Energy Release Effect In Antiferroelectrics

The energy release effect is an effect that happens during the process of withdrawing the electric field after charging electric energy into the materials, which can be represented by the amount of recoverable energy storage density. On the basis of the previously derived relationship between the antiferroelectric hysteresis loop with temperature from the phenomenological theory by considering two different responses of the two polarizations in opposite directions to an applied electric field, the relationship between the recoverable energy storage density with temperature during the process of withdrawing the electric field is systemically studied in the second-order phase transition antiferroelectrics. The results show that there are two peaks of the recoverable energy storage density in the temperature spectrum: the smaller energy density peak is in the antiferroelectric phase, and the other larger peak is in the paraelectric phase at the temperature slightly higher than the Curie temperature. When the temperature decreases from the Curie temperature, the recoverable energy storage density will gradually increase to the smaller peak and then slowly decrease. This conclusion is consistent with many experimental results on antiferroelectric materials including ceramics, thin films, and single crystals. The further analysis of the effect of the Gibbs free energy on the energy release effect shows that the two coefficients of the Gibbs free energy are essential for the width and height of the peak of recoverable energy storage density. Specifically, the smaller is the coefficient of the quadratic power of polarization, the wider is the temperature width of the peak, or temperature stability, the smaller is the coefficient of the fourth power of polarization, and the higher is the height of the released energy peak. These two parameters dominate the behaviors of polarization, energy storage characteristic, and the dielectric constant of the antiferroelectrics, and establish the correlation between the dielectric constant peak and the higher energy storage density peak. Therefore, the basic energy release effect can be determined from the dielectric properties.