Electrocaloric effect of alkali co-substituted Sr0.6Ba0.4Nb2O6 ceramics

Abstract

We have investigated the electrocaloric properties of K+ and Na+ co-substituted Sr0.6Ba0.4Nb2O6 (SBN) ceramics using the indirect method. Tetragonal tungsten bronze (K0.5Na0.5)2x(Sr0.6Ba0.4)5-xNb10O30 (KNSBN) with x = 0.24 was synthesized using dual-step sintering. Despite the low amount, K+ and Na+ co-substitution resulted in normal ferroelectric behaviour, showing no significant shift in the dielectric maximum temperature of 111 °C with increasing frequency. Maximum electrocaloric temperature change (?T) of 0.3 K was observed at an electric field of 30 kV/cm (?E) yielding the largest electrocaloric responsivity (?T/?E) among SBN based ceramics. This relatively large value is in agreement with the larger pyroelectric coefficient of KNSBN compared to SBN based ceramics. © 2020 Elsevier B.V.