【摘 要】
：
根据晶体空间群理论,对SrBi_2Ta_2O_9进行了从正交相到四方相的晶体重构,计算出SrBi_2Ta_2O_9在铁电相变中的原子位移,确定了SrBi_2Ta_2O_9沿a轴方向的自发极化。在此基础上,
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根据晶体空间群理论,对SrBi_2Ta_2O_9进行了从正交相到四方相的晶体重构,计算出SrBi_2Ta_2O_9在铁电相变中的原子位移,确定了SrBi_2Ta_2O_9沿a轴方向的自发极化。在此基础上,采用固体与分子经验电子理论(EET)计算了SrBi_2Ta_2O_9的价电子结构,进而得到SrBi_2Ta_2O_9中各原子的有效价电子数,由原子位移和有效价电子数求得正交铁电相SrBi_2Ta_2O_9的自发极化强度为18.14μC/cm~2,与实验数据和其他理论方法的结果吻合较好。
According to the crystal space group theory, the crystal structure of SrBi_2Ta_2O_9 from quadrature phase to tetragonal phase was reconstructed. The atomic displacement of SrBi_2Ta_2O_9 during the ferroelectric phase transition was calculated, and the spontaneous polarization of SrBi_2Ta_2O_9 along the a-axis was determined. On this basis, the valence electron structure of SrBi_2Ta_2O_9 was calculated by empirical electron theory (EET) of solid and molecule (EET), and the number of effective valence electrons of each atom in SrBi_2Ta_2O_9 was obtained. From the atomic displacement and effective valence electron number, The spontaneous polarization of SrBi_2Ta_2O_9 was 18.14μC / cm ~ 2, which was in good agreement with the experimental data and other theoretical methods.
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