Electric-field-induced dielectric and temperature changes in a⟨011⟩-orientedPb(Mg1/3Nb2/3)O3-PbTiO3single crystal

Abstract

Dielectric and direct temperature changes induced by an electric field were investigated in a $⟨011⟩$-oriented $0.72\text{Pb}({\text{Mg}}_{1/3}{\text{Nb}}_{2/3}){\text{O}}_{3}\text{\ensuremath{-}}0.28{\text{PbTiO}}_{3}$ single crystal as a function of temperature. Field-induced temperature changes were measured directly from the surface of the crystal by a thermocouple. Three distinct anomalies at temperatures of $\ensuremath{\sim}68$, $\ensuremath{\sim}96$, and $\ensuremath{\sim}128\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$ were identified in the dielectric and temperature change responses of the crystal, dividing the temperature range into four distinct phase stability regions with different field-induced behaviors. Just above the depolarization temperature of $128\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$, dielectric hysteresis showed a double-loop nature caused by a reversible nonpolar-polar phase transition accompanied by an increase in the electrocaloric temperature change. Two other reversible field-induced phase transitions with different field-induced thermal behaviors were evidenced in the polarization and temperature responses in the temperature ranges of $96--128\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$ and below $68\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$.