Theoretical Study on Electronic Band Structureand Physical Properties if Ternary Compounds

三元化合物电子能带结构及物理性质的理论研究

基本信息

批准号：
04640339
负责人：
SUZUKI Naoshi
金额：
$ 1.34万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Electronic vand strucurures and total energies are calculated for intercalated compounds A_xTiS_2 (A = transition-metals, silver, and alkaline metals) and trnary intermetallic compounds Mn_2Sb, Mn_3GaC, and Fe_7Se_8 by using the LAPW method.1. A_xTiS_2 (A = transition-metals, silver, and alkaline metals) For the silver-intercalated compound Ag_x TiS_2 the selectronic states of silver atoms hybridize strongly with those of the host material, but a cohesive energy gain due to the hybrideization is rather small. On the other hand, the alkaline metal atoms only donate electrons to the host material. The chemical bonds between guest atoms and the host material are relatively weak for Ag_xTiS_2 and the alkline-metal-intercalated compounds compared with the transition-metal-intercalated compounds. From the total energy calculation it is confirmed that the ABC-stacking structure is more stable than the AB-stacking is favorable for Ag_xTiS_2.2. Ternary intermetallic compounds Mn_2Sb, Mn_3GaC, and Fe_7Se_8 (1) Mn_2Sb : From the total energies calculated as a function of the lattice constants, a and c, it is found that the ferrimagnetic state is more stable than the antiferromagnetic state. The evaluated value of the linear compressibility along the a-axis is larger than that along the c-axis. (2) Mn_3GaC : It is found that both the magnitude of the magnetic moment at each maganese site and its volume dependence are larger for the antiferromagnetic state than those for the ferromagnetic state. Further, the antiferromagnetic phase becomes more stable than the ferromagneric state in larger volume side. (39 Fe_7Se_8 : In the ferrimagnetic state, the magnetic moments at crystallographically inequivalent iron sites have almost the same values with each other. The photoemission and the optical conductivity spectra clculated from the electronic density of states are in good correspondence with the observations.

计算用于插入的化合物A_XTIS_2（A =过渡金属，银和碱金属）和TRNARY金属间化合物MN_2SB，MN_3GAC，MN_3GAC和Fe_7Se_8的插入式化合物A_XTIS_2（a =过渡金属，银和碱金属）计算电子材料诱导和总能量。 A_XTIS_2（a =过渡金属，银和碱金属）用于银嵌入式化合物AG_X TIS_2银原子的选择性态与宿主材料的选择性强烈融合，但是由于杂交化而引起的粘性能量增益很小。另一方面，碱性金属原子仅向宿主材料捐赠电子。对于AG_XTIS_2，与过渡金属间定位化合物相比，AG_XTIS_2和ALKLINE-METAL中学化合物之间的化学键相对较弱。从总能量计算中可以证实，ABC堆栈结构比AB堆积更稳定，对AG_XTIS_2.2有利。三元金属间化合物MN_2SB，MN_3GAC和Fe_7Se_8（1）Mn_2SB：根据晶格常数A和C计算出的总能量，发现铁磁性状态比抗Fiferromagnetic状态更稳定。沿A轴的线性可压缩性的评估值大于沿C轴的值。（2）MN_3GAC：发现每个Maganese位点的磁矩幅度及其体积依赖性对于抗磁磁状态的幅度都比铁磁性状态的磁矩均大。此外，在较大体积的一侧，抗铁磁相比铁磁态更稳定。（39 FE_7SE_8：在铁磁状态下，晶体上不相等的铁位点的磁矩彼此几乎具有相同的值。光发射和从状态的电子密度构成的光电导率光谱与观测值良好。