铁电相变中极化与介电性的随机场效应

基于随机场Ising模型描述的有序无序相变中偶极子在电场作用下的反转运动, 研究了有序无序相变过程中电场与极化强度的关系. 认为tanh(x) 的函数关系与位移型二阶铁电相变极化强度随电场变化的实验结果完全相同. 由此得出基本结论: 偶极子的集体转向造成了极化强度的增大并等同于内电场的增加. 通过区分光学模和偶极子对介电隔离率的贡献, 考虑偶极子极化对介电常数复数形式的频率色散关系, 发现从高斯分布的居里温度可以导出二阶铁电相变过程中介电常数与温度和频率的色散关系. 关键词： 铁电相变 极化强度 随机场

Random field effect of polarization and dielectric permittivity in ferroelectric transitions

Based on reversion motion of dipoles in ferroelectrics under the electric field in the random field Ising model, the relationship between electric field and polarization in order-disorder transition is investigated, and the function tanh(x) for the electric field in order-disorder transition is coincident with the experimental relationship between electric field and polarization in the second order ferroelectric transition. Therefore, increases in polarization and internal poling field are due to the collective motion of dipoles, where electric field and temperature are critical in the polarization and Gibbs free energy. By distinguishing the contributions between optic mode and polarization portion with a gaussian-type distribution of Curie-temperature, and considering a complex dispersion form of dielectric permittivity contributed by dipoles, the relationships between dielectric permittivity and temperature, as well as frequency, are derived.
Keywords： ferroelectric transition polarization random field