Large electrocaloric effect in tetragonal perovskite 0.03Bi(Mg1/2Ti1/2)O3–0.97(0.875Bi1/2Na1/2TiO3–0.125BaTiO3) lead-free ferroelectric ceramics

摘要： In this work, we reported a large electrocaloric effect (ECE) in tetragonal perovskite 0.03 Bi(Mg1/2Ti1/2)O3–0.97 (0.875Bi1/2Na1/2TiO3–0.125BaTiO3) ceramic. It was found that the composition demonstrates a coexisting state of the ferroelectric P4mm and relaxor P4bm. Due to the ?eld-induced phase transition from relaxor with P4bm symmetry to ferroelectric with P4mm symmetry, a positive ECE is observed in the temperature range of 25–130 °C. Under an electric ?eld of 4 kV/mm, a large temperature change ΔT of 0.75 °C was achieved at 80 °C, and the EC responsivity ΔTmax/ΔE of 0.19 K·cm/kV, indicating a promising lead-free material for potential application in solid-state refrigerators.