The new developedγ/γʹCo–Al–Nb-base alloys show great potentials as high-temperature materials.However,finding appropriate compositions to improve performance of alloys still poses a great challenge to the developm...The new developedγ/γʹCo–Al–Nb-base alloys show great potentials as high-temperature materials.However,finding appropriate compositions to improve performance of alloys still poses a great challenge to the development of Co–Al–Nb-base alloys.Motivated by the lack of alloying effects on fundamental properties of criticalγʹphase,we systematically performed a theoretical investigation on the effect of alloying elements TM(TM:Ti,V,Cr,Zr,Mo,Ta,W,Re,and Ru)on phase stabilities and mechanical properties of L1_(2)-typeγʹ(Co,Ni)_(3)(Al,Nb).By analyzing the stability ofγʹphase with respect to its competitive B2 and D0_(19) phases,the results shown that Ti,V,and Cr enhance the L1_(2) stability and widen the L1_(2)–D0_(19) energy barrier,in which V yields the maximum influence.The analysis of electronic structure indicated that the alternation of valence electrons at fermi level would be the atomic origin for doping TM inγʹphase.The calculated results of mechanical properties shown that V and Cr are expected to be optimal dopant for enhancing the strength and the ductility ofγʹphase.The addition of Ta is also beneficial for enhancing the strength at the slight expense of ductility ofγʹphase.By drawing the mechanical maps,the preferred composition range for the phases with desired properties is roughly demarcated in theory for the multi-addition of V/Cr and V/Ta inγʹphase.The findings would be useful for optimizing the performance of novelγ/γʹCo–Al–Nb-base superalloys.展开更多
A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Bu...A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Burke-Ernzerhof form in the framework of density functional theory.The supercell structure shows a trend from expanding to shrinking with the increasing Sb concentration.The increasing Sb concentration induces the band gap narrowing.Optical transition has shifted to the low energy range with increasing Sb concentration.Other important optical constants such as the dielectric function,reflectivity,refractive index,and electron energy loss function for Sb-doped SnO2 are discussed.The optical absorption edge of SnO2 doped with Sb also shows a redshift.展开更多
The existence of intrinsic ferromagnetic semiconductors(FMSs)in twodimensional(2D)materials has been a long-term concern and pursuit.Recent breakthroughs in the 2D FMSs,such as CrGeTe3 and CrX3(X=Cl,Br,I)from bulk dow...The existence of intrinsic ferromagnetic semiconductors(FMSs)in twodimensional(2D)materials has been a long-term concern and pursuit.Recent breakthroughs in the 2D FMSs,such as CrGeTe3 and CrX3(X=Cl,Br,I)from bulk down to monolayer,have stimulated intensive researches on new physical phenomena and creative concepts.This minireview mainly summarizes recent progress of 2D intrinsic FMSs in theoretical side,and focuses on the ongoing strategies proposed to enhance ferromagnetism,involving the mechanisms of magnetic exchange interaction and the significance of magnetic anisotropy.Meanwhile,spin-related multifunctionality with ultrathin FMSs and their van de Waals heterostructures in magnetoelectric,valleytronic,and nondissipative electronic technology are introduced,as well as the current challenges and the prospects in this field are discussed.展开更多
本文使用在位库仑作用、局域密度近似下的投影缀加平面波方法,计算了钙钛矿材料锆酸锶（SrZrO3）正交相掺Co前后的晶体结构、电子能带结构及掺Co后的磁性质.结果表明：当Co Co之间的间距L为0.4097 nm,即最近邻,且体系为铁磁构型时对应...本文使用在位库仑作用、局域密度近似下的投影缀加平面波方法,计算了钙钛矿材料锆酸锶（SrZrO3）正交相掺Co前后的晶体结构、电子能带结构及掺Co后的磁性质.结果表明：当Co Co之间的间距L为0.4097 nm,即最近邻,且体系为铁磁构型时对应的总能最低,表明 Co 掺杂进入钙钛矿 B位后,容易出现 Co 离子的团簇聚集,出现铁磁性；电子能带结构图显示Co部分替代Zr4＋后变为 Co4＋（3d5）,相对于标准化合价的 Co3＋（3d6）,有一条空的d轨道未占据,又由于掺杂Co后其d轨道与近邻O 的p轨道有强烈杂化,有部分Co的d轨道及O 的部分p轨道越过价带进入带隙,在0~2.60 eV之间,自旋向上出现3条Co 3d能带,自旋向下出现7条 Co 3d能带,且导带底向低能移动；部分Co离子替代钙钛矿B位的Zr4＋后,体系出现磁性,由于 Co 离子形式化合价为＋3,替代 Zr4＋后,这种空穴掺杂将在价带顶引入空的掺杂能级；态密度结果表明该能级为 Co4＋离子部分空的d轨道,通过 O 的p轨道,造成体系中Co3＋、Co4＋离子的出现,而它们之间的双交换耦合使得体系出现铁磁性.展开更多
Lithium ion batteries（LIBs） are currently best energy storage devices providing rechargeable electrical storage to wide variety of applications – from portable electronics to automobiles. Though, these batteries ar...Lithium ion batteries（LIBs） are currently best energy storage devices providing rechargeable electrical storage to wide variety of applications – from portable electronics to automobiles. Though, these batteries are fully adopted, widely used and commercialized, but researchers are still extensively working on their constituent materials and developing technology to improve their performance. A major part of related research activities is devoted to the electrode of the battery for improvement in its performance thereby addressing issues like safety, lifetime, specific capacity, energy density and most importantly abundance and cost. There are number of cathode materials that have been proposed and tested at laboratory scale and subsequently utilized in commercialized batteries ever since the appearance of LIBs. Owing to the availability of improved computational resources in the last decade, first principles calculation has become a reliable tool and played a vital role to predict the material properties of electrodes prior to their experimental analysis. This review gives a comprehensive insight and thorough analysis of the global research efforts related to the cathode materials based on first principles framework, sheds light on current status of knowledge and explores the ways forward.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52371014 and U22B20132)the Shenzhen Science and Technology Program(No.JCYJ20230807091401004)+1 种基金the Fundamental Research Funds for the Central Universities(No.20720230036)the Guided Subject of Dean’s Fund(No.YZJJ-YDL-0004).
文摘The new developedγ/γʹCo–Al–Nb-base alloys show great potentials as high-temperature materials.However,finding appropriate compositions to improve performance of alloys still poses a great challenge to the development of Co–Al–Nb-base alloys.Motivated by the lack of alloying effects on fundamental properties of criticalγʹphase,we systematically performed a theoretical investigation on the effect of alloying elements TM(TM:Ti,V,Cr,Zr,Mo,Ta,W,Re,and Ru)on phase stabilities and mechanical properties of L1_(2)-typeγʹ(Co,Ni)_(3)(Al,Nb).By analyzing the stability ofγʹphase with respect to its competitive B2 and D0_(19) phases,the results shown that Ti,V,and Cr enhance the L1_(2) stability and widen the L1_(2)–D0_(19) energy barrier,in which V yields the maximum influence.The analysis of electronic structure indicated that the alternation of valence electrons at fermi level would be the atomic origin for doping TM inγʹphase.The calculated results of mechanical properties shown that V and Cr are expected to be optimal dopant for enhancing the strength and the ductility ofγʹphase.The addition of Ta is also beneficial for enhancing the strength at the slight expense of ductility ofγʹphase.By drawing the mechanical maps,the preferred composition range for the phases with desired properties is roughly demarcated in theory for the multi-addition of V/Cr and V/Ta inγʹphase.The findings would be useful for optimizing the performance of novelγ/γʹCo–Al–Nb-base superalloys.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No. BUPT2009RC0412the National Natural Science Foundation of China under Grant Nos. 60908028 and 60971068
文摘A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1xO system.The simulations are based upon the method of generalized gradient approximations with the Perdew-Burke-Ernzerhof form in the framework of density functional theory.The supercell structure shows a trend from expanding to shrinking with the increasing Sb concentration.The increasing Sb concentration induces the band gap narrowing.Optical transition has shifted to the low energy range with increasing Sb concentration.Other important optical constants such as the dielectric function,reflectivity,refractive index,and electron energy loss function for Sb-doped SnO2 are discussed.The optical absorption edge of SnO2 doped with Sb also shows a redshift.
基金Jiangsu 333 Project,Grant/Award Number:BRA2016353Natural Science Foundation of China,Grant/Award Numbers:21525311,21773027+1 种基金National Key Research and Development Program of China,Grant/Award Number:2017YFA0204800Scientific Research Foundation of Graduate School of Southeast University,Grant/Award Number:YBPY1969。
文摘The existence of intrinsic ferromagnetic semiconductors(FMSs)in twodimensional(2D)materials has been a long-term concern and pursuit.Recent breakthroughs in the 2D FMSs,such as CrGeTe3 and CrX3(X=Cl,Br,I)from bulk down to monolayer,have stimulated intensive researches on new physical phenomena and creative concepts.This minireview mainly summarizes recent progress of 2D intrinsic FMSs in theoretical side,and focuses on the ongoing strategies proposed to enhance ferromagnetism,involving the mechanisms of magnetic exchange interaction and the significance of magnetic anisotropy.Meanwhile,spin-related multifunctionality with ultrathin FMSs and their van de Waals heterostructures in magnetoelectric,valleytronic,and nondissipative electronic technology are introduced,as well as the current challenges and the prospects in this field are discussed.
文摘本文使用在位库仑作用、局域密度近似下的投影缀加平面波方法,计算了钙钛矿材料锆酸锶（SrZrO3）正交相掺Co前后的晶体结构、电子能带结构及掺Co后的磁性质.结果表明：当Co Co之间的间距L为0.4097 nm,即最近邻,且体系为铁磁构型时对应的总能最低,表明 Co 掺杂进入钙钛矿 B位后,容易出现 Co 离子的团簇聚集,出现铁磁性；电子能带结构图显示Co部分替代Zr4＋后变为 Co4＋（3d5）,相对于标准化合价的 Co3＋（3d6）,有一条空的d轨道未占据,又由于掺杂Co后其d轨道与近邻O 的p轨道有强烈杂化,有部分Co的d轨道及O 的部分p轨道越过价带进入带隙,在0~2.60 eV之间,自旋向上出现3条Co 3d能带,自旋向下出现7条 Co 3d能带,且导带底向低能移动；部分Co离子替代钙钛矿B位的Zr4＋后,体系出现磁性,由于 Co 离子形式化合价为＋3,替代 Zr4＋后,这种空穴掺杂将在价带顶引入空的掺杂能级；态密度结果表明该能级为 Co4＋离子部分空的d轨道,通过 O 的p轨道,造成体系中Co3＋、Co4＋离子的出现,而它们之间的双交换耦合使得体系出现铁磁性.
基金Higprovide financial support vide 6509/Punjab/NRPU/R&D/HEC/2016
文摘Lithium ion batteries（LIBs） are currently best energy storage devices providing rechargeable electrical storage to wide variety of applications – from portable electronics to automobiles. Though, these batteries are fully adopted, widely used and commercialized, but researchers are still extensively working on their constituent materials and developing technology to improve their performance. A major part of related research activities is devoted to the electrode of the battery for improvement in its performance thereby addressing issues like safety, lifetime, specific capacity, energy density and most importantly abundance and cost. There are number of cathode materials that have been proposed and tested at laboratory scale and subsequently utilized in commercialized batteries ever since the appearance of LIBs. Owing to the availability of improved computational resources in the last decade, first principles calculation has become a reliable tool and played a vital role to predict the material properties of electrodes prior to their experimental analysis. This review gives a comprehensive insight and thorough analysis of the global research efforts related to the cathode materials based on first principles framework, sheds light on current status of knowledge and explores the ways forward.
