中文摘要：

通过原子环境计算分析正交相SrBi4Ti4O15（SBTi）的空间键络结构,根据固体与分子经验电子理论（EET）计算正交相SrBi4Ti4O15（SBTi）的价电子结构,进而求得晶体中各原子的有效价电子数。根据空间群理论构建SBTi铁电-顺电相变过程中的正交顺电结构（Aama）和四方顺电结构（I4/mmm）,并通过原子坐标分析得到相变过程中晶体内各原子的原子位移。最后根据自发极化与原子位移和原子有效价电子数之间的关系,求得正交相SBTi沿a轴方向的自发极化强度为25.81μC/cm2,与实验结果和其他理论参考值吻合较好。

英文摘要：

The chemical bonds structures were analyzed by the atomic environment calculation method, and the valence electron structure of orthorhombic phase SrBiaTi4O15 was calculated according to the EET theory, the numbers of the effective valence electrons of each atom in SrBi4Ti4O15 were obtained. Furthermore, according to the theory of crystal space group, the structures of orthogonal paraelectric phase （Aama） and the tetragonal paraelectric phase （14/mmm） in the ferroelectric-paraelectric phase transition were constructed, and the atomic displacements in the phase transition were calculated by the atomic coordinate analysis. The spontaneous polarization in SrBiaTi4O15 was studied based on the atomic displacements and atomic effective valence electrons numbers. The calculated spontaneous polarization strength in ferroelectric SrBiaTi4O15 along the a axis is 25.81 μC/cm2, which is in good agreement with the experimental and other theoretical results.