Lead-free Ba0.8Ca0.2(ZrxTi1−x)O3 ceramics with large electrocaloric effect

Abstract

The electrocaloric effect was investigated in lead-free Zr doped Ba0.8Ca0.2(ZrxTi1−x)O3 (BCTZ) ceramics synthesized by a conventional sintering process. Room-temperature x-ray diffraction analysis showed that the tetragonal structure is obtained in BCTZ for x ≤ 0.08 and a pseudo cubic phase for x > 0.08. The dielectric spectroscopy and calorimetry revealed that the Curie temperature decreases as a consequence of Zr doping and that the BCTZ exhibits a first order ferroelectric phase transition. The electrocaloric effect was determined by the calculation of the electrocaloric change of temperature (ΔT) using the Maxwell relation based on the P–E hysteresis loops measured at different temperatures. A large electrocaloric responsivity ΔT/ΔE = 0.34 × 10−6 Km/V was found for x = 0.04, which significantly exceeds of values found so far in other lead-free electrocaloric materials.