CCTO特征晶体结构畸变的第一性原理

First-principles study of CCTO lattice distortion

为研究特征晶体结构和优异介电性能之间的内在联系,通过改变O的内坐标调整TiO_(6)八面体和CuO_(4)正方形的畸变,运用Materials Studio软件的CASTEP模块计算,对比了晶格畸变前后CaCu_(3)Ti_(4)O_(12)(简称CCTO)能带结构、原子态密度、成键状况及光频介电函数等性能参数变化,分析TiO_(6)八面体及CuO_(4)正方形的改变对CCTO介电性能所造成的影响,进一步确认本征结构与巨介电性能之间的内在联系。结果显示,TiO_(6)八面体畸变对光频介电常数影响不大,但CuO_(4)正方形对CCTO光频介电常数有着明显的制约作用。从内禀机制角度解释了CCTO的介电机理,为调控CCTO材料介电性能提供了新的思路。

In order to study the intrinsic relationship between characteristic crystal structure and excellent dielectric properties,the distortion of TiO_(6) octahedron and CuO_(4) square is adjusted by changing the internal coordinates of O,and calculated by using the CASTEP module of Materials Studio software.The changes of band structure,atomic density,bonding state and optical frequency dielectric function of CaCu_(3)Ti_(4)O_(12)(CCTO) before and after lattice distortion were compared,and their effects on the dielectric properties of CCTO were analyzed,and the intrinsic relationship between the intrinsic structure and the giant dielectric properties was further confirmed.In this paper,it is found that CuO_(4) squares have obvious restrictive effects on the CCTO optical frequency dielectric constant,but TiO_(6) octahedral distortion has little effect on the optical frequency dielectric constant.In this paper,the dielectric mechanism of CCTO is explained from the intrinsic mechanism,which provides a new idea for regulating the dielectric properties of CCTO materials.