CAJ | 학술논문

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.
본문사용재위고륜작용、국역밀도근사하적투영철가평면파방법,계산료개태광재료고산송(SrZrO3)정교상참Co전후적정체결구、전자능대결구급참Co후적자성질.결과표명：당Co Co지간적간거L위0.4097 nm,즉최근린,차체계위철자구형시대응적총능최저,표명 Co 참잡진입개태광 B위후,용역출현 Co 리자적단족취집,출현철자성；전자능대결구도현시Co부분체대Zr4+후변위 Co4+(3d5),상대우표준화합개적 Co3+(3d6),유일조공적d궤도미점거,우유우참잡Co후기d궤도여근린O 적p궤도유강렬잡화,유부분Co적d궤도급O 적부분p궤도월과개대진입대극,재0~2.60 eV지간,자선향상출현3조Co 3d능대,자선향하출현7조 Co 3d능대,차도대저향저능이동；부분Co리자체대개태광B위적Zr4+후,체계출현자성,유우 Co 리자형식화합개위+3,체대 Zr4+후,저충공혈참잡장재개대정인입공적참잡능급；태밀도결과표명해능급위 Co4+리자부분공적d궤도,통과 O 적p궤도,조성체계중Co3+、Co4+리자적출현,이타문지간적쌍교환우합사득체계출현철자성.
The structural,electronic properties,and the ferromagnetism of Co-doped orthorhombic SrZrO3 are calculated using the first-principles methods,which are performed within the density functional theory(DFT)using the projector augmented wave(PAW)implemented in the Vienna ab initio Simulation Package(VASP),and the exchange-correlation potential is treated in the local density approximation using the Ceperly-Alder scheme.SrZrO3 has been the subject of investigations because of its technological applications.For instance,the wide band gap and high dielectric constant of SrZrO3 can be used in the electronic industry,and its refractory properties are of interest in hightemperature applications.The first-principles methods have been a powerful tool for obtaining accurate ground state and indicating the relevance between the microscopic structure and the properties.The lattice parameters and atomic positions are relaxed until the total energy changed by less than 10-5 eVper conventional cell and residual force is smaller than 0.01 eV/?.All the calculations reach good convergence.The calculated results show that the Zr atoms in B sites of perovskite structure substituted by Co atoms induce the ferromagnetism in the SrZr0.875 Co0.125 O3 .The results showed that,when the spacing between the Co Co is 0.4097 nm,i.e.nearest neighbor,and the system is the the ferromagnetic configuration,the calculating engery is corresponding to the minimum total energy, which indicate that the Co dope into the perovskite B bit to come into being the Co ion clusters and to appear ferro-magnetic.The electronic band structure diagram states clearly that the Co,replacing partly Zr4+,becomes the Co4+(3d5 ),which has an empty dorbital not being occupied relativing to the standardized aggregate price of Co3+(3d6 ).Because of doped Co dorbitals and Op orbitals have a strong hybrid to shift up the top of the valence band and shift down the bottom of the conduction band.It means that the doped of Co reduces the band gap.It also appears the three Co3d bands (up-spin)and the seven Co3d bands (down-spin)between 0 and 2.60 eV.The substitution induces the hole due to+3 valence of Co ions.The results of the proj ected local densities of states shows that the doped energy level are the partly empty d orbits of the Co4+ ions.The double exchange interaction between Co3+ and Co4+ ions is believed to be the origin of magnetism in the SrZr0.875 Co0.125 O3 .