Combined effects of diffuse phase transition and microstructure on the electrocaloric effect in Ba1−xSrxTiO3 ceramics

This paper demonstrates the combined effects of diffuse phase transition and microstructure on the electrocaloric effect (ECE) in Ba1−xSrxTiO3 (x = 0.2–0.4) ferroelectric ceramics. The ECE was characterized by direct heat flow measurement and an indirect thermodynamic method, which both provided consistent results. With increasing amount of Sr, the phase transition diffused and the grains grew larger. Since larger grains favor a high ΔTmax while a diffuse phase transition does not, the combination of these two effects induced nonmonotonic variation of the ECE. The x = 0.35 sample showed the best performance, with an ECE strength of 0.23 K·m/MV near room temperature.