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

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 × 10-6Km/V was found for x = 0.04, which significantly exceeds of values found so far in other lead-free electrocaloric materials.