Large electrocaloric effect in lead-free Ba(ZrxTi1-x)O3 thick film ceramics

Barium zirconate titanate (Ba(ZrxTi1-x)O3) thick film ceramics were prepared using a tape-casting method. Their structures, morphologies, and electric properties were characterized using XRD, SEM and impedance analysis approaches, respectively. The electrocaloric effects (ECE), i.e., isothermal entropy changes and adiabatic temperature changes, were calculated using a Maxwell relation. It was confirmed by XRD and SEM that the obtained thick film ceramics are pure and dense perovskite structures. The dielectric analyses indicate that the Ba(ZrxTi1-x)O3 thick film ceramics show characteristics of transition from normal to relaxor ferroelectrics with the increasing Zr4+ ionic content. The polarization - electric field (P-E) hysteresis loops reveal larger polarizations and the ceramics can withstand an electric field as high as 12 MV/m. The adiabatic temperature changes ΔT calculated via the Maxwell relation and the polarization as a function of temperature, which is extracted from the P-E hysteresis loops measured at 12 MV m−1 are from 3.7 to 0.28 K with the increasing Zr4+ ionic content.