MgAl_2O_4绝缘性的第一性原理研究

First-principle Study on the Insulation of MgAl_2O_4

基于密度泛函理论的第一性原理研究了存在本征空位和间隙缺陷的MgAl_2O_4体系。缺陷形成能的结果表明,O_(i4)和V_O分别在富氧(O-rich)和缺氧(O-poor)条件下的形成能最低,两者均在体系中引入深能级,无法增强MgAl_2O_4的导电性。电子结构的结果表明,O_(i4)在价带顶和导带底均引入能级,V_O在禁带中引入深能级,分别存在这两种本征缺陷的MgAl_2O_4依然保持良好的绝缘性。

The native vacancy and interstitial defects in MgAl2O4 were studied with the first- principle methods based on density-functional theory. The results demonstrated that the defect formation of oxygen tetrahedral interstitial （O4） and oxygen vacancy （Vo） are the lowest under the O-rich and O-poor condition. Both Oi4 and Vo introduced deep energy levels in band gap, which can not enhance electrical conductivity of MgAl2O4. The results of electronic structure in- dicated that Oi4 introduced energy levels in the valence-band maximum and conduction-band mini- mum and Vo introduced deep energy levels in band gap. MgAl2O4 with Oi4 and Vo is still a good insulation.