摘要
建立了钙钛矿结构铌镁酸铅PbMg1/3Nb2/3O3(PMN)的2×2×3复晶胞模型;采用abinitio方法讨论了PMN晶体各种可能构型的稳定性;选取了PMN三种高、中、低稳定性的代表构型,并对Ti替换B位离子后的结构进行了结构优化.计算结果表明复晶胞刚性模型的最低和最高能量差约0.74a.u.(1940kJ);Pb2+离子结构框架的形变是PMN晶格发生形变的主要因素;在不考虑被替换离子电荷差异的情况下,MgO6含量越少越有利于Ti离子替换Nb与晶胞的形变.PMNT材料中构型的分布和局域形变取决于生长PMNT材料的工艺过程.
Perovskite models of supercell (2 × 2 × 3) were set up for PbMg1/3Nb2/3O3 (PMN). Ab initio computations were performed for understanding the configuration distribution of PMN. The largest energy difference of the studied PMN supercell models was about 0.74 a.u. (1940 kJ). Pb^2+ lattice distortion may be the main factor for the PMN system deformation. Less MgO6 is favorable for Ti substitution of Nb. The configuration distribution and local deformation in lattice are dependent on the preparation process of PMNT.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2009年第1期19-26,共8页
Acta Chimica Sinica