Electrocaloric effect and freezing temperature in(Pb_(0.8)Ba_(0.2))[(Zn_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)]O_(3) relaxor ferroelectric ceramic

The electrocaloric effect(ECE)is studied in(Pb_(0.8)Ba_(0.2))[(Zn_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)]O_(3) relaxor ferroelectric ceramic by using an“indirect method”.The electric dependence for the polarization(hysteresis loops)has been obtained for several temperatures showing typical relaxor characteristics.The temperature change△T,which is associated with the ECE,is calculated by using the temperature dependence for the polarization.A maximum value for△T is observed for temperatures close above the freezing temperature,showing an indirect evidence of that critical temperature.The results are discussed considering the contribution of the polar nanoregions to the polarization.