Domain evolution during electric poling and thermal depoling processes in lead-free 0.75BiFeO3-0.25BaTiO3 ceramics

Abstract

0.75BiFeO3-0.25BaTiO3 (0.75BF-0.25BT) ceramics have been widely studied because of their high Curie temperature, good thermal stability and lead-free trait. The evolution of domain motion during electric poling and thermal depoling processes is closely related to the piezoelectric properties and thermal stability of ferroelectric ceramics. Herein, the non-180° domain reversals of 0.75BF-0.25BT ceramics in these two processes were investigated by an in situ XRD technique. The non-180° domain switching fraction during the poling and depoling processes was calculated quantitatively based on the (111) and (111‾) diffraction peaks. During the poling process, the non-180° domain reversal percentage N111 and piezoelectric properties increase abruptly when the poling field exceeds 35 kV/cm and then saturate at the electric field of 50 kV/cm (N111 reaches the maximum value of 59%). The domains switched under the poling electric field of 50 kV/cm are stable below 500 °C. The depoling temperature is sensitive to the domain switching fraction under different poling electric fields, and the ceramics under a strong poling field possess excellent thermal stability and high depolarization temperatures. This work revealed the relationship between the electric properties, domain switching, poling electric field, and depoling temperature in the 0.75BF-0.25BT ceramics, which may pave the way to enhancing the room temperature piezoelectric properties and their thermal stability.