基于第一性原理的BaTiO_3陶瓷临界尺寸的研究

First Principle Study on Critical Dimension of BaTiO_3 Ceramics

采用WIEN2K软件,基于第一性原理对具有不同晶格常数的BaTiO3晶胞结构的特性进行了模拟分析。计算了不同晶胞结构中的电荷密度分布,分析了体积与能量的关系对晶胞结构稳定性的影响。结合试验结果探讨了尺寸效应对瓷体铁电性的影响,找到了晶胞能量最低的状态以及电子轨道杂化最显著的晶胞尺寸。从而确定了晶胞铁电性存在的晶粒的临界尺寸为10～15 nm。

The properties of nanocrystalline BaTiO3 structure with different lattice constants were simulated and analyzed by WIEN2K based on the first principle. The density of electrons under different cell lattice was calculated and the stability of different structure was analyzed from the relationship of the change of lattice total energy with lattice volume. Based on the experimental data, the effect of grain size on theferroelectricity of lattice was discussed in order to find the cell parameters corresponding to the condition under which the unit cell keeps the state with the lowest energy and most significant electron orbital hybridization. As a result, the critical grain size for the existence of ferroelectricity in the unit cell was determined ranging from 10 nm to 15 nm.