Negative/positive electrocaloric effect in antiferroelectric squaric acid

Using the previously developed model, we study the electrocaloric effect (ECE) in antiferroelectric crystals of squaric acid, where the low-temperature polarization reorientation by the external electric field has been earlier predicted to be a two-stage process with the intermediate ferrielectric phase. The T- E landscape of the model entropy is explored. The ECE, characterized by the electric Gruneisen parameter, is found to be negative in the antiferroelectric phase. In the ferrielectric phase, it is positive at low fields but becomes slightly negative below the transition to the ferroelectric phase. In the ferroelectric phase, the ECE is positive at all temperatures and fields. The negative EC temperature shift Delta T of the largest magnitude is predicted to be around - 2.7 K at 200 kV/cm. The supercritical behavior of the Gruneisen parameter in the crossover region between two bicritical end points is studied.

Automated summary

Using a previously developed model, the study explores the electrocaloric effect (ECE) in antiferroelectric crystals of squaric acid, which undergoes a two-stage process with an intermediate ferrielectric phase during low-temperature polarization reorientation induced by an external electric field. The T-E landscape of the model entropy is analyzed. The ECE is found to be negative in the antiferroelectric phase, positive at low fields in the ferrielectric phase, and positive at all temperatures and fields in the ferroelectric phase. A negative EC temperature shift ΔT of approximately -2.7 K at 200 kV/cm is predicted. The supercritical behavior of the Gruneisen parameter in the crossover region between two bicritical end points is also studied.