Indirect Electrocaloric Evaluation: Influence of Polarization Hysteresis Measurement Frequency

This study investigates the influence of applied electric field frequency for polarization-electric field (P-E) loops on indirect electrocaloric evaluation. Soft lead zirconate titanate (PZT) ceramic is used as a model material. The P-E loops under 1 and 100 Hz are presented at various temperatures with an electric field amplitude of 2.5 MV m(-1). The indirect method based on the Maxwell relations is used to calculate the electrocaloric response. The result demonstrates that the electrocaloric responses based on the P-E loops measured at 1 Hz agree well with direct measurement results in the literature, but at 100 Hz, the coexistence of positive and negative electrocaloric effects (ECEs) is obtained, which has not been reported before. Domain switching is a dynamic process and rate-dependent, which has a significant influence on the polarization behavior and the subsequent electrocaloric performance of ferroelectric materials. The result also shows that during the indirect ECE evaluation, high attention needs to be paid to the applied electric field frequency to obtain accurate and comparable electrocaloric evaluations in ferroelectric materials.