铁电体的极化储能效应

Polarization energy storage effect of ferroelectrics

三维铁电体的偶极子等概率地分布在晶格取向相关的特定极化方向上.外加电场后,各个方向的偶极子对电场的响应不同,导致了各种场致效应.最基本的效应是电场对极化强度在相变温区的诱导和转向,导致铁电体在相应温区实现了高的储能密度效应.基于铁电体德文希尔理论三维吉布斯自由能与极化强度的关系,得到了二阶相变铁电体偶极子的诱导及取向对极化储能密度和放电能量密度的影响.研究结果显示:低电场下储能峰低于居里温度,并随电场增大接近并超过居里温度;两个铁电参量的比值对铁电体的极化行为、电滞回线和储能密度具有关键影响并使其相互关联.同时还发现介电峰的温度宽度对应电滞回线形状变化的温度宽度和储能密度峰的温度宽度,且储能密度峰越高,峰的温区越窄.

The dipole of a three-dimensional ferroelectric is distributed homogeneously in specific polarization directions related to its lattic orientations. Upon applied electric field, dipoles in all directions respond differently to electric field, resulting in various field-induced effects.The most basic effect is polarization induction effect by electric field sharply in the phase transition temperature region, which results in higher energy storage density in the corresponding temperature region. Based on the relationship between the threedimensional Gibbs free energy and polarization in ferroelectrics from the Devonshire theory, the influences of the induced effect and reorietation of the dipole of ferroelectric on the polarization energy storage density and discharge energy density are obtained. The results show that the peak temperature of energy storage density under low electric field is lower than the Curie’s temperature, and it approaches and exceeds the Curie’s temperature with the increase of electric field. The ratio of two ferroelectric parameters has significant influence on the polarization behavior, hysteresis loop and energy storage density of ferroelectrics and causes their correlations, in which the temperature width of the dielectric peak corresponds to the temperature width of the shape change of hysteresis loop and the temperature width of the energy storage density peak. The higher the energy storage density peak is, the narrower the temperature area of the peak is.