Enhanced electrocaloric strengths at room temperature in (SrxBa1−x)(Sn0.05Ti0.95)O3 lead-free ceramics

The electrocaloric effect (ECE) in lead-free (Ba 1−x Sr x )(Sn 0.05 Ti 0.95 )O 3 (BSSnT) (x = 0.05, 0.10, 0.15, 0.20) ceramics were investigated around room temperature using direct and indirect approaches. Results indicate that the maximum ECE occurs near the Curie temperature and slightly shifts towards high temperatures with the increasing applied electric field. The directly measured ECE is larger than that calculated using the Maxwell relation. The maximum electrocaloric strength ΔT/ΔE = 0.52 × 10 −6 K m/V was obtained at T = 36 °C, with an adiabatic ΔT of 1.05 °C at 2 MV m −1 . An analytic formula of electrocaloric strength (dT/dE) was deduced, via which the maximum dT/dE was estimated. The factors affecting the electrocaloric strength were discussed, and the experimental results were compared with those derived from the formula.