Superior high-temperature piezoelectric response of lead-free Ga-doped BiFeO3−BaTiO3 ceramic with multiphase coexistence

Abstract

Herein, the (1 − x)BiFe0.97Ga0.03O3 − xBaTiO3 (BF97BG3 − xBT) ceramics were prepared by modulating the content of BT using (Bi0.5Li0.5)TiO3 and MnO2 as sintering additives. A record d33 of 533.2 pC/N is achieved in the BF97BG3 − 0.34BT ceramic at a real-time depolarization temperature (Tdr) of 314.7 °C, indicating the piezoelectric characteristic in the actual operating state. A multiphase coexistence structure involving rhombohedral (R), tetragonal (T), cubic (C) phases is produced in the BF97BG3-0.34BT ceramic, which contributes to the large piezoelectric response. The in-situ X-ray diffraction (XRD) results demonstrate that the crystal structure of BF97BG3-0.34BT ceramic does not change with the increase of temperature. Moreover, the formation of nanodomain morphology and a large number of polar nanoregions (PNRs) can weaken the energy barrier and polarization anisotropy, enhance the polarization rotation, and thus improve the piezoelectric response of the ceramic. This work provides an effective strategy to achieve large high-temperature piezoelectric response by constructing nanoscale multiphase coexistence.