第一性原理计算分析冲击压缩下MgO电导率突降起因  

Analysis of the Causes for Abrupt Drop of Electronic Conductivity of MgO under High Pressure Using First Principle Calculation

作　　者：房勇[1] 杨改蓉[2] 何林[1] 纪红萱[1] 何旭[1] 

机构地区：[1]四川师范大学物理与电子工程学院,成都610066 [2]成都纺织高等专科学校基础部,成都611731

出　　处：《西南大学学报（自然科学版）》2009年第9期93-96,共4页Journal of Southwest University(Natural Science Edition)

基　　金：国家自然科学基金资助项目(10299040);四川师范大学重点资助项目

摘　　要：为了解释冲击实验在压力90 GPa附近观测到MgO电阻率突降的现象,采用第一性原理平面波超软赝势方法,结合广义梯度近似(GGA),首先计算了MgO理想晶体在105 GPa压力范围内的电子能带结构,得出理想晶体MgO能隙随压力的变化关系.结果表明压力增加引起能隙的降低,不能解释实验上观测到的现象.其次还计算了在90 GPa压力下氧空位对MgO能带结构的影响,结果表明空位点缺陷可能是引起MgO电阻率突降的一个物理机制.Shock experiment of MgO showed that there was an onset of its conductivity near 90 GPa. To analyze this phenomenon, based on the first-principle ultrasoft psuedopotential method, we investigated the pressure dependence of the band gap of perfect MgO crystal under 105 GPa. The results indicated that the increase of the band gap was not the reason why the conductivity onset occurred near 90 GPa. We also analyzed how the O vacancy affected the density of states under 90 GPa. The calculation showed that point defect might be one of the reasons for increase of conductivity.

关 键 词：氧化镁 高压 电阻率 点缺陷 

分 类 号：O482.4[理学—固体物理]