Effects of Long- and Short-Range Ferroelectric Order on the Electrocaloric Effect in Relaxor Ferroelectric Ceramics

Relaxor ferroelectrics continue to attract great attention for applications, including electrocaloric refrigeration, but the commonly used, indirect method of electrocaloric characterization based on the Maxwell relation often leads to artifacts. This analysis of long- and short-range ferroelectric order and the electrocaloric effect in Pb${}_{0.91}$La${}_{0.06}$Zr${}_{0.8}$Ti${}_{0.2}$O${}_{3}$ uses both direct and indirect characterizations, to clarify the applicability of the Maxwell relation to the physics of the relaxor, and the origin of discrepancies. It also suggests how to design relaxors with large electrocaloric effect by exploiting the transitions between polar nanoregions.