Giant electrocaloric effect and high-field electrostrictive properties in Ba(Ti1−xSnx)O3 ceramics

Abstract

One of the emerging solid-state refrigeration technologies to replace classic compression refrigeration is electrocaloric refrigeration, which has the advantages of high energy conversion efficiency, easy miniaturization, eco-friendliness, and low cost. In this paper, Ba(Ti1−xSnx)O3 (BTSn) ceramics with x = 0.02–0.08 were prepared by a solid-state reaction route. The structural, dielectric, ferroelectric, electrocaloric as well as electrostrictive characteristics were thoroughly examined. Our results show that the dielectric peaks correlated to the maximal permittivity move towards to low temperature direction when the Sn4+ concentration gradually increases, and a phase diagram of BTSn based on the dielectric characteristics is given. More importantly, in the x = 0.04 ceramic sample synthesized by the viscous polymer process, a giant adiabatic temperature change (ΔT) of 6.36 K with a temperature range of 25 °C at 200 kV/cm is achieved. Typically flare shape electrostrain curves accompanying with small hysteresis are observed in all studied compositions. The average electrostrictive coefficient Q33 varies within 0.0257–0.0306 m4/C2 at a temperature region from 30 to 160 °C, indicating temperature-insensitive and composition-insensitive characteristics. This research shows that a significant electrocaloric effect can be achieved in BTSn ceramics through high electric field, and would provide a strategy for boosting the electrocaloric effect in other systems.