氧离子导体La_2Mo_(2-x)M_xO_9(M=Cr,W)的理论研究  

Theorectical study of the oxide-ion conductor La_2Mo_(2-x)M_xO_9(M=Cr,W)

作　　者：陈跃云[1] 侯春菊[1,2] 孔祥山[1] 刘长松[1] 王先平[1] 方前锋[1] 

机构地区：[1]中国科学院固体物理研究所,合肥230031 [2]江西理工大学理学院,赣州341000

出　　处：《物理学报》2011年第4期510-516,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10674135;50672100)资助的课题~~

摘　　要：采用第一性原理方法研究了高温β-La2Mo2O9中Mo被Cr或W取代后晶体的结构性质和高温相稳定性.研究发现Cr和W分别倾向于占据具有4配位数和5配位数的Mo位.W取代体系晶胞参数相对取代浓度非线性变化.该非线性变化与W离子取代位置配位数降低以及体系内La—O和Mo(W)—O平均键长非线性变化有关.内聚能计算表明W取代Mo后能够有效稳定高温相结构,降低相变温度.La4Mo3W1O18体系中氧离子扩散研究表明W取代体系中氧离子扩散激活能的增大主要是因为取代体系内形成了较强的W—O键.We perform the first-principles study of the structural properties and the high temperature phase stabilization of Cr,W-doped β-La2Mo2O9.We find that Cr prefers the site with four coordination numbers and W atom preferentially occupies the site with five coordination numbers.The nonlinear dependence of cell parameter on W content in W-doped systems results from the nonlinear change in Mo（W）-O and La-O bond lengths with W content and the decrease of coordination number around W occupied site.The decrease of cohesive energy with the W-doped concentration is conducive to the understanding of the stabilization of the β-La2Mo2-x WxO9 at lower temperature.The appearance of stronger W-O bond leads to the increase of the energy barrier of oxygen-ion concerted motion in W-dopedβ-La2Mo2O9.

关 键 词：氧离子导体 第一性原理 晶体结构 相稳定性 

分 类 号：O614.331[理学—无机化学]