TiO6氧八面体缺陷对钛酸铜钙电子结构与光学性质影响的第一性原理研究

Effect of TiO6 Octahedron Structure Defects on the Electronic Structure and Optical Properties of CaCu3Ti4O12 by First-Principles

TiO6氧八面体结构是钛酸铜钙（CaCu3Ti4O12，CCTO）的基本骨架，直接关系着CCTO光学和电学性能的表现，其在各种频率下介电、光学性能的响应的研究有利于揭示其巨介电性能的根源。为了探索TiO6氧八面体骨架对CCTO各种频率下介电、光学性能的贡献，以及Ti、O元素的作用，构建了CCTO体块及具有氧空位、钛空位的CCTO模型，并采用基于密度泛函理论的第一性原理赝势平面波方法，对三种模型进行了几何结构、电子密度分布和光学性能的计算与分析。计算结果表明，氧空位和钛空位对几何结构和电子密度分布有着显著的影响，计算得到三种模型的介电函数，从而推出其他光学性质如折射率、反射率、吸收率和光电导率等，同时得出氧空位对CCTO光学性能的各向异性起着关键作用。

TiO6 octahedron structure is the basic framework of CaCu3Ti4O12 （CCTO）, which associates with performance of optical and electronic properties, the investigation of dielectric and optical properties under various frequency region contribute to reveal origin of high dielectric constant. In order to explore the contributions of TiO6 octahedron to optical and electronic properties under various frequency region and the impacts of titanium and oxygen element, the model of ideal CCTO bulk, CCTO with oxygen vacancy and titanium vacancy are established, the structure, electronic density distribution and optical properties of three models are calculated and analyzed by plane- wave pseudo-potential method of first-principle calculation based on density functional theory. The calculated results show that oxygen vacancy and titanium vacancy have significant influences on structure and electronic density distribution, moreover, the optical properties such conductivity are deduced from the calculated dielectric anisotropic of CCTO optical properties crucially. as refractive index, reflectivity, absorbance, and optical function of three models above, and oxygen vacancy affect