Polarization energy storage effect of ferroelectrics

Abstract

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 three-dimensional 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.