Indirect Electrocaloric Evaluation: Influence of Polarization Hysteresis Measurement Frequency

Abstract

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 À1 . 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.

Effect of Composition on Polarization Hysteresis and Energy Storage Ability of P(VDF-TrFE-CFE) Relaxor Terpolymers

“…From this equation, it is obvious that a positive temperature derivative of polarization implies a negative electrocaloric effect, as was reported by some groups [29][30][31]. While the direct electrocaloric measurements of similar compositions only show a positive electrocaloric effect [38,39].…”

“…In the case of polymers, this leakage current can be related to the field-induced transport of electronic and ionic charges. In some publications, this increase in the extrinsic polarization was considered as a signature of a negative electrocaloric effect (ECE) [29][30][31]. We have taken a detailed look at the polarization curves shown in Figure 4 to evaluate the critical fields corresponding to the transition to the ferroelectric state, E 1 , and back to the relaxor state, E 2 .…”

“…In the case of polymers, this leakage current can be related to the field-induced transport of electronic and ionic charges. In some publications, this increase in the extrinsic polarization was considered as a signature of a negative electrocaloric effect (ECE) [29][30][31].…”

Enhanced dielectric and electrocaloric properties in lead-free rod-like BCZT ceramics

“…[25]. The same frequency (1 Hz) was kept to avoid any influence of the frequency as reported by Cheng et al [53]. With increasing the temperature, the remnant polarization decreases continuously due to the disappearance of ferroelectric domains [54].…”

A Review of a Good Binary Ferroelectric Ceramic: BaTiO3–BiFeO3

“…Many approaches are used to measure the pyroelectric coefficient, including the direct method and the indirect methods. 29,34 Overall, the ferroelectric hysteresis loop is a key characteristic of the ferroelectric. It provides us with an intuitive experience of ferroelectric materials.…”