Evolution behavior of electrocaloric effect in BaTiO3‐based ceramics with different phase structures and phase transitions

Abstract In this work, the evolution behavior of electrocaloric effect in BaTiO 3 ‐based ceramics with different phase structures and phase transitions was compared. A paradigmatic system of (Ba 0.85 Ca 0.15 )(Ti 1− x Hf x )O 3 ceramics was selected. Diffuseness exponent γ increases linearly with rising x . Electrocaloric temperature change (Δ T ) shows an opposite variation, whereas temperature span ( T span ) displays the same tendency with γ changing. The degeneration of maximum polarization and polarization change rate contributes to the decrease in Δ T due to the diffusion phase transition, whereas the diffusion can lead to a large T span . The ceramic with a single ferroelectric or paraelectric phase shows a small Δ T but a high variation rate with elevating electric field ( E ), whereas a small variation rate is present in the phase‐transition region that shows a high Δ T . Besides, small electrocaloric strength (Δ T /Δ E ) is obtained in the single‐phase region and increases with elevating E . A high Δ T /Δ E is present in the phase‐transition region but decreases with elevating E . When phase transition becomes diffusion, Δ T variation with E becomes obvious, whereas Δ T /Δ E dependence will decrease. These phenomena result from the difficult polarization orientation in single ferroelectric phase or weak polarization in paraelectric phase, and the easy polarization orientation in the phase‐transition region.