (B Zn V O ),and interstitial Zn (B Zn Zn i )are repre-sented as 2,3,and 4,respectively.The V Zn ,V O ,and Zn i concentra-tions corresponds to doping levels of 6.25, 6.25,and 5.88at.%,respectively.The defect concentration could be reduced using a larger supercell for the real systems;however,this study was lim-ited with regard to computer resources.Therefore,the properties of the defects calculated from a 2Â2Â2ZnO supercell such as this could be used as qualitative analysis.1432ZnO BTable 1Formation energy and optimized structure of BZO with varying intrinsic defects.Formation energy (eV)Optimized structure O-richO-poor Zn–O (Å)B–O (Å)4V (%)ZnO –– 1.981––B Zn3.750.39 1.996 1.526À3.1B Zn V Zn 5.68 5.81 1.993 1.530À3.3B Zn V O 7.550.70 1.995 1.521À5.3B Zn Zn i10.513.662.0031.5174.74.5 eV2.15 eV3.25 eV4.68 eV4.41 eV(a)(b)(c)(d)Band structures of B-doped ZnO for (a)B Zn ,(b)B Zn V Zn ,(c)B Zn V O models.Y.-C.Peng et al./Optical Materials 39(2015)34–3935All models presented in this study were developed using CASTEP software [18].Structural optimization was performed on each model before calculating properties.The Monkhorst–Pack scheme [19]K-points grid sampling in the supercells was set at 4Â4Â2.Electron–ion interactions were modeled using the ultrasoft pseudo-potential method [20].The valence conﬁgurations of the atoms were 4s 23d 10for Zn,2s 22p 4for O,and 2s 22p 1for B.The elec-tron wave functions were expanded in plane wave with an energy cutoff of 380eV.In the structural optimization process,the change in energy,maximum force,maximum stress,and maximum displacement tolerances were set at 10À5eV/atom,0.03eV/Å,0.05GPa,and 0.001Å,respectively.The energy convergence crite-rion for the self-consistent ﬁeld was set at 10À6eV.To describe the electronic structures more accurately,we adopted the DFT +U d +U p method [21],in which the U d value for Zn-3d and the U p value for O-2p orbitals were set at 10and 7eV,respectively.The band structures,band gaps,and Zn-3d orbital locations of pure ZnO,which were used for the selection of U d and U p values,can be referenced in our previous research [17,22].3.Results and discussion 3.1.Optimized structureThe average bond lengths and volume difference ratio,as obtained from geometric optimization,are summarized in Table 1.In pure ZnO,each Zn atom is bonded to its three horizontal and one vertical oxygen neighbors.The average bond length of Zn-O is 1.981Åand optimized lattice constants are a =b =3.249Åandc =5.232Å,which are in agreement with the experimental values of a =b =3.249,c =5.206Å[23].Following the substitution of one B atom for one Zn atom (B Zn model),the Zn–O bond length is longer than that of B–O (1.526Å).This is because the B 3+radius (0.27Å)is smaller than that of Zn 2+(0.74Å)[24].Therefore,the cell volume of B Zn model shrinks,which is consistent with the experi-mental results [25].Clearly,the presence of Zn or O vacancies in BZO also leads to a shrinkage in volume.Conversely,the presence of interstitial Zn leads to a longer Zn–O length and expansion in volume.3.2.Formation energyTo examine the relative stability of BZO with intrinsic defects in neutral charge state,the defect formation energy can be expressed as follows:[26,27]E f ðD Þ¼E tot ðD ÞÀE tot ðZnO ÞþXn i l ið1Þwhere E tot (ZnO)and E tot (D )are the total energy in pure ZnO and in the defective systems,respectively.n i is the number of i atoms removed from or added to the supercell.If an atom is removed from the supercell,n i is positive,otherwise is negative.l i is the chemical potential of atom i .Formation energy depends on the growth envi-ronment during the preparation process,which can be O-rich or O-poor (Zn-rich).In thermo-dynamic equilibrium,D l Zn +D l O =D H f (ZnO),where D H f (ZnO)represents the formation enthalpy of ZnO.For the chemical potential of B,this study adopted the relation of 2D l B +3D l O 6D H f (B 2O 3)under O-rich conditions and l B =l B(bulk)under O-poor conditions,where D H f (B 2O 3)represents the(a)(b)(c)(d)V ZnV OZn iBZnOO density difference for (a)B Zn ,(b)B Zn V Zn ,(c)B Zn V O ,and (d)B Zn Zn i models.The red,orange,yellow,green,and interpretation of the references to color in this ﬁgure legend,the reader is referred to the web version 36Y.-C.Peng et al./Optical Materials 39(2015)34–39formation enthalpy of B2O3.D l i represents the chemical potential of atom i referred to as the elemental solid/gas of l i(bulk/molecule).It is well known that a defective structure with lower formation energy forms more readily and denotes an increased occurrence of defects.Table1presents a summary of the calculated formation energy of BZO with various intrinsic defects,based on the neutral charge state.With the existence of B Zn,E f(B Zn V Zn)<E f(B Zn V O)<E f (B Zn Zn i)under O-rich conditions,implying that O-rich conditions are more likely to induce the formation of V Zn,followed by V O and Zn i.Under O-poor conditions,E f(B Zn V O)<E f(B Zn Zn i)<E f (B Zn V Zn),which implies that O-poor conditions are more likely to induce the formation of V O.As a result,process conditions,such as O2gasﬂow rate and substrate temperature,largely determine the type of intrinsic defects that form in BZO during preparation. The occurrence of V O is far more likely under a low-O atmosphere, and V Zn is more likely to occur under a high-O atmosphere.For the sake of comparison,we also calculated the formation energy of a single intrinsic defect(V Zn and V O)in pure ZnO.The calculated values of E f(V Zn)and E f(V O)are3.09and4.33eV under O-rich conditions and6.58and0.84eV under O-poor conditions. Thus,we can see that the formation energy of a Zn vacancy from pure ZnO(E f(V Zn))is greater than that obtained from BZO(E f(B Zn V Zn)ÀE f(B Zn)=1.93eV under O-rich conditions and5.42eV under O-poor conditions).This demonstrates that Zn vacancies form more easily in BZO than in ZnO.These results are similar to those calculated for O vacancies,which implies that B-doping facilitates the formation of V Zn and V O.Previous studies [12]obtained similar results,indicating that a greater number of oxygen vacancies or defects exist in BZO than in pure ZnO.3.3.Electronic structureTo clarify the inﬂuence of intrinsic defects on the electronic structure of BZO,we calculated the band structure,difference in charge density,and density of states(DOS),as shown in Figs.2–4,respectively.In our previous study[17,22],the calculated band structure revealed a band gap of3.37eV in pure ZnO,which is in excellent agreement with values obtained in experiments.In the present study,we focus on the properties of BZO with intrinsic defects.Fig.2presents the band structures for BZO with various intrin-sic defect models.The Fermi level indicated by the dotted line was set to zero.Fig.2(a)shows the situation in which a Zn atom in pure ZnO is replaced by a B atom,in which the Fermi level shifts from the valence band(VB)maximum to the bottom of the conduction band(CB),resulting in a shallow donor level at the bottom of the CB.The shallow donor level at B doping causes an increase in the optical band gap to4.5eV at B concentration of6.25at.%,which is well known as the Burstein-Moss effect[28].The deﬁnitionof Fig.4.Density of states for(a)B Zn,(b)B Zn V Zn,(c)B Zn V O,and(d)B Zn Zn i models.optical band gap is from the top offor n-type semiconducting materials and the bottom of conduction band for materials.Similar tendencies were experiment-based studies[29,30].Asin the vicinity of B impurities appears atoms.The calculated Mulliken bond and B–O bonds are0.371and0.658, that a B–O bond is more covalent than Mulliken bond population represents characteristics).As shown in Fig.4(a),to the bottom of CB are the Zn-4s anda few O-2s and O-2p orbitals.The main extra electron toﬁll up the CBM.According to the results calculated regarded as an intrinsic defect under the B Zn V Zn model(Fig.2(b)),when donor levels coexist,the empty states produced trons from the B Zn donor level,resulting level as well as the formation of p-type band gap of B Zn V Zn can be narrowed to eration of conduction electrons requires energy from the Fermi level to the CB, be required in the B Zn model.Thus,in may lead to a decrease in the carrier known that mobility is related to the time.The relaxation time could not be software and was assumed as a defects in BZO.The followingeffects of the effective mass on thenear the Fermi level appear nearlyof carriers with a smaller curvature The larger effective mass is related toTherefore,V Zn defects in BZO reduce both carrier concentration as well as mobility,which consequently increases the resistivity of BZO.Fig.3(b)shows that the O atoms surrounding a Zn vacancy gain fewer electrons(green color),implying the occurrence of a number of empty states of O atoms.These empty states are O-2p orbitals near the Fermi level,as shown in Fig.4(b).V O and Zn i can be regarded as intrinsic defects in an O-poor environment.Fig.2(c)and(d)show the band structures in B Zn V O and B Zn Zn i models,in which n-type conductive characteristics appear and the optical band gap increases to4.68eV and4.41eV, respectively.One shallow donor state and one deep donor state occur in these two models.In the B Zn V O model,the deep donor level is probably the charge remaining in the oxygen vacancy (Fig.3(c));in the B Zn Zn i model,it is probably the covalence charge in the vicinity of the interstitial Zn atom(Zn i)(Fig.3(d)).Fig.4(c) and(d)show that the shallow donor level in both models origi-nated from B doping,whereas the deep donor level in the B Zn V O and B Zn Zn i models originated from the addition of V O and Zn i, respectively.The deep donor level in the B Zn V O model comprises mainly Zn and O atoms;however,in the B Zn Zn i model,it also includes B atom(B-2s and B-2p states).The shallow donor states provide conduction electrons;however,the deep donor states may contribute less to the increase in carrier concentration.Qual-itatively,the curvature of the energy band near the Fermi level in the B Zn Zn i model is smaller than that in the B Zn V O model.There-fore,Zn i defects present in BZO increase the effective mass,which may consequently decrease the mobility and conductivity of BZO.3.4.Optical propertiesThe optical properties can be described via the dielectric func-tion e(x)=e1(x)+i e2(x)[31].The imaginary part of the dielectric function e2(x)is calculated as follows:e2¼2e2pX e0Xk;v;cu ckuÁrj j u v k2d E ckÀE vkÀxÀÁð2Þwhere e is the electronic charge;X is the unit cell volume;u is the vector deﬁning the polarization of the incident electricﬁeld;x is the frequency of light;and u c k and u v k are the wave functions of the conduction and valence bands,respectively.Fig.5(a)shows the e2(x)of BZO with various intrinsic defects. In the B Zn model,a blue-shift in the intrinsic absorption edge occurred due to an enlarged optical band gap as compared with ZnO.The shallow donor levels mentioned in Section3.3resulted in an absorption peak at1.2eV.The absorption peaks in the intrin-sic defect models were as follows:B Zn V Zn(0.3eV),B Zn V O(1.5eV), and B Zn Zn i(0.9eV).These peaks resulted in enhanced absorption in the visible range.The peak of B Zn V Zn is the lowest,which can probably be attributed to the transition between occupied states and unoccupied states near the Fermi level.In the B Zn V O,and B Zn Zn i models,the absorption in the visible range may be the result of a shift from the shallow and deep donor occupied states to the unoccupied states of the conduction band.Fig.5(b)presents the transmittance of BZO under various defec-tive models.Table2presents the calculated values for average transmittance associated with each model under UV and visible light.It is should be noted that the calculated results were based on the doping levels of B(6.25at.%),V Zn(6.25at.%)V O(6.25at.%), and Zn i(5.88at.%).The average transmittance of pure ZnO is89.2 %in the visible region and65.6%in the UV region.Fig.5(b)shows that the incorporation of B into ZnO decreased transmittance in the range of800–1200nm(infrared region)and400–800nm(visible light region),but increased transmittance in the range of200–400nm(UV region),compared with pure ZnO.When V Zn was introduced to BZO,transmittance in the visible light region was Optical properties of BZO with varying intrinsic defects.(a)Imaginary dielectric function,(b)Transmittance.38increased,but transmittance in the UV region decreased,compared with BZO.When V O or Zn i was introduced to BZO,the transmit-tance of visible as well as UV light declined signiﬁcantly,which implies that transmittance could be reduced by employing a low-O environment for fabrication.This may explain why trans-mittance is enhanced by an increase in oxygen pressure during processing[7].4.ConclusionsThis study used the DFT+U method to investigate the inﬂuence of intrinsic defects on the formation energy,crystal structure,elec-tronic structure,and optical properties of BZO.Our results revealed that the formation energy of V Zn is lowest under O-rich conditions and the formation energy of V O is lowest under O-poor conditions. V Zn defects in BZO may decrease carrier concentration as well as mobility,which increases transmittance in the visible light region but decreases transmittance in the UV region.V O or Zn i defects in BZO lead to the appearance of n-type conductive characteristics, increasing the optical band gap,and decreasing transmittance in the visible light and UV regions.In addition,Zn i defects increase the effective mass,which may consequently decrease the mobility and conductivity of BZO.Conﬂict of interestsThe authors declare that there is no conﬂict of interests regard-ing the publication of this article.AcknowledgementsThis work was supported by the National Science Council in Taiwan(NSC102-2221-E-131-008),for which the authors are grateful.We also acknowledge the National Center for High-performance Computing for computer time and the use of its facilities.Reference[1]T.Minami,Semicond.Sci.Technol.20(2005)S35–S44.[2]L.Zhao,G.Shao,S.Song,X.Qin,S.Han,Rare Metals30(2011)175–182.[3]V.Bhavanasi,C.B.Singh,D.Datta,V.Singh,K.Shahi,S.Kumar,Opt.Mater.35(2013)1352–1359.[4]C.Huang,M.Wang,Z.Deng,Y.Cao,Q.Liu,Z.Huang,Y.Liu,W.Guo,Q.Huang,J.Mater.Sci.–Mater.Electron21(2010)1221–1227.[5]J.L.Zhao,X.W.Sun,H.Ryu,Y.B.Moon,Opt.Mater.33(2011)768–772.[6]L.Cao,L.P.Zhu,W.F.Chen,Z.Z.Ye,Opt.Mater.35(2013)1293–1296.[7]T.Miyata,Y.Honma,T.Minami,J.Vac.Sci.Technol.A25(2007)1193–1197.[8]X.L.Chen,B.H.Xu,J.M.Xue,Y.Zhao,C.C.Wei,J.Sun,Y.Wang,X.D.Zhang,X.H.Geng,Thin Solid Films515(2007)3753–3759.[9]D.W.Kang,J.Y.Kwon,D.J.Lee,M.K.Han,J.Electrochem.Soc.159(2012)H61–H65.[10]C.David,T.Girardeau, F.Paumier, D.Eyidi, croix,N.Papathanasiou,B.P.Tinkham,P.Gu´erin,M.Marteau,J.Phys.:Condens.Matter23(2011)334209.[11]H.Yang,X.Xu,X.Zhou,Y.Ma,J.Dong,T.Wang,J.Miao,Y.Jiang,J.Mater.Sci.47(2012)6513–6516.[12]A.B.Patil,K.R.Patil,S.K.Pardeshi,J.Solid State Chem.184(2011)3273–3279.[13]S.Yılmaz,J.Nisar,Y.Atasoy,E.McGlynn,R.Ahuja,M.Parlak,E.Bacaksız,Ceram.Int.39(2013)4609–4617.[14]L.Li,W.Wang,H.Liu,X.Liu,Q.Song,S.Ren,J.Phys.Chem.C113(2009)8460–8464.[15]X.Qu,W.Wang,S.Lv,D.Jia,Solid State Commun.151(2011)332–336.[16]G.Ji,Z.Gu,M.Lu,J.Zhou,S.Zhang,Y.Chen,Physica B405(2010)4948–4950.[17]H.C.Wu,Y.C.Peng,C.C.Chen,Opt.Mater.35(2013)509–515.[18]M.D.Segall,P.J.D.Lindan,M.J.Probert,C.J.Pickard,P.J.Hasnip,S.J.Clark,M.C.Payne,J.Phys.:Condens.Matter.14(2002)2717–2744.[19]H.J.Monkhorst,J.D.Pack,Phys.Rev.B13(1976)5188–5192.[20]D.Vanderbilt,Phys.Rev.B41(1990)7892–7895.[21]X.Ma,B.Lu,D.Li,R.Shi,C.Pan,Y.Zhu,J.Phys.Chem.C115(2011)4680–4687.[22]H.C.Wu,Y.C.Peng,T.P.Shen,Materials5(2012)2088–2100.[23]R.D.Vispute,V.Talyansky,S.Choopun,R.P.Sharma,T.Venkatesan,Appl.Phys.Lett.73(1998)348–350.[24]D.R.Lide,CRC Handbook of Chemistry and Physics,87th ed.,Taylor andFrancis,Philadelphia,2006.[25]X.G.Xu,H.L.Yang,Y.Wu,D.L.Zhang,S.Z.Wu,Appl.Phys.Lett.97(2010)232502.[26]A.Janotti, C.G.Van de Walle,Phys.Rev.B:Condens.Matter.76(2007)165202.[27]T.Guo,G.Dong,Q.Chen,X.Diao,F.Gao,J.Phys.Chem.Solids75(2014)42–47.[28]P.V.Kamat,N.M.Dimitrijevic, A.J.Nozik,J.Phys.Chem.93(1989)2873–2875.[29]L.Gao,Y.Zhang,J.M.Zhang,K.W.Xu,Appl.Surf.Sci.257(2011)2498–2502.[30]B.N.Pawar,S.R.Jadkar,M.G.Takwale,J.Phys.Chem.Solids66(2005)1779–1782.[31]R.Chowdhury,S.Adhikari,P.Rees,Physica B405(2010)4763–4767.Table2Average transmittance of BZO with varying intrinsic defects.UV region(%)Visible region(%)ZnO65.689.2B Zn91.175.6B Zn V Zn68.186.8B Zn V O52.053.2B Zn Zn i59.256.9Y.-C.Peng et al./Optical Materials39(2015)34–3939。

BN

立方BN能带结构及其态密度分析摘要：应用VASP软件包分别用GGA计算方法和HSE计算方法分析了立方BN的能带结构和态密度。

计算结果表明BN是半导体，GAA计算出的带隙为3.98ev,而HSE计算得出的带隙要更宽。

能带在能量较低时主要由N2s态组成，BN的价带顶主要由N原子的2p态组成。

关键字：BN; 能带结构; 态密度Cubic BN band structure and density of statesAbstract:In application of V ASP package with GGA calculation method and HSE calculation method analysised the band structure and density of states of cubic BN.Calculation results show that BN is semiconductor, the GAA to calculation the band gap is 3.98ev, and calculation of HSE is more wide. Band in the low energy is mainly composed of N2s state, to the top of valence band of BN is mainly composed of N’s 2p states.Key words: BN; band structure; density of states1 引言立方氮化硼(cBN)是一种人工合成的半导体材料，具有良好的物理化学性质，在热学，力学，光学，电子学等方面有着广泛的应用前景，与碳相类似，氮化硼既有软的六角的sp2杂化结构又有硬的类金刚石的sp3杂化结构。

其四种相结构分别是与金刚石的闪锌矿结构对应的立方氮化硼（c-BN），与六角石墨对应的六角氮化硼（h-BN），与六方金刚石对应的纤锌矿氮化硼（w-BN）和与三方菱面体结构的石墨对应的菱形氮化硼（r-BN），其中sp2杂化的h-BN 和sp3杂化的c-BN 为稳定态结构，而sp2杂化的r-BN 和sp3杂化的w-BN 为非稳定结构。

First-principle study of excitonic self-trapping in diamond

a rXiv:mtrl -th/9522v14Fe b1995First-principle study of excitonic self-trapping in diamond Francesco Mauri ∗and Roberto Car Institut Romand de Recherche Num´e rique en Physique des Mat´e riaux (IRRMA)IN-Ecublens 1015Lausanne,Switzerland Abstract We present a ﬁrst-principles study of excitonic self-trapping in diamond.Our calculation provides evidence for self-trapping of the 1s core exciton and gives a coherent interpretation of recent experimental X-ray absorption and emission data.Self-trapping does not occur in the case of a single valence exciton.We predict,however,that self-trapping should occur in the case of a valence biexciton.This process is accompanied by a large local relaxation of the lattice which could be observed experimentally.PACS numbers:61.80.−x,71.38.+i,71.35+z,71.55.−iTypeset using REVT E XDiamond presents an unusually favorable combination of characteristics that,in connection with the recent development of techniques for the deposition of thin diamondﬁlms,make this material a good candidate for many technological applications.Particularly appealing is the use of diamond in electronic or in opto-electronic devices,as e.g.UV-light emitting devices.Moreover,diamond is an ideal material for the construction of windows that operate under high power laser radiation or/and in adverse environments.It is therefore interesting to study radiation induced defects with deep electronic levels in the gap,since these can have important implications in many of these applications.Excitonic self-trapping is a possible mechanism for the formation of deep levels in the gap.The study of such processes in a purely covalent material,like diamond,is interesting also from a fundamental point of view.Indeed,excitonic self-trapping has been studied so far mostly in the context of ionic compounds,where it is always associated with,and often driven by,charge transfer eﬀects.In a covalent material the driving mechanism for self-trapping is instead related to the diﬀerence in the bonding character between the valence and the conduction band states.Both experimental data and theoretical arguments suggest the occurrence of self-trapping processes in diamond.In particular,a nitrogen(N)substitutional impurity induces a strong local deformation of the lattice[1–3]that can be interpreted as a self-trapping of the donor electron.The structure of a1s core exciton is more controversial[4–9].Indeed the similarity between an excited core of carbon and a ground-state core of nitrogen suggests that the core exciton should behave like a N impurity.However,the position of the core exciton peak in the diamond K-edge absorption spectra is only0.2eV lower than the conduction band minimum[4,7,8],while a N impurity originates a deep level1.7eV below the conduction band edge[10].On the other hand,emission spectra[8]suggest that a1s core exciton should self-trap like a N impurity.Finally,we consider valence excitations.In this case experimental evidence indicates that a single valence exciton is of the Wannier type,i.e.there is no self-trapping.To our knowledge,neither experimental nor theoretical investigations on the behavior of a valence biexciton in diamond have been performed,although simple scalingarguments suggest that the tendency to self-trap should be stronger for biexcitons than for single excitons.In this letter,we present a detailed theoretical study of excitonic self-trapping eﬀects in diamond.In particular,we have investigated the Born-Oppenheimer(BO)potential energy surfaces corresponding to a core exciton,a valence exciton and a valence biexciton in the context of density functional theory(DFT),within the local density approximation(LDA) for exchange and correlation.Our calculation indicates that the1s core exciton is on a diﬀerent BO surface in absorption and in emission experiments.Indeed X-ray absorption creates excitons in a p-like state as required by dipole selection rules.Subsequently the system makes a transition to an s-like state associated to a self-trapping distortion of the atomic lattice,similar to that found in the N impurity case.These results provide a coherent interpretation of the experimental data.In addition,our calculation suggests that self-trapping should also occur for a valence biexciton.This is a prediction that could be veriﬁed experimentally.Let us start by discussing a simple model[11,12].In diamond,the occupied valence and the lower conduction band states derive from superpositions of atomic sp3hybrids having bonding and antibonding character,respectively.Thus,when an electron,or a hole,or an electron-hole pair is added to the system,this can gain in deformation energy by relaxing the atomic lattice.Scaling arguments suggest that the deformation energy gain E def∝−1/N b, where N b is the number of bonds over which the perturbation is localized.This localization,due to quantum conﬁnement.The in turn,has a kinetic energy cost E kin∝+1/N2/3bbehavior of the system is then governed by the value of N b that minimizes the total energy E sum=E def+E kin.Since the only stationary point of E sum is a maximum,E sum attains its minimum value at either one of the two extrema N b=1or N b=∞.If the minimum occurs for N b=1,the perturbation is self-trapped on a single bond which is therefore stretched.If the minimum occurs for N b=∞,there is no self-trapping and the perturbation is delocalized.When N p particles(quasi-particles)are added to the system,one can showthat,for a given N b,E def scales as N2p,while E kin scales as N p.As a consequence,the probability of self-trapping is enhanced when N p is larger.This suggests that biexcitons should have a stronger tendency to self-trap than single excitons[12,13].In order to get a more quantitative understanding of self-trapping phenomena in dia-mond,we performed self-consistent electronic structure calculations,using norm-conserving pseudopotentials[14]to describe core-valence interactions.The wave-functions and the electronic density were expanded in plane-waves with a cutoﬀof35and of140Ry,respec-tively.We used a periodically repeated simple cubic supercell containing64atoms at the experimental equilibrium lattice constant.Only the wave-functions at theΓpoint were con-sidered.Since the self-trapped states are almost completely localized on one bond,they are only weakly aﬀected by the boundary conditions in a64atom supercell.The eﬀect of the k-point sampling was analysed in Ref.[3]where similar calculations for a N impurity were performed using the same supercell.It was found that a more accurate k-point sampling does not change the qualitative physics of the distortion but only increases the self-trapping energy by20%compared to calculations based on theΓ-point only[3].In order to describe a core exciton we adopted the method of Ref.[15],i.e.we generated a norm conserving pseudopotential for an excited carbon atom with one electron in the1s core level andﬁve electrons in the valence2s-2p levels.In our calculations for a valence exciton or biexciton we promoted one or two electrons,respectively,from the highest valence band state to the lowest conduction band state.Clearly,our single-particle approach cannot account for the(small)binding energy of delocalized Wannier excitons.However our approach should account for the most important contribution to the binding energy in the case of localized excitations.Structural relaxation studies were based on the Car-Parrinello(CP) approach[16].We used a standard CP scheme for both the core and the valence exciton, while a modiﬁed CP dynamics,in which the electrons are forced to stay in an arbitrary excited eigenstate[12,17],was necessary to study the BO surfaces corresponding to a valence biexciton.All the calculations were made more eﬃcient by the acceleration methods of Ref.[18].Weﬁrst computed the electronic structure of the core exciton with the atoms in the ideal lattice positions.In this case the excited-core atom induces two defect states in the gap:a non-degenerate level belonging to the A1representation of the T d point group,0.4eV below the conduction band edge,and a3-fold degenerate level with T2character,0.2eV below the conduction band edge.By letting the atomic coordinates free to relax,we found that the absolute minimum of the A1potential energy surface correponds to an asymmetric self-trapping distortion of the lattice similar to that found for the N impurity[3].In particular, the excited-core atom and its nearest-neighbor,labeled a and b,respectively,in Fig.1, move away from each other on the(111)direction.The corresponding displacements from the ideal sites are equal to10.4%and to11.5%of the bond length,respectively,so that the (a,b)-bond is stretched by21.9%.The other atoms move very little:for instance the nearest-neighbor atoms labeled c move by2.4%of the bond length only.This strong localization of the distortion is consistent with the simple scaling arguments discussed above.As a consequence of the atomic relaxation,the non-degenerate level ends up in the gap at1.5eV below the conduction band edge,while the corresponding wavefunction localizes on the stretched bond.The3-fold degenerate level remains close to the conduction band edge,but since the distortion lowers the symmetry from T d to C3v,the3-fold degenerate level splits into a2-fold degenerate E level and a non-degenerate A1level.In Fig.2we report the behavior of the potential energy surfaces corresponding to the ground-state,the A1and the T2core exciton states as a function of the self-trapping dis-tortion.Notice that the distortion gives a total energy gain of0.43eV on the A1potential energy surface.The same distortion causes an increase of the ground-state energy of1.29 eV.Our calculation indicates that the core-exciton behaves like the N impurity[3],support-ing,at least qualitatively,the validity of the equivalent core approximation.The similar behavior of the A1level in the core exciton and in the N impurity case was also pointed out recently in the context of semi-empirical CNDO calculations[9].The diﬀerences between the core exciton and the impurity[3]are only quantitative:in particular,the relaxationenergy and especially the distance of the A1level from the conduction band edge are smaller for the core exciton than for the N impurity.Our results suggest the following interpretation of the experimental data of Refs.[4,8]: (i)During X-ray absorption the atoms are in the ideal lattice positions.Dipole transitions from a1s core level to a A1valence level are forbidden,but transitions to the T2level are allowed.In our calculation the T2level is0.2eV lower than the conduction band edge,in good agreement with the core exciton peak observed in X-ray absorption spectra[4,8].(ii) On the T2BO potential energy surface the lattice undergoes a Jahn-Teller distortion which lowers its energy(see Fig.2).(iii)Since the LO phonon energy in diamond(0.16eV)is comparable to the energy spacing between the A1and the T2surfaces,which is less than 0.2eV after the Jahn-Teller distortion,the probability of a non-adiabatic transition from the T2to the A1surface is large.(iv)On the A1level the system undergoes a strong lattice relaxation resulting in a localization of the exciton on a single bond.(v)The self-trapping distortion induces a Stokes shift in the emitted photon energy.If the atomic relaxation were complete the Stokes shift would be equal to1.9eV,which correponds(see Fig.2) to the energy dissipated in the T2-A1transition(0.2eV),plus the energy gained by self trapping on the A1surface(0.43eV),plus the energy cost of the self-trapping distortion on the ground-state energy surface(1.29eV).The data reported in Ref.[8]show a shift of about1eV in the positions of the peaks associated to the1s core exciton in X-ray absorption and emission spectra.The emission peak is very broad,with a large sideband that corresponds to Stokes shifts of up to5eV.As pointed out in Ref.[8],this large sideband is likely to be the eﬀect of incomplete relaxation. This is to be expected since the core exciton lifetime should be comparable to the phonon period[8].As a consequence,the atomic lattice would be able to perform only a few damped oscillations around the distorted minimum structure during the lifetime of the core exciton.We now present our results for the valence excitations.While in the case of a single exciton the energy is minimum for the undistorted crystalline lattice,in the case of a biex-citon weﬁnd that the energy is minimized in correspondence of a localized distortion of theatomic lattice.This is characterized by a large outward symmetric displacement along the (111)direction of the atoms a and b in Fig.1.As a result the(a,b)-bond is broken since the distance between the atoms a and b is increased by51.2%compared to the crystalline bondlength.This distortion can be viewed as a kind of local graphitization in which the atoms a and b change from fourfold to threefold coordination and the corresponding hy-bridized orbitals change from sp3to sp2character.Again,in agreement with the model based on simple scaling arguments,the distortion is strongly localized on a single bond.As a matter of fact and with reference to the Fig.1,the atoms c and d move by1.2%of the bondlength,the atoms e and f move by2.3%,and the atoms not shown in theﬁgure by less than0.9%.The self-trapping distortion of the biexciton gives rise to two deep levels in the gap: a doubly occupied antibonding level,at1.7eV below the conduction band edge,and an empty bonding level,at1.6eV above the valence band edge.Both states are localized on the broken bond.In Fig.3we show how diﬀerent BO potential energy surfaces behave as a function of the self-trapping distortion of the valence biexciton.In particular,from thisﬁgure we see that,while for the biexciton there is an energy gain of1.74eV in correspondence with the self-trapping distortion,the same distortion has an energy cost of1.49eV for the single exciton,and of4.85eV for the unexcited crystal.We notice that,while DFT-LDA predicts self-trapping for the valence biexciton,it does not do so for the single exciton,in agreement with experiment.Similarly to the case of the core exciton the major experimental consequence of the self-trapping of the valence biexciton is a large Stokes shift in the stimulated-absorption spontaneous-emission cycle between the exciton and the biexciton BO surfaces.As it can be seen from Fig.3,this Stokes shift should be equal to3.23eV,i.e.to the sum of the energy gain of the biexciton(1.74eV)and of the energy cost of the exciton(1.49eV) for the self-trapping relaxation.The fundamental gap of diamond is indirect.Thus the spontaneous decay of a Wannier exciton in an ideal diamond crystal is phonon assistedand the radiative lifetime of the exciton is much longer than in direct gap semiconductors. However,after self-trapping of the biexciton,the translational symmetry is broken and direct spontaneous emission becomes allowed.As a consequence the radiative life time of the self-trapped biexciton is much smaller than that of the Wannier ing the DFT-LDA wavefunctions,we obtained a value of∼7ns for the radiative lifetime of the biexciton within the dipole approximation.This is several orders of magnitude larger than the typical phonon period.Therefore the self-trapping relaxation of the valence biexciton should be completed before the radiative decay.A self-trapped biexciton is a bound state of two excitons strongly localized on a single bond.Thus the formation of self-trapped biexcitons requires a high excitonic density.To realize this condition it is possible either to excite directly bound states of Wannier excitons, or to create a high density electron-hole plasma,e.g.by strong laser irradiation.In the second case many self-trapped biexcitons could be produced.This raises some interesting implications.If many self-trapped biexcitons are created,they could cluster producing a macroscopic graphitization.Moreover,since the process of self-trapping is associated with a relevant energy transfer from the electronic to the ionic degrees of freedom,in a high density electron hole plasma biexcitonic self-trapping could heat the crystal up to the melting point in fractions of a ps,i.e in the characteristic time of ionic relaxation.Interestingly,melting ofa GaAs crystal under high laser irradiation has been observed to occur in fractions of a ps[19].In Ref.[19]this phenomenon has been ascribed to the change in the binding properties due to the electronic excitations.Our study on diamond leads one to speculate that in a sub-picosecond melting experiment self-trapping phenomena could play an important role.In conclusion,we have studied excited-state BO potential energy surfaces of crystalline diamond within DFT-LDA.Our calculation predicts self-trapping of the core exciton and provides a coherent description of the X-ray absorption and emission processes,which com-pares well with the experimental data.Moreover,we also predict self-trapping of the valence biexciton,a process characterized by a large local lattice relaxation.This implies a strong Stokes shift in the stimulated absorption-spontaneous emission cycle of about3eV,whichcould be observed experimentally.It is a pleasure to thank F.Tassone for many useful discussions.We acknowledge support from the Swiss National Science Foundation under grant No.20-39528.93REFERENCES∗Present address:Departement of Physics,University of California,Berkeley CA94720, USA.[1]C.A.J.Ammerlaan,Inst.Phys.Conf.Ser.59,81(1981).[2]R.J.Cook and D.H.Whiﬀen,Proc.Roy.Soc.London A295,99(1966).[3]S.A.Kajihara et al,Phys.Rev.Lett.66,2010(1991).[4]J.F.Morar et al,Phys.Rev.Lett.54,1960(1985).[5]K.A.Jackson and M.R.Pederson,Phys.Rev.Lett.67,2521(1991).[6]J.Nithianandam,Phys.Rev.Lett.69,3108(1992).[7]P.E.Batson,Phys.Rev.Lett.70,1822(1993).[8]Y.Ma et al,Phys.Rev.Lett.71,3725(1993).[9]A.Mainwood and A.M.Stoneham,J.Phys.:Condens.Matter6,4917(1994).[10]R.G.Farrer,Solid State Commun.7,685(1969).[11]W.Hayes and A.M.Stoneham,Defects and defect processes in nonmetallic solids,(Wiley&Sons,New York,1985)pags.29-38.[12]F.Mauri,R.Car,(to be published).[13]The number of equal particles that can be accommodated on one bond of the crystal inthe same quantum state is limited by the Pauli principle.Thus no more than two holes or/and two electrons with opposite spins can be localized on one bond of a sp3bonded semiconductor.[14]G.Bachelet,D.Hamann,and M.Schl¨u ter,Phys.Rev.B26,4199(1982).[15]E.Pehlke and M.Scheﬄer,Phys.Rev.B47,3588(1993).[16]R.Car and M.Parrinello,Phys.Rev.Lett.55,2471(1985).[17]F.Mauri,R.Car and E.Tosatti,Europhys.Lett.24,431(1993).[18]F.Tassone,F.Mauri,and R.Car,Phys.Rev.B50,10561(1994).[19]orkov,I.L.Shumay,W.Rudolph,and T.Schroder,Opt.Lett.16,1013(1991);P.Saeta,J.-K.Wang,Y.Siegal,N.Bloembergen,and E.Mazur,Phys.Rev.Lett.67, 1023(1991);K.Sokolowski-Tinten,H.Schulz,J.Bialkowski,and D.von der Linde, Applied Phys.A53,227(1991).FIGURESFIG.1.Atoms and bonds in the ideal diamond crystal(left panel).Atoms and bonds after the self-trapping distortion associated with the valence biexciton(right panel).In this case the distance between the atoms a and b increases by51.2%.A similar but smaller distortion is associated with the core exciton:in this case the(a,b)distance is increased by21.9%.FIG.2.Total energy vs self-trapping distortion of the core-exciton.Theﬁgure displays the BO potential energy surfaces correponding to the ground-state,the A1,and the T2core exciton states.FIG.3.Total energy as a function of the self-trapping distortion of the biexciton.The BO energy surfaces correponding to the ground state,the valence exciton,and the valence biexciton are shown in theﬁgure.a b ce df(111)ground stateA 1−core excitonT 2−core excitonconduction ideal lattice distorted latticeground statebi−excitonexcitondistorted lattice ideal lattice。

过渡金属掺杂单层MoS2的第一性原理计算

过渡金属掺杂单层MoS2的第一性原理计算牛兴平;张石定;窦立璇【摘要】利用基于密度泛函理论的第一性原理平面波赝势方法分别计算了本征及过渡金属掺杂单层MoS2的晶格参数、电子结构和光学性质.计算结果显示,过渡金属掺杂所引起的晶格畸变与杂质原子的共价半径有联系,但并不完全取决于共价半径的大小.分析能带结构可以看到,Co、Ni、Cu、Tc、Re和W掺杂使能带从直接带隙变成了间接带隙.除了Cr和W以外,其它掺杂体系的禁带区域都出现了数目不等的新能级,这些杂质能级主要由杂质的d、S的3p和Mo的4d轨道组成.掺杂对MoS2的光学性质也产生了相应的影响,使MoS2的静态介电常数、介电函数虚部峰值、折射率和光电导率峰值呈现不同程度的增加.【期刊名称】《功能材料》【年(卷),期】2018(049)007【总页数】5页(P7106-7110)【关键词】过渡金属掺杂;二硫化钼;电子结构;光学性质【作者】牛兴平;张石定;窦立璇【作者单位】安阳工学院数理学院,河南安阳 455000;安阳工学院数理学院,河南安阳 455000;安阳工学院数理学院,河南安阳 455000【正文语种】中文【中图分类】O471.50 引言单层MoS2是一种常见的二维半导体材料[1]，每层MoS2的厚度约为0.65 nm，层与层的间距约为0.615 nm[2]。

每层MoS2由一层Mo原子和上下两层S原子组成，层内的原子以共价键结合，层间的原子以Van der Waals力结合。

由于单层MoS2结构的特殊性而拥有独特的电学和光学特性[3]，使其在润滑剂[4]、催化剂[5]、光电子器件[6]、自旋电子器件[7]、能量存储[8]和场效应管[9]等方面有着潜在的应用价值。

掺杂是半导体器件和集成电路工艺中的一个重要环节，可以通过筛选杂质的种类和调节掺杂的水平来控制半导体的光电特性。

人们对过渡金属掺杂单层MoS2的相关研究已有少量报道，例如吴木生等[10]研究了Cr和W掺杂后电子结构的变化情况，发现W掺杂几乎没有影响，而Cr掺杂后所产生的应力对MoS2的能带结构影响很大。

电气专业英语课后练习翻译

PART1U1T1、In addition to the various power transformers, two special-purpose transformers are used with electric machinery and power systems. The first of these special transformers is a device specially designed to sample a high voltage and produce a low secondary voltage directly proportional to it. Such a transformer is a potential transformer. A power transformer also produces a secondary voltage directly proportional to that the potential transformer is designed to handle only a very small current. The second type of special transformer is a device designed to provide a secondary current much smaller than but directly proportional to its primary current. This device is called a current transformer.除了各种电源变压器、两个专用变压器使用电动机械和电力系统。

第一个特殊变压器是一个高电压设备专门设计的样品和生产较低的二次电压成正比。

这样一个变压器电压互感器。

电力变压器也产生二次电压成正比的电压互感器的设计目的是处理只有一个很小的电流。

First-principles calculation of electronic structures and optical

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density functional theory (DFT) in CASTEP code. The calculated electron structures are found to be in good agreement with the experimental results. On the other hand, the interesting optical properties are calculated and discussed.
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First-principles calculation of electronic structures and optical properties of wurtzite InxAl1ÀxN alloys
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Janus_二维双层MoSSe

第52卷第9期2023年9月人㊀工㊀晶㊀体㊀学㊀报JOURNAL OF SYNTHETIC CRYSTALS Vol.52㊀No.9September,2023Janus 二维双层MoSSe /WSSe 异质结光电性质的第一性原理研究周春起1,张㊀会2,礼楷雨2(1.沈阳大学机械工程学院,沈阳㊀110044;2.沈阳大学师范学院,沈阳㊀110044)摘要:通过第一性原理计算研究了四种二维双层MoSSe /WSSe 范德瓦耳斯异质结的光电性质㊂声子谱表明四种结构具有可靠的热力学稳定性㊂根据堆垛方式的不同,双层MoSSe /WSSe 异质结可以是间接或直接半导体㊂而且,两种Janus 型MoSSe /WSSe 异质结具有1.22和1.88eV 的适中带隙㊁显著的可见光吸收系数㊁跨越了水氧化还原电位的带边位置㊂因此,Janus 型的MoSSe /WSSe 异质结构在光催化水分解领域具有一定的应用前景㊂关键词:第一性原理计算;Janus 二维异质结;光催化水分解;声子色散谱;电子结构;光吸收中图分类号:O482;G312㊀㊀文献标志码:A ㊀㊀文章编号:1000-985X (2023)09-1668-06First-Principles Study on Photoelectric Properties of Janus Two-Dimensional Bilayer MoSSe /WSSe HeterostructuresZHOU Chunqi 1,ZHANG Hui 2,LI Kaiyu 2(1.College of Mechanical Engineering,Shenyang University,Shenyang 110044,China;2.Normal College,Shenyang University,Shenyang 110044,China)Abstract :The photoelectric properties of four two-dimensional bilayer MoSSe /WSSe van der Waals (vdW)heterostructures were investigated by the first-principles calculations.All four heterostructures have been conformed thermodynamic stable by the phonon spectra.Bilayer MoSSe /WSSe heterostructures can be indirect or direct semiconductor,depending on the stacking routes.Moreover,two Janus MoSSe /WSSe heterostructures show the suitable band gap of 1.22and 1.88eV,notable absorption index on the visible light,and band edge positions straddling the water redox potential.Therefore,Janus MoSSe /WSSe heterostructures are expected to have application prospects in the field of photocatalytic water decomposition.Key words :first-principle calculation;Janus two-dimensional heterostructure;photocatalytic water splitting;phonon dispersion spectrum;electronic structure;light absorption ㊀㊀收稿日期:2023-03-06㊀㊀基金项目:辽宁省自然科学基金(2020-MS-306)㊀㊀作者简介:周春起(1995 ),男,黑龙江省人,硕士研究生㊂E-mail:1620222420@ ㊀㊀通信作者:张㊀会,博士,教授㊂E-mail:huizhangsy@0㊀引㊀㊀言二维(two-dimensional,2D)材料(例如黑磷㊁氮化碳㊁过渡金属二卤化物等)因其超大比表面积㊁较好的载流子迁移率和良好的导电性能[1-3],在光催化水分解领域具有非常好的应用前景㊂但是,光催化水分解反应在半导体带隙大小㊁载流子迁移率㊁太阳光吸收效率等诸多方面对光催化剂有着苛刻的要求㊂因此,探索新型的二维光催化材料具有重要的意义㊂垂直堆垛两个相同或不同的材料构成二维双层材料,是设计电子产品的有效方式[4-7]㊂它打破了二维单层材料在器件应用中的局限性,扩展了单一材料体系的光吸收范围,加快了界面处载流子的传输和分离速率[8-10]㊂例如,Wang 等[11]构建了具有较强光吸收系数与光催化性能的范德瓦耳斯异质结MoSe 2/SnSe 2和WSe 2/SnSe 2㊂㊀㊀第9期周春起等:Janus 二维双层MoSSe /WSSe 异质结光电性质的第一性原理研究1669㊀最近,通过垂直堆垛两个Janus 型单层WSSe 而得到WSSe-WSSe 的三种二维双层材料被报道[12],其光吸收性能优异,同时带边电位可跨越水的氧化还原电位,具有出色的光催化水分解能力㊂本工作应用第一性原理计算方法在单层MoSSe 和WSSe 的基础上,通过不同的垂直堆垛方式构建了MoSSe-WSSe 的四种二维双层范德瓦耳斯异质结,并对它们的晶体结构㊁电子性质和光催化性质进行了研究,研究结果表明上述异质结具有可靠的结构稳定性和优越的光催化水分解性能㊂1㊀计算方法本研究基于第一性原理计算,在VASP 软件包中进行[13-14]㊂使用具有PBE 函数的广义梯度近似(GGA)[15]进行结构优化㊂利用HSE06杂化泛函[16]计算了材料的电子性质与光学性质㊂设定HF /DFT 杂化函数计算中的精确交换分数α为默认值0.25㊂用投影缀加波(PAW)[17]赝势处理电子-离子的相互作用㊂为消除层间相互作用,垂直方向设置不小于1.5nm 的真空空间㊂用vaspkit [18]代码处理计算结果㊂为保证总能量在10-5eV 的计算精度,将截止能量设置为600eV㊂用Monkhorst-Pack(MP)方案在布里渊区(BZ)[19]进行K 点取样,网格为14ˑ14ˑ1㊂晶体结构优化收敛标准设置为每个原子上的受力小于0.1eV /nm㊂采用Phonopy 软件包计算材料的声子色散曲线[20-21],并将原子扩胞至2ˑ2ˑ1㊂2㊀结果与讨论2.1㊀晶体结构与稳定性单层MoSSe 或WSSe 在二维空间中具有六边形晶格对称性,每个单元包含三个原子(一个Mo 或W 原子㊁一个S 原子和一个Se 原子)㊂结构优化后单层WSSe 的晶格常数为0.32nm,W S 键长为0.24nm,W Se 键长为0.25nm㊂单层MoSSe 和WSSe 的晶格参数接近㊂以上结果与已有报道非常接近[22-23],表明计算结果是可靠的㊂根据已有报道,与AA 堆垛方式相比,AB 堆垛的双层MoSSe-WSSe 能量更低[24]㊂如图1所示,二维双层材料MoSSe-WSSe 是由单层MoSSe 和WSSe 在垂直方向上通过AB 方式排列堆垛得到的㊂如表1所示,四种异质结构的层间距离为0.31~0.32nm,与双层WSSe 接近[25]㊂本研究通过层间吸附能来验证材料双层结构的稳定性,计算公式为E ad =(E MoSSe +E WSSe )-E BL ,式中E ad ㊁E MoSSe ㊁E WSSe 和E BL 分别代表双层MoSSe-WSSe 的层间吸附能,单层MoSSe㊁单层WSSe 和双层MoSSe-WSSe 的总能量㊂㊂不同堆垛方式构成的双层MoSSe-WSSe 异质结的层间吸附能差别很小,为0.22~0.29eV,而且与双层WSSe 的层间吸附能相当(0.27~0.31eV)[12]㊂层间距离和吸附能表明双层MoSSe-WSSe 异质结层间为范德瓦耳斯结合,而且能够以不同的堆垛方式存在㊂如图2所示,双层MoSSe-WSSe 异质结中,MoSSe 与WSSe 的原子振动没有相互关联,这是由于层间为范德瓦耳斯作用,未形成化学键㊂它们的声子谱中各有18条色散曲线,其中6条声学支与12条光学支皆在零以上分布,进一步表明上述材料具有良好的结构稳定性㊂图1㊀二维双层MoSSe-WSSe 异质结晶体结构侧视图Fig.1㊀Side views of 2D bilayer MoSSe-WSSe heterostructures1670㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第52卷表1㊀二维双层MoSSe-WSSe 异质结的晶格常数㊁层间距(d int )和层间吸附能(E ad )Table 1㊀Lattice constant ,interlayer distance (d int )and interlayer adsorption energy E ad of 2D bilayer MoSSe-WSSe heterostructuresMaterial Lattice constant /nm d int /nm E ad /eV AB 10.3220.3190.22AB 20.3210.3150.26AB 30.3210.3100.29AB 40.3220.3180.23图2㊀二维双层MoSSe-WSSe 异质结的声子谱Fig.2㊀Phonon dispersion spectra of 2D bilayer MoSSe-WSSe heterostructures 2.2㊀电子能带结构与性能本研究利用杂化泛函(HSE06)计算了二维双层MoSSe-WSSe 异质结的电子能带结构㊂如图3所示,AB 2和AB 3的带隙大小分别为1.88和1.89eV,它们的价带顶(valence band maximum,VBM)处于K 点,导带底(conduction band minimum,CBM)则位于K 和Г点之间,因此为间接带隙半导体㊂AB 1和AB 4的带隙值分别为1.22和1.85eV,VBM 与CBM 都在K 点,所以是直接带隙半导体㊂2.3㊀光催化性质材料的带边位置跨越水的氧化还原电位是光催化水裂解反应的必要条件,即CBM 大于-4.44eV(氢H +/H 2的还原电位),而VBM 必须小于-5.67eV(水O 2/H 2O 的氧化电位)[26]㊂由于对称破缺,单层MoSSe 上下表面的静电势不同,可称为Janus 结构㊂如图4所示,AB 1和AB 2异质结上下表面不对称,静电势差(ΔΦ)分别为1.46和1.49eV;而AB 3和AB 4异质结上下表面对称,静电势相等㊂因此,四种MoSSe-WSSe 异质结中,只有AB 1和AB 2为Janus 材料㊂光催化剂带边位置与氧化还原电位的差值可用来描述材料的光催化能力㊂AB 3异质结带边位置与水的氧化还原电位大致相等,催化反应的驱动力较弱;AB 4异质结的VBM 高于水的氧化电位,不具备氧化能力;AB 2异质结由于上下表面静电势的不同,可分别在下表面(WSSe 侧)产生增强的还原反应驱动力,在上表面(MoSSe 侧)产生增强的氧化反应驱动力㊂AB 1可分别在上表面(MoSSe 侧)产生增强的还原反应驱动力,在㊀第9期周春起等:Janus 二维双层MoSSe /WSSe 异质结光电性质的第一性原理研究1671㊀下表面(WSSe 侧)产生较弱的氧化反应驱动力㊂图3㊀二维双层MoSSe-WSSe 异质结的能带结构Fig.3㊀Band structures of 2D bilayer MoSSe-WSSeheterostructures 图4㊀二维双层MoSSe-WSSe 异质结的静电势和带边位置Fig.4㊀Electrostatic potentials and the band edge positions of 2D bilayer MoSSe-WSSe heterostructures1672㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第52卷图5㊀二维双层MoSSe-WSSe 异质结的吸收光谱Fig.5㊀Optical absorption spectra of 2D bilayer MoSSe-WSSe heterostructures 最后,通过材料的光吸收谱探讨光催化材料对可见光的利用效率,光吸收系数通过频率相关的介电函数[27-28]计算㊂ε(ω)=ε1(ω)+i ε2(ω),α(ω)=2(ω)[(ε12(ω)+ε22(ω))-ε1(ω)](1)如图5所示,四种异质结在2.0eV 开始出现明显光吸收,与VBM-CBM 跃迁对应,而更高能量吸收与更高级别的跃迁对应㊂四种MoSSe-WSSe 异质结在可见光范围(1.6~3.2eV)和紫外光范围(>3.2eV)吸收系数能够达到105量级,表明上述四种异质结能够有效吸收太阳光能量㊂3㊀结㊀㊀论本工作在单层二维材料MoSSe 和WSSe 的基础上,构建了四种MoSSe-WSSe 异质结㊂层间吸附能和声子谱表明,MoSSe-WSSe 异质结层间通过范德瓦耳斯吸附,能够稳定存在㊂杂化泛函计算得到四种异质结构的带隙值分别为1.22㊁1.88㊁1.89和1.85eV㊂由于二维双层异质结AB 1和AB 2具有结构不对称性,在其结构内部会产生一个内建电场,在电场的作用下,它的上下表面真空能级之间产生了一个较大的静电势差㊂内建电场和静电势差的存在导致AB 1和AB 2分别在不同的表面跨越了水的氧化还原电位㊂吸收光谱表明,四种异质结具有较强的光吸收能力,因此它们在光催化领域有着较大的潜力㊂参考文献[1]㊀LU Q P,YU Y F,MA Q L,et al.2D transition-metal-dichalcogenide-nanosheet-based composites for photocatalytic and electrocatalytic hydrogenevolution reactions[J].Advanced Materials,2016,28(10):1917-1933.[2]㊀NOVOSELOV K S,FALᶄKO V I,COLOMBO L,et al.A roadmap for graphene[J].Nature,2012,490(7419):192-200.[3]㊀RAN J R,ZHU B C,QIAO S Z.Phosphorene co-catalyst advancing highly efficient visible-light photocatalytic hydrogen production [J].Angewandte Chemie,2017,129(35):10509-10513.[4]㊀LOPEZ-SANCHEZ O,ALARCON LLADO E,KOMAN V,et al.Light generation and harvesting in a van der Waals heterostructure[J].ACSNano,2014,8(3):3042-3048.[5]㊀ROY T,TOSUN M,CAO X,et al.Dual-gated MoS 2/WSe 2van der Waals tunnel diodes and transistors [J].ACS Nano,2015,9(2):2071-2079.[6]㊀WANG Q X,ZHANG Q,LUO X,et al.Optoelectronic properties of a van der waals WS 2monolayer /2D perovskite vertical heterostructure[J].ACS Applied Materials 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应力锥英文解释

1) stress cone应力锥1.Influnce of stucture shape and rubber property on 220 kV cable terminal stress cone;结构形式及材料性能对220kV电缆终端应力锥的影响2.Numerical simulation analysis of 220 kV cable terminal stress cone in force field; 220kV电缆终端应力锥在力场中的数值模拟分析3.AThis paper described the design sequence of the pressing models of the composite stress cone,one important component in heat/cold shrinkable combined terminations used in high voltage XLPE power cables,produced by conduc-tive/insulated silicone rubber.本文阐述了高压电缆冷热缩相结合终端的核心部件-硅橡胶导电/绝缘复合应力锥橡胶件模压成型模具的设计过程,完成了两次成型的分阶段的橡塑模具设计,包括模压工艺参数计算,选择合适压力的模压设备参数等。

2) non-stressed zone无应力锥3) pre fabricated stress cone预制型应力锥4) stress应力1.Influence of annealing condition on the stress impedance of Fe-based amorphous alloy ribbons;退火条件对铁基非晶薄带压应力阻抗效应的影响2.Research on the stress and strain evolution of aluminum alloy hot forging die;铝合金热锻模具结构中的应力应变演变过程分析3.Analysis on Stress and Strain Behavior of Spherical Vessel of Functionally Graded Material under Creep Condition;蠕变条件下梯度材料球罐应力应变行为分析5) strain应力1.Research progress of the influences of strain on perovskite type manganite compounds;应力对钙钛矿型锰酸盐化合物影响的研究进展2.New development in simultaneous discriminating measurement of temperature and strain by using fibre grating sensing technology;光纤光栅温度应力同时区分测量技术的新进展3.First principles study of electronic structure of ZnO under strain;应力条件下ZnO电子结构的第一性原理研究6) stresses应力1.Determining Stresses and Deflections in the Flat Spring Assembly under Complex Loads;纵横弯曲状态下组合直片簧的应力与变形2.Numerical Analysis of Residual Stresses and Fracture Forms in C/SiC Composite Joints;C/SiC复合材料连接接头应力与破坏形式数值分析3.Because of high temperature and high pressure in the production,great deal of stresses exist in the interface of diamond layer and Tungsten carbide substrate,and also exist in the inner bug of diamond.表明:聚晶金刚石复合片在聚晶金刚石层内存在着宏观应力和微观应力;聚晶金刚石复合片表面应力大小可以反映聚晶金刚石层的应力存在状况;聚晶金刚石复合片残余应力的大小与XRD图谱的斜率成正比,因此XRD方法可以用于聚晶金刚石复合片应力的表征。

天津大学光学考研复习辅导资料及导师分数线信息

天津大学光学考研复习辅导资料及导师分数线信息天津大学光学考研科目包括政治、外语以及普通物理、量子力学。

研究方向主要包括生物医学光子学；现代光学测试学与图像处理；量子光学与量子通讯；导波光学与集成光子学；衍射光学及其应用。

考生可根据自己的兴趣选择具体的研究方向。

专业代码、名称及研究方向考试科目备注复试科目：光学070300光学①101思想政治理论②201英语一③717普通物理④837量子力学天津大学光学近两年考研录取情况院（系、所）专业报考人数录取人数理学院（2012年）光学10 3理学院（2013年）光学11 6天津大学理学院光学2012年的报考人数为10人，录取人数为3人，2013年的报考人数为11人，录取人数为6人。

由真题可以发现，现在考点涉及的广度和深度不断扩宽和加深。

由天津考研网签约的天津大学在读本硕博团队搜集整理了天津大学理学院光学考研全套复习资料，帮助考生梳理知识点并构建知识框架。

真题解析部分将真题按照知识点划分，条理清晰的呈现在同学们眼前。

然后根据各个考点的近几年真题解析，让同学对热点、难点了然于胸。

只有做到了对真题规律和趋势的把握，8—10月底的提高复习才能有的放矢、事半功倍！天津大学理学院光学考研导师信息吴萍纵向课题经费课题名称Sn-Zn基和Sn-Cu-Bi无铅焊球凸点互连电迁移行为及其失效机理研究2011-01-01--2013-12-31 负责人:吴萍科技计划:国家自然科学基金拨款单位:国家基金委合同经费:37课题名称纳米结构无铅焊球的制备及其在电子封装技术中的应用2006-04-01--2009-12-31 负责人:吴萍科技计划:天津市自然科学基金重点项目拨款单位:天津市科委合同经费:20课题名称均匀颗粒成型法制备Sn-3.0Ag-0.5Cu、Sn-8Zn-3Bi无铅焊球的热力学机理研究2007-01-01--2009-12-31 负责人:吴萍科技计划:国家自然科学基金拨款单位:国家基金委合同经费:29课题名称新型无铅复合焊球的研制及其电迁移失效机理研究2011-04-01--2014-03-31 负责人:吴萍科技计划:天津市自然科学基金重点项目拨款单位:天津市科委合同经费:20期刊、会议论文吴萍、周伟、刘立娟、李宝凌、张洪波均匀液滴喷射三维快速成型方法与装置吴萍、周伟、刘立娟、李宝凌、张洪波均匀液滴喷射三维快速成型方法与装置吴萍、周伟、刘立娟、李宝凌、王艺自动焊球封装植球方法与装置吴萍、周伟、刘立娟、李宝凌、徐志伟一种二次库仑分裂制备纳米颗粒的装置米文博人才称号教育部新世纪人才、天津市131人才计划第一层次、天津大学北洋青年学者纵向课题经费课题名称反应溅射Fe4N薄膜的自旋极化率、自旋注入和磁电阻效应研究2012-01-01--2015-12-31 负责人:米文博科技计划:国家自然科学基金面上项目拨款单位:国家自然科学基金委员会合同经费:60课题名称粒度可控、取向生长的L10结构FePt-C基二维颗粒膜的微结构和磁性2008-01-01--2010-12-31 负责人:米文博科技计划:国家自然科学基金青年基金拨款单位:国家自然科学基金委员会合同经费:24课题名称有序化L10结构FePt-C基颗粒膜的制备、结构与磁性2008-04-01--2011-03-31 负责人:米文博科技计划:天津市自然科学基金面上项目拨款单位:天津市科委合同经费:10课题名称Fe4N/半导体异质结构的自旋相关电子输运特性2013-01-01--2015-12-31 负责人:米文博科技计划:教育部留学回国人员启动基金项目拨款单位:教育部合同经费:3课题名称反应溅射Fe4N薄膜的自旋相关电子输运特性研究2012-04-01--2015-03-31 负责人:米文博科技计划:天津市自然科学基金重点项目拨款单位:天津市科委合同经费:20课题名称柔性有机自旋阀的磁电阻效应研究2014-01-01--2016-12-31 负责人:米文博科技计划:教育部新世纪人才计划拨款单位:教育部合同经费:50 课题名称磁性金属—氧化物半导体复合薄膜的磁电阻效应研究2008-01-01--2010-12-31 负责人:米文博科技计划:教育部博士点基金新教师基金拨款单位:教育部合同经费:3.6期刊、会议论文李滋润、米文博、王晓姹、张西祥Interfacial Exchange Coupling Induced Anomalous Anisotropic Magnetoresistance in Epitaxial γ′-Fe4N/CoN Bilayers ACS Appl. Mater.& Interfacesnull李滋润、封秀平、王晓姹、米文博Anisotropic Magnetoresistance in Facing-Target Reactively Sputtered Epitaxial γ'-Fe4N Films Mater. Res. Bull.null王俊宝、米文博、王来森、彭栋梁Interfacial scattering induced enhancement of anomalous Hall effect in uniform Fe nanocluster assembled films Europhys. Lett.null 李滋润、米文博、王晓姹、白海力Inversion of Exchange Bias and Complex Magnetization Reversal in Full-Nitride Epitaxial γ′-Fe4N/CoN Bilayers J. Magn. Magn. Mater.null 冯楠、米文博、王晓姹、白海力First-Principles Study on The Interfacial Magnetic and Electronic Properties of Fe4N(001)/Si and Fe4N(111)/Graphene Bilayers Comput. Mater. Sci.null冯楠、米文博、王晓姹、白海力The Magnetism of Fe4N/Oxides (MgO, BaTiO3, BiFeO3) Interfaces From First-Principles Calculations RSC Advancesnull张雪静、米文博、王晓姹、白海力First-Principles Prediction of Electronic Structure and Magnetic Ordering of Rare-earth Metals Doped ZnO J. Alloys Compd.null王俊宝、米文博、王来森、彭栋梁Enhanced anomalous Hall effect in Fe nanocluster assembled thin films Phys. Chem. Chem. Phys.null冯楠、米文博、程迎春、郭载兵、Udo Schwingenschl？gl、白海力Magnetism by Interfacial Hybridization and p-type Doping of MoS2 in Fe4N/MoS2 Superlattices: A First Principles Study ACS Appl. Mater. & Interfaces null张雪静、米文博、王晓姹、程迎春、Udo Schwingenschl？gl The Interface between Gd andMonolayer MoS2: A First-Principles Study Scientific Reportsnull冯楠、米文博、程迎春、郭载兵、Udo Schwingenschl？gl、白海力First Principles Prediction of the Magnetic Properties of Fe-X6 (X=S, C, N, O, F) Doped Monolayer MoS2 Scientific Reportsnull张雪静、米文博、郭载兵、程迎春、陈贵峰、白海力Role of Anion Doping on Electronic Structure and Magnetism of GdN by First Principles Calculations RSC Advancesnull 米文博、郭载兵、段秀峰、张雪静、白海力Large Negative Magnetoresistance in Reactive Sputtered Polycrystalline GdNx Films Appl. Phys. Lett. null米文博、杨华、程迎春、陈贵峰、白海力Magnetic and Electronic Properties ofFe3O4/Graphene Heterostructures: First Principles Perspective J. Appl. Phys.null段秀峰、米文博、郭载兵、白海力Magnetoresistance and Anomalous Hall Effect of Reactive Sputtered Polycrystalline Ti1？xCrxN Films Thin Solid Filmsnull米文博、郭载兵、封秀平、白海力Reactively Sputtered Epitaxial γ'-Fe4N Films: Surface Morphology, Microstructure, Magnetic and Electrical Transport Propertie Acta Materialianull段秀峰、米文博、郭载兵、白海力 A Comparative Study of Transport Properties in Polycrystalline and Epitaxial Chromium Nitride Films J. Appl. Phys.null杨华、程迎春、陈贵峰、米文博、白海力Magnetic and Electronic Properties of Cu1-xFexO from First Principles Calculations RSC Advancesnull米文博、郭载兵、王清晓、杨洋、白海力Charge Ordering in Reactive Sputtered (100) and(111) Oriented Epitaxial Fe3O4 Films Scripta Materialianull杨华、金朝、米文博、白海力Electronic and Magnetic Structure of Fe3O4/BiFeO3 Multiferroic Superlattices: First Principles Calculations J. Appl. Phys.null杨华、米文博、白海力、程迎春Electronic and Optical Properties of New Multifunctional Materials via Half-substituted HEMATITE: First Principles Calculatio RSC Advancesnull 王晓姹、马力、米文博Positive Magnetoresistance in Amorphous Ni-CNx/p-Si Heterostructure Appl. Phys. Exp.null段秀峰、米文博、郭载兵、白海力Magnetic and spin-dependent transport properties of reactive sputtered epitaxial Ti1？xCrxN films Acta Materialianull米文博、杨华、程迎春、白海力Ferromagnetic half-metallic characteristic in bulkNi0.5M0.5O (M=Cu, Zn and Cd): A GGA+U study Solid State Commun.null米文博、封秀平、段秀峰、杨华、李岩、白海力Microstructure, magnetic and electrical transport properties of polycrystalline γ'-Fe4N films Thin Solid Filmsnull米文博, 封秀平, 白海力Magnetic properties and Hall effect of reactive sputtered iron nitride nanocrystalline films Journal of Magnetism and Magnetic Materialsnull米文博, 金晶, 白海力Enhanced magnetic properties of annealed Fe48Pt52-C composite films by N incorporation Physica Status Solidi Anull封秀平, 米文博, 白海力Polycrystalline iron nitride films fabricated by reactivefacing-target sputtering: structure, magnetic and electrical transport properties Journal of Applied Physicsnull米文博, 何琲, 李志青, 吴萍, 姜恩永, 白海力Structure and magnetic properties ofN-doped Fe-C granular films Journal of Physics D: Applied Physicsnull省部级以上获奖白海力、米文博、王晓姹、刘宜伟、姜恩永铁磁性复合薄膜的制备、结构和物性研究天津市自然科学奖二等奖2013-03-26知识产权米文博, 叶天宇, 白海力铬掺杂氮化钛磁性半导体多晶薄膜的制备方法中国1米文博, 白海力具有大的霍尔效应的氮化铁薄膜的制备方法中国2米文博，段秀峰，白海力一种具有大磁电阻效应的GdN薄膜及制备方法中国5米文博，金朝，白海力具有电流调控磁电阻效应的Fe3O4/p-Si结构及制备方法中国4 米文博，段秀峰，白海力具有低温磁电阻效应的外延Ti0.53Cr0.47N薄膜材料及制备方法中国3学术专著(米文博王晓姹), 自旋电子学基础, 天津大学出版社2013-05-01戴伍圣纵向课题经费课题名称计算有效作用量、真空能和计数函数的新途径及其在量子场论、统计力学和谱问题中的应用2011-01-01--2013-12-01 负责人:戴伍圣科技计划:国家自然科学基金委拨款单位:国家自然科学基金委合同经费:28课题名称自引力天体物理系统的非广延统计力学研究2007-01-01--2009-12-31负责人:杜九林科技计划:国家自然科学基金委拨款单位:国家自然科学基金委合同经费:28课题名称量子纠缠/ 贝尔不等式及其相关2007-01-01--2009-12-31 负责人:陈景灵科技计划:国家自然科学基金委拨款单位:国家自然科学基金委合同经费:20期刊、会议论文刘彤，李文都，戴伍圣Scattering theory without large-distance asymptotics JHEPnull 戴伍圣，谢汨Calculating statistical distributions from operator relations The statistical distributions of various intermediate statisti Annals of Physicsnull庞海，戴伍圣，谢汨Relation between heat kernel method and scattering spectral method ull邱荣涛，戴伍圣，谢汨Mean first-passage time of quantum transition processes Physica.Anull刘彤，张萍，戴伍圣，谢汨An intermediate distribution between Gaussian and Cauchy distributions Physics Anull庞海, 戴伍圣, 谢汨The pressure exerted by a confined ideal gas J. Phys. Anull本文内容摘自《天津大学理学院普通物理+量子力学考研红宝书》，更多考研资料可登陆网站下载！。

First-principles Calculations of the Electronic Structure and Spectra of Strongly Correlate

a rX iv:c ond-ma t/974231v1[c ond-m at.str-el]28A pr1997First-principles calculations of the electronic structure and spectra of strongly correlated systems:dynamical mean-ﬁeld theory V.I.Anisimov,A.I.Poteryaev,M.A.Korotin,A.O.Anokhin Institute of Metal Physics,Ekaterinburg,GSP-170,Russia G.Kotliar Serin Physics Laboratory,Rutgers University,Piscataway,New Jersey 08854,USA Abstract A recently developed dynamical mean-ﬁeld theory in the iterated per-turbation theory approximation was used as a basis for construction of the ”ﬁrst principles”calculation scheme for investigating electronic struc-ture of strongly correlated electron systems.This scheme is based on Local Density Approximation (LDA)in the framework of the Linearized Muﬃn-Tin-Orbitals (LMTO)method.The classical example of the doped Mott-insulator La 1−x Sr x TiO 3was studied by the new method and the results showed qualitative improvement in agreement with experimental photoemission spectra.1Introduction The accurate calculation of the electronic structure of materials starting from ﬁrst principles is a challenging problem in condensed matter science since un-fortunately,except for small molecules,it is impossible to solve many-electron problem without severe approximations.For materials where the kinetic energy of the electrons is more important than the Coulomb interactions,the most successful ﬁrst principles method is the Density Functional theory (DFT)within the Local (Spin-)Density Ap-proximation (L(S)DA)[1],where the many-body problem is mapped into a non-interacting system with a one-electron exchange-correlation potential approxi-mated by that of the homogeneous electron gas.It is by now,generally accepted that the spin density functional theory in the local approximation is a reliable starting point for ﬁrst principle calculations1of material properties of weakly correlated solids(For a review see[2]).The situation is very diﬀerent when we consider more strongly correlated materials, (systems containing f and d electrons).In a very simpliﬁed view LDA can be regarded as a Hartree-Fock approximation with orbital-independent(averaged) one-electron potential.This approximation is very crude for strongly correlated systems,where the on-cite Coulomb interaction between d-(or f-)electrons of transition metal(or rare-earth metal)ions(Coulomb parameter U)is strong enough to overcome kinetic energy which is of the order of band width W.In the result LDA gives qualitatively wrong answer even for such simple systems as Mott insulators with integer number of electrons per cite(so-called”undoped Mott insulators”).For example insulators CoO and La2CuO4are predicted to be metallic by LDA.The search for a”ﬁrst principle”computational scheme of physical proper-ties of strongly correlated electron systems which is as successful as the LDA in weakly correlated systems,is highly desirable given the considerable impor-tance of this class of materials and is a subject of intensive current research. Notable examples ofﬁrst principle schemes that have been applied to srongly correlated electron systems are the LDA+U method[3]which is akin to orbital-spin-unrestricted Hartree-Fock method using a basis of LDA wave functions,ab initio unrestricted Hartree Fock calculations[4]and the use of constrained LDA to derive model parameters of model hamiltonians which are then treated by exact diagonalization of small clusters or other approximations[5].Many interesting eﬀects,such as orbital and charge ordering in transition metal compounds were successfully described by LDA+U method[6].However for strongly correlated metals Hartree-Fock approximation is too crude and more sophisticated approaches are needed.Recently the dynamical mean-ﬁeld theory was developed[7]which is based on the mapping of lattice models onto quantum impurity models subject to a self-consistency condition.The resulting impurity model can be solved by var-ious approaches(Quantum Monte Carlo,exact diagonalization)but the most promising for the possible use in”realistic”calculation scheme is Iterated Per-turbation Theory(IPT)approximation,which was proved to give results in a good agreement with more rigorous methods.This paper is theﬁrst in a series where we plan to integrate recent devel-ompements of the dynamical meanﬁeld approach with state of the art band structure calculation techniques to generate an”ab initio”scheme for the cal-culation of the electronic structure of correlated solids.For a review of the historical development of the dynamical meanﬁeld approach in its various im-plementations see ref[7].In this paper we implement the dynamical mean-ﬁeld theory in the iterated perturbation theory approximation,and carry out the band structure calculations using a LMTO basis.The calculational scheme is described in section2.We present results obtained applying this method to La1−x Sr x TiO3which is a classical example of strongly correlated metal.22The calculation schemeIn order to be able to implement the achievements of Hubbard model theory to LDA one needs the method which could be mapped on tight-binding model.The Linearized Muﬃn-Tin Orbitals(LMTO)method in orthogonal approximation[8]can be naturally presented as tight-binding calculation scheme (in real space representation):H LMT O= ilm,jl′m′,σ(δilm,jl′m′ǫil n ilmσ+t ilm,jl′m′ c†ilmσ c jl′m′σ)(1)(i-site index,lm-orbital indexes).As we have mentioned above,LDA one-electron potential is orbital-inde-pendent and Coulomb interaction between d-electrons is taken into account in this potential in an averaged way.In order to generalize this Hamiltonian by including Coulomb correlations,one must add interaction term:1H int=Un d(n d−1)(3)2(n d= mσn mσtotal number of d-electrons).3In LDA-Hamiltonianǫd has a meaning of the LDA-one-electron eigenvalue for d-orbitals.It is known that in LDA eigenvalue is the derivative of the total energy over the occupancy of the orbital:ǫd=ddn d (E LDA−E Coul)=ǫd−U(n d−12)(7)(q is an index of the atom in the elementary unit cell).In the dynamical mean-ﬁeld theory the eﬀect of Coulomb correlation is de-scribed by self-energy operator in local approximation.The Green function is:G qlm,q′l′m′(iω)=1The chemical potential of the eﬀective medium µis varied to satisfy Luttinger theorem condition:1d(iωn)Σ(iωn)=0(11)In iterated perturbation theory approximation the anzatz for the self-energy is based on the second order perturbation theory term calculated with”bath”Green function G0:Σ0(iωs)=−(N−1)U21kT,Matsubara frequenciesωs=(2s+1)πβ;s,n integer numbers.The termΣ0is renormalized to insure correct atomic limit:Σ(iω)=Un(N−1)+AΣ0(iω)β iωn e iωn0+G(iωn)),B=U[1−(N−1)n]−µ+ µn0(1−n0)(15)n0=1iω+µ−∆(iω)+δµ+n(N−1)β iωn e iωn0+G CP A(iωn)(18) D[n]=n iωn e iωn0+1energy to time variables and back:G0(τ)=1V Bd k[z−H(k,z)]−1(24)After diagonalization,H(k,z)matrix can be expressed through diagonal matrix of its eigenvalues D(k,z)and eigenvectors matrix U(k,z):H(k,z)=U(k,z)D(k,z)U−1(k,z)(25) and Green function:G(z)=1V Bd k U in(k,z)U−1nj(k,z)V Bvd kU in(k,z)U−1nj(k,z)V B(28)6v is tetrahedron volumer n i=(z−D n(k i,z))2k(=j)(D n(k k,z)−D n(k j,z))ln[(z−D n(k j,z))/(z−D n(k i,z)]1+a2(z−z2)1(30)where the coeﬃcients a i are to be determined so that:C M(z i)=u i,i=1,...,M(31) The coeﬃcients a i are then given by the recursion:a i=g i(z i),g1(z i)=u i,i=1,...,M(32)g p(z)=g p−1(z p−1)−g p−1(z)3ResultsWe have applied the above described calculation scheme to the doped Mott insulator La1−x Sr x TiO3is a Pauli-paramagnetic metal at room tem-perature and below T N=125K antiferromagnetic insulator with a very small gap value(0.2eV).Doping by a very small value of Sr(few percent)leads to the transition to paramagnetic metal with a large eﬀective mass.As photoemission spectra of this system also show strong deviation from the noninteracting elec-trons picture,La1−x Sr x TiO3is regarded as an example of strongly correlated metal.The crystal structure of LaTiO3is slightly distorted cubic perovskite.The Ti ions have octahedral coordination of oxygen ions and t2g-e g crystalﬁeld splitting of d-shell is strong enough to survive in solid.On Fig.1the total and partial DOS of paramagnetic LaTiO3are presented as obtained in LDA calculations (LMTO method).On3eV above O2p-band there is Ti-3d-band splitted on t2g and e g subbands which are well separated from each other.Ti4+-ions have d1 conﬁguration and t2g band is1/6ﬁlled.As only t2g band is partiallyﬁlled and e g band is completely empty,it is reasonable to consider Coulomb correlations between t2g−electrons only and degeneracy factor N in Eq.(12)is equal6.The value of Coulomb parameter U was calculated by the supercell procedure[9]regarding only t2g−electrons as localized ones and allowing e g−electrons participate in the screening.This cal-culation resulted in a value3eV.As the localization must lead to the energy gap between electrons with the same spin,the eﬀective Coulomb interaction will be reduced by the value of exchange parameter J=1eV.So we have used eﬀective Coulomb parameter U eff=2eV.The results of the calculation for x=0.06(dop-ing by Sr was immitated by the decreasing on x the total number of electrons) are presented in the form of the t2g-DOS on Fig.2.Its general form is the same as for model calculations:strong quasiparticle peak on the Fermi energy and incoherent subbands below and above it corresponding to the lower and upper Hubbard bands.The appearance of the incoherent lower Hubbard band in our DOS leads to qualitatively better agreement with photoemission spectra.On Fig.3the exper-imental XPS for La1−x Sr x TiO3(x=0.06)[12]is presented with non-interacting (LDA)and interacting(IPT)occupied DOS broadened to imitate experimental resolution.The main correlation eﬀect:simultaneous presence of coherent and incoherent band in XPS is successfully reproduced in IPT calculation.However, as one can see,IPT overestimates the strength of the coherent subband.4ConclusionsIn this publication we described how one can interface methods for realistic band structure calculations with the recently developed dynamical meanﬁeld8technique to obtain a fully”ab initio”method for calculating the electronic spectra of solids.With respect to earlier calculations,this work introduces several method-ological advances:the dynamical meanﬁeld equations are incorporated into a realistic electronic structure calculation scheme,with parameters obtained from aﬁrst principle calculation and with the realistic orbital degeneracy of the compound.To check our method we applied to doped titanates for which a large body of model calculation studies using dynamical meanﬁeld theory exists.There results are very encouraging considering the experimental uncertainties of the analysis of the photoemission spectra of these compounds.We have used two relative accurate(but still approximate)methods for the solution of the band structure aspect and the correlation aspects of this problem:the LMTO in the ASA approximation and the IPT approximation. In principle,one can use other techniques for handling these two aspects of the problem and further application to more complicated materials are necessary to determine the degree of quantitative accuracy of the method.9References[1]Hohenberg P.and Kohn W.,Phys.Rev.B136,864(1964);Kohn W.andSham L.J.,ibid.140,A1133(1965)[2]R.O.Jones,O.Gunnarsson,Reviews of Modern Physics,v61,689(1989)[3]Anisimov V.I.,Zaanen J.and Andersen O.K.,Phys.Rev.B44,943(1991)[4]S.Massida,M.Posternak, A.Baldareschi,Phys.Rev.B46,11705(1992);M.D.Towler,N.L.Allan,N.M.Harrison,V.R.Sunders,W.C.Mackrodt,E.Apra,Phys.Rev.B50,5041(1994);[5]M.S.Hybertsen,M.Schlueter,N.Christensen,Phys.Rev.B39,9028(1989);[6]Anisimov V.I.,Aryasetiawan F.and Lichtenstein A.I.,J.Phys.:Condens.Matter9,767(1997)[7]Georges A.,Kotliar G.,Krauth W.and Rozenberg M.J.,Reviews of ModernPhysics,v68,n.1,13(1996)[8]O.K.Andersen,Phys.Rev.B12,3060(1975);Gunnarsson O.,Jepsen O.andAndersen O.K.,Phys.Rev.B27,7144(1983)[9]Anisimov V.I.and Gunnarsson O.,Phys.Rev.B43,7570(1991)[10]Lambin Ph.and Vigneron J.P.,Phys.Rev.B29,3430(1984)[11]Vidberg H.J.and Serene J.W.,Journal of Low Temperature Physics,v29,179(1977)[12]A.Fujimori,I.Hase,H.Namatame,Y.Fujishima,Y.Tokura,H.Eisaki,S.Uchida,K.Takegahara,F.M.F de Groot,Phys.Rev.Lett.69,1796(1992).(Actually in this article the chemical formula of the sample was LaTiO3.03, but the excess of oxygen produce6%holes which is equivalent to doping of 6%Sr).105Figure captionsFig.1.Noninteracting(U=0)total and partial density of states(DOS)for LaTiO3.Fig.2.Partial(t2g)DOS obtained in IPT calculations in comparison with noninteracting DOS.Fig.3.Experimental and theoretical photoemission spectra of La1−x Sr x TiO3 (x=0.06).11)LJ 7L G H J '26 V W D W H H 9 D W R P (QHUJ\ H97L G W J7RWDO /D7L2 '26 V W D W H H 9 F H O O3HUWXUEDWHG)LJ'26 V W D W H V H 9 (QHUJ\ H98QSHUWXUEDWHG,Q W H Q V L W \ H 9(QHUJ\ H9。

Mn掺杂浓度对Mn-N共掺ZnO电子结构及磁性的影响

Mn掺杂浓度对Mn-N共掺ZnO电子结构及磁性的影响秦盈星;符斯列;蒋联娇;丁罗城;吴先球【摘要】The formation energy,energy gap structure,density of states and ferromagnetism of ZnO single-doped Mn and Mn-N co-doped dopant system at 1 ∶ 1 and 2 ∶ 1 were calculated respectively using first-principles super-soft pseudopotential method.The calculated results show that the single doped Mncan not obtain the stable ZnO doping system,but Mn-N co-dopedcan form p-type pared by Mn-N co-doped (Mn doping concentration of 6.25％),Mn-N co-dop ed dopant system at 2 ∶ 1 (Mn doping concentration of 12.5％) has lower formation energy and a higher chemical stability.Further studies on the magnetic properties of ZnO doping system show that the single-doped Mn and Mn-N co-doped both make the ZnO system ferromagnetism,and its magnetic properties mainly come from Mn 3d electrons.The increase of Mn doping concentration in Mn-N co-doped dopant system at 2 ∶ 1 leads to the increase of the total magnetic moment and the enhancement of ferromagnetism.%采用第一性原理的超软赝势法,分别计算单掺杂Mn、Mn-N按1∶1和2∶1共掺杂ZnO掺杂体系的形成能、能带结构、态密度以及铁磁性.计算结果表明,单掺Mn并不能得到稳定的ZnO,Mn-N共掺会形成p型ZnO.相对Mn-N以1∶1共掺(Mn掺杂浓度6.25％),Mn-N以2∶1共掺(Mn掺杂浓度12.5％)具有更低的形成能,更高的化学稳定性.进一步对ZnO掺杂体系的磁性研究表明,单掺Mn及Mn-N共掺均使ZnO 体系呈现铁磁性,其磁性主要来源于Mn3d态电子;在Mn-N以2∶1共掺ZnO体系中,由于Mn掺杂浓度提高,导致总磁矩增加,铁磁性增强明显.【期刊名称】《功能材料》【年(卷),期】2017(048)010【总页数】5页(P10094-10098)【关键词】ZnO;Mn-N共掺杂;形成能;铁磁性【作者】秦盈星;符斯列;蒋联娇;丁罗城;吴先球【作者单位】华南师范大学物理与电信工程学院,广东省量子调控工程与材料重点实验室,广州510006;华南师范大学物理与电信工程学院,广东省量子调控工程与材料重点实验室,广州510006;华南师范大学物理与电信工程学院,广东省量子调控工程与材料重点实验室,广州510006;华南师范大学物理与电信工程学院,广东省量子调控工程与材料重点实验室,广州510006;华南师范大学物理与电信工程学院,广东省量子调控工程与材料重点实验室,广州510006【正文语种】中文【中图分类】O469纤锌矿型ZnO是一种Ⅱ-Ⅵ宽禁带直接带隙半导体材料，室温下禁带宽度约为3.37 eV，激子束缚能为60 meV，高温下热激发的离化能约为26 meV[1]。

扶手椅型石墨烯纳米带吸附钛原子链的电子结构和磁性

扶手椅型石墨烯纳米带吸附钛原子链的电子结构和磁性孙凯刚;解忧;周安宁;陈立勇;庞绍芳;张建民【摘要】采用基于密度泛函理论的第一性原理方法,研究了扶手椅型石墨烯纳米带(10G、11G、12G和13G)吸附zigzag型Ti原子链的几何结构、电子性质和磁性.结果表明,zigzag型Ti原子链可以稳定吸附在石墨烯纳米带表面.Ti原子链吸附在纳米带的边缘洞位(10G-1、11G-1、12G-1和13G-1)时较为稳定,且稳定程度随着纳米带宽度的增加而增加.Ti原子链吸附在不同宽度石墨烯纳米带的不同位置,呈现不同的电子结构特性.其中,10G-1、10G-2和11G-2的吸附体系表现出半金属特性,其余吸附体系都为金属性质.同时,石墨烯纳米带吸附Ti原子链的体系具有磁性,其磁性主要来源于Ti原子.当Ti原子链吸附在纳米带边缘洞位时,zigzag原子链上A类Ti原子的磁矩总是小于B类Ti原子的磁矩;随着Ti原子链移向纳米带中心,两类Ti原子的磁矩趋于相等.研究结果揭示,通过吸附zigzag型Ti原子链,可以有效调控石墨烯纳米带的电子结构与磁性质.【期刊名称】《陕西师范大学学报（自然科学版）》【年(卷),期】2016(044)002【总页数】6页(P27-32)【关键词】石墨烯纳米带;原子链;电子结构;磁性;密度泛函理论【作者】孙凯刚;解忧;周安宁;陈立勇;庞绍芳;张建民【作者单位】西安科技大学理学院,陕西西安710054;西安科技大学理学院,陕西西安710054;西安科技大学化学与化工学院,陕西西安710054;西安科技大学理学院,陕西西安710054;西安科技大学理学院,陕西西安710054;陕西师范大学物理学与信息技术学院,陕西西安710119【正文语种】中文【中图分类】O469PACS: 73.22.Pr, 75.75.-c, 61.48.Gh, 31.15.E-石墨烯(graphene)[1]自从在实验上被成功制备以来，就以其新奇而丰富的物理化学性质引起了科技工作者的广泛关注。

Sr_(2)MoBO_(6)(B=Os、Re、W)的电子结构与光学性质的第一性原理

渊区内选取 1 000 个 k 点。自洽计算的能量收敛判据为 10 - 5 Ry / f. u. 。
为了准确地描述 d 电子的库伦关联作用,计算采用“ 旋转不变” 法对 Mo 4d 和 B 5d 轨道进行了“ + U” 计
算 [15] 。通过对一系列合理 U 值的测试( Mo:2 ~ 6 eV;B:1 ~ 4 eV) ,发现得到的主要结论是一致的。因此,选
质进行理论计算,并分析能带结构与介电函数、吸收系数之间的联系,以期得到在可见光波段具有宽光谱、强
吸收的双钙钛矿材料。
1 计算方法
本文采用 VASP 软件包 [16-17] 对 Sr2 MoBO6 ( B = Os、Re、W) 进行晶体结构优化。其中电子间的交换关联
能由广义梯度近似( GGA) 的 PBE 泛函 [18] 处理,电子与离子间的相互作用由投影缀加平面波( PAW) [19] 方法
( College of Science, Qiqihar University, Qiqihar 161000, China)
Abstract:Double perovskite oxides Sr2 MoBO6 ( B = Os,Re,W) have been predicted to be half metals with high magnetic
2 结果与讨论
2. 1 晶体结构与电子结构
Sr 2 MoBO 6 ( B = Os、 Re、 W) 的晶体结构均为立
方结构, 空间群为 Fm-3 m ( No. 225 ) , 晶格常数约
为0 . 8 nm,结构示意图如图 1 所示。三种晶体的
以发现,三种 Mo 基化合物的磁转变温度均高于室温,且 Sr2 MoWO6 和 Sr2 MoOsO6 展现出半金属性质。另外,

2015年度中国有色金属科技论文奖评选结果

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Al-Bogami，Deia Abd El-Hady，Jun Lu，Khalil Amine北京理工大学材料学院北京理工大学Kinetics of rare earth pre-loading with 2-ethylhexyl phosphoric acid mono 2-ethylhexyl ester [HEH(EHP)]using rare earth carbonates Separation and PurificationTechnology王良士，黄小卫，于瀛，龙志奇北京有色金属研究总院北京有色金属研究总院Effect of samarium on microstructure and corrosion resistance of aged as-cast AZ92 magnesium alloy 稀土学报（英文版）吴道高，颜世宏，王志强，苗睿瑛，张小伟，陈德宏北京有色金属研究总院有研稀土新材料股份有限公司Synthesis of lanthanum oxide nanosheets by a greencarbonation process Chinese Science Bulletin（2015更名为ScienceBulletin）肖燕飞，冯宗玉，黄小卫，黄莉，龙志奇，王强，侯永可北京有色金属研究总院北京有色金属研究总院Impurities especially titanium in the rare earth metalgadolinium —before and after solid stateelectrotransport Journal of Rare Earths苗睿瑛，张小伟，朱琼，张志琦，王志强，颜世宏，陈德宏，周林，李宗安北京有色金属研究总院北京有色金属研究总院深冷处理对CeO2添加超细WC-9Ni-Cr3C2硬质合金结构、性能与残余应力的影响硬质合金时凯华，刘小胡，昝秀颀，闵召宇，廖军硬质合金编辑部自贡硬质合金有限责任公司An Analytical Solution for Acoustic Emission Source Location for Known P Wave Velocity System MATHEMATICALPROBLEMS INENGINEERINGDong LJ (Dong, 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Guo(郭占成)中国科学院过程工程研究所中国科学院过程工程研究所二等奖（75篇）论文标题期刊名称作者推荐单位作者单位The application of zinc calcine as a neutralizing agent for the goethite process in zinc hydrometallurgy Hydrometallurgy 韩海生，孙伟，胡岳华，唐鸿鹄中南大学资源加工与生物学院中南大学资生院工业水表选型与经济效益运行分析计量技术李新峰河南中孚实业股份有限公司河南中孚实业股份有限公司Comparative studies on the initial stages of arc-sprayed and zinc-rich powder coatings in sulfur-rich environment Journal of Alloys andCompounds李红英，段俊颖，闽小兵中南大学材料科学与工程学院中南大学Electrochemical behavior of rolled Pb-0.8%Ag anodesin an acidic zinc sulfate electrolyte solution containingCl−ions Hydrometallurgy杨海涛，郭忠诚，陈步明，刘焕荣，张永春，黄惠，李学龙，付仁春，徐瑞东中国科学院过程工程研究所中国科学院过程工程研究所基于信号子空间增强和端点检测的大地电磁噪声压制物理学报李晋，汤井田，王玲，肖晓，张林成湖南师范大学物理与信息科学学院湖南师范大学物理与信息科学学院考虑侧向约束的预应力混凝土超静定结构次内力计算及影响江西理工大学学报邓通发，刘平平，肖佳明，王超众江西理工大学学报编辑部江西理工大学磁化处理对W6Mo5Cr4V2高速钢刀具加工质量的影响有色金属科学与工程刘政，郭颂，谌庆春有色金属科学与工程编辑部江西理工大学机电工程学院CuO-CO2-NH3-H2O体系孔雀石浸出的热力学分析有色金属科学与工程曹才放，王旭，赵天瑜，杨亮，熊辉辉有色金属科学与工程编辑部江西理工大学离子型稀土矿浸取工艺对资源、环境影响有色金属科学与工程邹国良，吴一丁，蔡嗣经有色金属科学与工程编辑部江西理工大学铜闪速炉反应塔内壁挂渣热力学模型探析有色金属科学与工程汪金良，张文海，童长仁有色金属科学与工程编辑部江西理工大学密度泛函理论及其在选矿中的应用有色金属科学与工程何桂春，蒋巍，项华妹，齐美超，康倩有色金属科学与工程编辑部江西理工大学试验研究渗流过程离子型稀土渗透性的变化规律有色金属科学与工程罗嗣海，黄群群，王观石，胡世丽，洪本根有色金属科学与工程编辑部江西理工大学Equilibrium between NO3- and NO2- in KNO3–NaNO2 melts: a Raman spectra study Chinese Optics Letters胡宪伟，喻宗鑫，高炳亮，石忠宁，于江玉，王兆文东北大学东北大学Influences of tensile pre-strain and bendingpre-deflection on bendingand tensile behaviors of an extruded AZ31Bmagnesium alloy Materials and DesignZhichao Ma(马志超）, Hongwei Zhao（赵宏伟), Xiaoli Hu（胡晓利）,Hongbing Cheng（程虹丙）, Shuai Lu（鲁帅）, Lin Zhang（张霖）吉林大学机械科学与工程学院吉林大学机械科学与工程学院Dynamic recrystallization behavior of a typical nickel-based superalloy during hot deformation Materials and DesignXiao-Min Chen(陈小敏)，Y.C.Lin(蔺永诚)，Dong-Xu Wen(温东旭)，Jin-Long Zhang(张金龙)，Min He(何敏)中南大学机电工程学院中南大学机电工程学院基于田口法的铜阳极泥微波浸出工艺中国有色金属学报(中文版) 马致远，杨洪英，陈国宝，吕阳，佟琳琳东北大学材料与冶金学院东北大学材料与冶金学院活性炭对钴矿物生物浸出的催化作用中国有色金属学报刘伟，杨洪英、佟琳琳、刘媛媛东北大学材料与冶金学院东北大学材料与冶金学院Beneficiation of cassiterite fines from a tin tailingslime by froth flotation Separation Science andTechnologyZhou Yongcheng(周永诚)，TongXiong(童雄)，Song Shaoxian(宋少先)，Xiao Wang(王晓)，ZhengbinDeng(邓政斌)，Xian Xie(谢贤)昆明理工大学昆明理工大学Effects of manganese nitrate concentration on the performance of an aluminum substrateβ-PbO2-MnO2-WC-ZrO2 composite electrode material International Journal ofHydrogen Energy杨海涛，陈步明，刘焕荣，郭忠诚，张永春，李学龙，徐瑞东昆明理工大学昆明理工大学云南格咱岛弧地苏嘎成矿岩体I型花岗岩年代学、地球化学研究及地质意义地质论评刘学龙，李文昌，张娜，尹光侯，邓明国昆明理工大学云南省地质调查局DFT study of ethyl xanthate interaction with sphalerite (1 1 0) surface in the absence and presence of copper Applied Surface Science刘建，文书明，邓久帅，陈秀敏，封奇成昆明理工大学昆明理工大学钼酸铵溶液的净化研究中南大学学报自然科学版俞娟，杨洪英，方钊，王斌，李林波，朱军西安建筑科技大学冶金工程学院西安建筑科技大学冶金学院深孔爆破成井在谦比希铜矿中的应用现代矿业施发伍中国有色矿业集团有限公司中色非洲矿业有限公司缓倾斜薄矿脉底板破碎矿体采矿方法研究有色金属（矿山部分）李占炎中国有色矿业集团有限公司中色卢安夏铜业有限公司广西大厂铜坑锌多金属矿体勘探方法探讨西部探矿工程魏宏炼，罗光克广西华锡集团股份有限公司铜坑矿广西华锡集团股份有限公司铜坑矿广西铜坑矿区重金属污染的防治实践中国矿山工程许远清，韦方景，张绍国，韦建宏广西华锡集团股份有限公司铜坑矿广西华锡集团股份有限公司铜坑矿两种新型水溶性庚铂衍生物的合成和抗癌活性研究无机化学学报姜婧，楼丽广，谌喜珠，徐永平，叶青松，刘伟平昆明贵金属研究所昆明贵金属研究所柠檬酸铅在柠檬酸钠溶液中溶解行为北京科技大学学报何东升，李巧双，杨典奇，杨聪，王贤晨，杨家宽武汉工程大学资源与土木工程学院武汉工程大学金属矿山可控循环风利用与节能金属矿山刘晓培，宫锐，常德强，曲元龙，柳静献沈阳有色冶金设计研究院沈阳有色冶金设计研究院Influence of Zr alloying on the mechanical properties,thermal stability and oxidation resistance of Cr-Al-Ncoatings Applied Surface ScienceW.Z.Li(李伟洲)，Q.Z.Chen(陈泉志)，T.Polcar，R.Serra，A.Cavaleiro广西大学材料科学与工程学院广西大学材料学院冲击荷载作用下花岗岩动力特性试验分析工程爆破郭连军，杨跃辉，华悦含，李林中国工程爆破协会工程爆破编辑部辽宁科技大学基于车载式火箭爆破带破冰破凌性能试验研究工程爆破杨旭升，梁秋祥，董德坤，张金辉，张连伟中国工程爆破协会工程爆破编辑部沈阳军区司令部工程科研设计院240m高钢筋混凝土烟囱爆破拆除及振动控制技术工程爆破张英才，范晓晓，盖四海，董保立，徐鹏飞，王晓中国工程爆破协会工程爆破编辑部河南理工大学土木工程学院黄金矿山大型球磨机综合节能研究及应用黄金谢敏雄，梅治福黄金杂志社山东黄金矿业（莱州）有限公司三山岛金矿H2SO4-NH4F-SbF3粗锑电解精炼体系研究黄金崔焱，林艳，谢刚，杨大锦黄金杂志社昆明冶金研究院The combined effects of ultrasonic wave and electric field on the microstructure and properties ofSn2.5Ag0.7Cu0.1RE/Cu soldered joints Journal of Materials Science:Materials in Electronics张柯柯，张晓娇，邱然锋，石红信，刘宇杰河南科技大学河南科技大学矿山大型机械设备智能集中润滑系统设计中国矿业李建，李建中，杨文龙，赵志刚赣州有色冶金研究所赣州有色冶金研究所Thermal transformation of pyrophyllite and alkali dissolution behavior of silicon Applied Clay ScienceGuanghui Li(李光辉)，JinghuaZeng(曾精华)，Jun Luo(罗骏)，Mingxia Liu(刘明霞)，Tao Jiang(姜涛)，Guanzhou Qiu(邱冠周)中南大学中南大学资源加工与生物工程学院Synchronous Volatilization of Sn, Zn, and As, andPreparation of Direct Reduction Iron (DRI) from a Complex Iron Concentrate via CO Reduction JOM李光辉，姜涛，游志雄，张元波，饶明军，文佩丹，郭宇峰中南大学中南大学资源加工与生物工程学院A new double reduction method for slope stabilityanalysis J. 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South Univ. 白冰，袁维，李小春中国科学院武汉岩土力学研究所中国科学院武汉岩土力学研究所考虑重金属污染岩石侵入面损伤的本构模型岩土工程学报程峰，王星华，莫时雄中国有色桂林矿产地质研究院有限公司中国有色桂林矿产地质研究院有限公司江西某白钨矿选矿工艺研究金属矿山郭玉武，魏党生，叶从新，韦华祖湖南有色金属研究院湖南有色金属研究院提高矽卡岩型多金属硫化矿床伴生贵金属回收的研究有色金属（选矿部分）陈代雄，肖骏，杨建文湖南有色金属研究院湖南有色金属研究院从锌电积阳极泥中回收锌和锰的试验研究湿法冶金蒋光辉，牛莎莎，陈海清，刘俊湖南有色金属研究院湖南有色金属研究院Separation of silica from pyrite cinder via reverse cationic flotation Journal of Chemical andPharmaceutical Research王全亮，冯其明湖南有色金属研究院湖南有色金属研究院湖北黄土咀铁矿地下水防治现代矿业李国山长沙有色冶金设计研究院有限公司长沙有色冶金设计研究院有限公司钛合金Ti6A14V高速磨削试验研究中国机械工程田霖，傅玉灿，杨路，赵家延中国机械工程杂志社南京航空航天大学地球化学对钨钼矿分离的借鉴中国有色金属学报赵中伟，何利华中南大学冶金与环境学院中南大学冶金与环境学院粗硫酸镍提取工艺及生产实践铜业工程苏峰，李敬忠，李俊标，周忠金隆铜业有限公司金隆铜业有限公司多晶硅副产物二氯二氢硅的应用研究有色冶金节能石何武，杨永亮，汤传斌，肖荣晖，严大洲中国恩菲工程技术有限公司中国恩菲工程技术有限公司高压酸浸技术开发及工程化利用世界有色金属刘诚，傅建国中国恩菲工程技术有限公司中国恩菲工程技术有限公司某矿开发中时间效应分析中国矿山工程王志远，朱瑞军中国恩菲工程技术有限公司中国恩菲工程技术有限公司尾矿库的雨虹特性及洪水计算方法选择中国矿山工程郑学鑫中国恩菲工程技术有限公司中国恩菲工程技术有限公司有色冶炼烟气骤冷收砷技术研究与应用中国有色冶金姚亮，李旭朋中国恩菲工程技术有限公司中国恩菲工程技术有限公司氨基修饰介孔分子筛SBA-15吸附水中Cu2+性能研究环境工程韦真周，魏建文，罗永红，慕江容，王姜婷，陆叶娟，宋建雄广西冶金研究院有限公司桂林理工大学三软大倾角煤层综采放顶煤技术与装备2014,第二届煤炭科技创新高峰论坛李鸿雷，刘海旺，陈宾河南豫联煤业集团有限公司河南豫联煤业集团有限公司新疆希勒库都克铜钼矿床黄铁矿微量元素和稀土元素特征矿产勘查龙灵利，王京彬，王玉往，王莉娟，廖震，赵路通，孙志远，李德东，高一菡北京矿产地质研究院北京矿产地质研究院Synthesis and electrochemical performance of cathodematerial Li1.2Co0.13Ni0.13Mn0.54O2 from spentlithium-ion batteries Journal of Power SourcesLi Li，Xiaoxiao Zhang，Renjie Chen，Taolin Zhao，Jun Lu，Feng Wu，KhalilAmine北京理工大学材料学院北京理工大学材料学院Crystal structure and hard magnetic properties of TbCu7-type Sm0.98Fe9.02–x Ga x nitrides Journal of Rare Earths权宁涛，张世荣，于敦波，李扩社，罗阳，靳金玲，张坤，刘宇超，李红卫北京有色金属研究总院北京有色金属研究总院，有研稀土新材料股份有限公司Raman spectra of RE2O3 (RE=Eu, Gd, Dy, Ho, Er,Tm, Yb, Lu, Sc and Y): laser-excited luminescence and trace impurity analysis Journal of Rare Earths余金秋，崔磊，何华强，颜世宏，胡运生，吴浩北京有色金属研究总院北京有色金属研究总院Effect of Si-N substituting for Al-O bonds on luminescence properties of Sr3AlO4F:Ce3+ phosphor Journal of Rare Earths马小乐，庄卫东，郭汉杰，刘荣辉，刘元红，胡运生，温晓帆北京有色金属研究总院北京有色金属研究总院Energy transfer from Eu2+ to Mn2+ in M5(PO4)3Cl (M= Ca, Sr) Journal of Luminescence杨凤丽，安炜，庄卫东，田光善，荆西平北京有色金属研究总院北京有色金属研究总院固相烧结阶段保温参数对Ti(C,N)基金属陶瓷显微组织和力学性能的影响硬质合金马遗萍，郑勇，周伟，赵毅杰，沈裕峰硬质合金编辑部南京航空航天大学硬质合金涂层刀片的金相检测硬质合金胡希川，刘风光，李克林硬质合金编辑部成都邦普合金材料有限公司有限元仿真预测高温合金切槽刀具寿命的初步探讨硬质合金刘志林，严宏志硬质合金编辑部中南大学高硫极细全尾砂充填料配比及输送特性试验研究中国矿山工程王怀勇，张爱民，贺茂坤中国矿山工程编辑部中国恩菲工程技术有限公司Near-net-shape tungsten-rhenium alloy parts produced by plasma spray forming and hot isostatic pressing Materials Transactions王跃明，熊翔，赵中伟，解路，颜建辉，闵小兵，郑峰中南大学冶金与环境学院湖南科技大学机电工程学院Facile synthesis of aluminum-doped LiNi0.5Mn1.5O4 hollow microspheres and their electrochemicalperformance for high-voltage Li-ion batteries Journal of Alloys andCompounds刘小林，李丹，莫乔铃，郭晓宇，杨潇潇，陈国新，钟盛文江西理工大学江西理工大学铽掺杂氟化钙绿色荧光粉的合成及发光性能光学学报廖金生，柳少华，王甘震，聂丽灵江西理工大学江西理工大学一个中心对称的（6,3）拓扑二维蜂窝网的Ni-咪唑基三脚架配合物的合成、结构及其介电性有色金属科学与工程于银梅，谭育慧，黄海平，熊剑波，王艳，高继兴，徐庆，唐云志江西理工大学江西理工大学油酸钠作用下金红石的浮选行为及作用机理中国有色金属学报王军，程宏伟，赵红波，覃文庆，邱冠周中南大学资源加工与生物工程学院中南大学Research on the Penetration Depth in AluminumReduction Cell with New Type of Anode and CathodeStructures JOMLiu Yan，Li yudong，Zhang Ting'an，Feng Naixiang东北大学材料与冶金学院东北大学砷的高效硫化回收技术在污酸处理中应用实践硫酸工业董冕，刘祖鹏，曹龙文大冶有色金属集团控股有限公司科学技术协会大冶有色金属有限责任公司冶炼厂Preparation and properties of plasma electrolyticoxidation coating on sandblasted pure titanium by acombination treatment Mater.Sci.Eng.C 王宏元山东大学材料科学与工程学院山东大学Silver nanowires with rounded ends: ammoniumcarbonate-mediated polyol synthesis, shape evolutionand growth mechanismCrystEngComm 刘绍宏，孙薄明，李继光，陈家林东北大学材料与冶金学院东北大学优秀奖（92篇）论文标题期刊名称作者推荐单位作者单位高纯度异丙基乙基硫氨酯的合成有色矿冶王咏梅，牟松，张海龙，郭靖宇中国有色集团沈阳矿业投资有限公司沈阳有研矿物化工有限公司。

Slater绝缘体磁性和电子结构的第一性原理研究

Advances in Condensed Matter Physics 凝聚态物理学进展, 2019, 8(1), 8-15Published Online February 2019 in Hans. /journal/cmphttps:///10.12677/cmp.2019.81002First-Principles Study on Magnetism andElectronic Structures of Slater InsulatorsZhigang Zhao1*, Wenjun Li2*, Bin Li2#, Lei Ti3, Zilong Miao3, Zhixiang Shi41College of Engineering, Nanjing Agricultural University, Nanjing Jiangsu2School of Science, Nanjing University of Posts and Telecommunications, Nanjing Jiangsu3College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing Jiangsu 4Department of Physics, Southeast University, Nanjing JiangsuReceived: Feb. 4th, 2019; accepted: Feb. 18th, 2019; published: Feb. 25th, 2019AbstractThe Slater transition is one of the metal-insulator transitions that occur due to the formation of an antiferromagnetic order. In this dissertation, we use ab initio package to study the electronic structures of two Slater insulator materials, NaOsO3and Cd2Os2O7, including electron energy bands and density of states by using the first-principle density functional calculation method.Furthermore, the effects of antiferromagnetic order, spin-orbit coupling (SOC) and electron cor-relation on the electronic structures and transition properties were investigated. We find that the electronic structures of NaOsO3 in the non-magnetic phase are continuous and showing the beha-vior of metal; while the G-type antiferromagnetic structure changes the electronic structures of NaOsO3, resulting in Slater transition. We find that the electronic structures of Cd2Os2O7in the non-magnetic phase are continuous and showing the behavior of metal. The conditions for the oc-currence of Slater transition in frustrated Cd2Os2O7are very severe. Only the noncollinear all-in-all-out antiferromagnetic structure with the spin-order interactions and 1.8 eV electron correlation can cause the Slater transition. It shows that the noncollinear all-in-all-out antiferro-magnetic structure is the magnetic ground state of Slater transition, and the spin-orbit coupling and the 1.8 eV electron correlation play a key role in eliminating the magnetic frustration.KeywordsBand-Structure, Antiferromagnetic Order, First-Principles CalculationSlater绝缘体磁性和电子结构的第一性原理研究赵志刚1*，李文君2*，李斌2#，提磊3，缪子隆3，施智祥4*共同第一作者。