Electrocaloric Effects in Some Ferroelectric and Antiferroelectric Pb(Zr, Ti)O3 Compounds

Variations of sample temperature arising from the electrocaloric effect, antiferroelectric to ferroelectric transitions, and hysteresis-loss heating have been recorded together with the hysteresis loops for four different ceramic ferroelectrics near room temperature. Both the electric-field dependence and the temperature dependence of the electrocaloric effect were accurately predicted by the usual thermodynamic expression for the effect. Values for the heat capacity and the pyroelectric constant were also obtained from the data. The sample temperature of one composition which becomes antiferroelectric under zero applied field near 40°C was monitored at various temperatures as antiferroelectric to ferroelectric transitions were forced by an electric field. Above 55°C, the temperature change at the transition could be fitted with a theory originally developed for the field-enforced antiferroelectric to ferroelectric transition in PbZrO3.