Large electrocaloric effects in PST multilayer capacitors over a wide range of temperatures including room temperature

Electric field-driven ferroelectric phase transitions result in thermal changes known as electrocaloric effects. Large electrocaloric effects arise in thin films because breakdown fields are large, and when many thin films are combined into a multilayer capacitor (MLC) then one has a macroscopic working body for pumping heat in a prototype cooling device. I will describe electrocaloric MLCs of PbSc_0.5Ta_0.5O₃ (PST) that outperform the Gd working bodies in magnetocaloric prototypes. These MLCs display large voltage-driven changes of temperature (up to 5.5 K) over a wide range of starting temperatures (over 3 K across 176 K) [Nature 575 (2019) 468]. I will also highlight other recent work: electrocaloric cooling cycles with true regenation via field variation [PRX 9 (2019) 041002]; quasi-indirect measurements of electrocaloric temperature change via comparison of adiabatic and isothermal electrical polarization data [APL Materials 9 (2021) 010701]; and a review article on magnetocaloric, electrocaloric and mechanocaloric effects [Science 370 (2020) 797].