Pseudo-first-order phase transition for ultrahigh positive/negative electrocaloric effects in perovskite ferroelectrics

The electrocaloric effect of ferroelectric materials, which occurs significantly near the first-order paraelectric/ferroelectric transition (FOPFT) Curie temperature, has tremendous prospect in solid-state cooling devices. In the present work, thermodynamics analysis and phase field simulations were conducted to demonstrate the mechanical compression-induced two types of pseudo-first-order phase transition, which could occur at a temperature below the Curie temperature. Thus, in one material there may coexist ultrahigh positive and negative electrocaloric effects, which are associated with the two pseudo-first-order phase transitions and tunable by the magnitude of the compression. The mechanical compression-induced pseudo-first-order phase transition and the coexistence of positive and negative electrocaloric effects will facilitate the development of a novel technology to design and manufacture next generation of solid-state cooling devices.