Mg掺杂对CaMnO_3基热电氧化物电子结构及电性能的影响研究

Effect of Mg Doping on Electronic Structure and Electrical Properties of CaMnO_3 Thermoelectric Oxide

采用超软赝势密度泛函理论计算的方法研究了Mg掺杂Ca位CaMnO_3基复合氧化物的能带结构、电子态密度和电荷分布状况,在此基础上分析了Mg掺杂氧化物的电性能。结果表明,Mg掺杂CaMnO_3氧化物仍然呈间接带隙型能带结构,带隙宽度由0.756 e V减小到0.734 e V。CaMnO_3氧化物和Mg掺杂CaMnO_3氧化物的自旋态密度曲线极值点均位于为-0.8 e V附近。Mg掺杂CaMnO_3氧化物中Mn原子对体系费米面态密度的贡献有所减小,O原子和Ca原子对体系费米面态密度的贡献有所增大。Mg原子比Ca原子具有更强的释放电子的能力,Mg掺杂对于CaMnO_3氧化物属于电子型掺杂。Mg掺杂CaMnO_3氧化物导电性能增强,电性能提高。

The electronic structure,density of states and charge populations of the Mg doped CaMnO3 oxide for Ca site has been studied by the psudo-potential density funtional theory calculation method,the electrical properties of the doped oxide have been analyzed thereafter. The calculational results show that the Mg doped CaMnO3 oxide has indirect band gap yet,the band gap has been slightly decreased from 0.756 e V to 0. 734 e V. The peak value of density of states curves locates at-0. 8 e V for the pure CaMnO3 oxide and the Mg doped CaMnO3 oxide. The Mn contributes less to density of states at Fermi level,however the O atom and the Ca atom contribute more to density of states at Fermi level. The Mg has stronger capability of releasing electrons into the system than that of the Ca,it should belong to electron carrier doping type for the Mg doping for Ca for the CaMnO3 oxide system. The Mg doping for Ca shouldenhance the electrical conduction capablity for the CaMnO3 oxide,the electrical property should be strengthed.