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化学学报
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化学学报 ›› 2009, Vol. 0 ›› Issue (1): 19-26. 上一篇    下一篇

研究论文

PMN和PMNT中几种局域结构与晶格形变的从头算研究

徐红兰缪强2,罗豪甦   

  • 投稿日期:2008-05-16 修回日期:2008-08-08 发布日期:2009-12-30
  • 通讯作者: 缪强 E-mail:cheminfo@nju.edu.cn

Ab initio Study on Local Structure and Lattice Deformation in Selected PbMg1/3Nb2/3O3 and PbMg1/3Nb2/3O3-PbTiO3 (PMNT) Alloy

  • Received:2008-05-16 Revised:2008-08-08 Published:2009-12-30

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本文建立了钙钛矿结构铌镁酸铅PMN的2×2×3复晶胞模型；采用ab initio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0.74 a.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。

关键词: PMN；PMNT；ab initio；局域结构；晶格形变

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 energy difference between the lowest and the highest in PMN supercell models is about 0.74 a.u. (1940 kJ). Pb2+ lattice distortion may be the main factor in the PMN system’s deformation. Less MgO6 is favorable for Ti’s substitution of Nb. The configuration distribution and local deformation in lattice is dependent on the process of PMNT.

Key words: PMN; PMNT; Ab initio; Local structure; deformation