Piezoelectric Properties of BiFeO3 Exposed to High Temperatures

BiFeO3 is a ferroelectric with a Curie temperature of 830 °C, however, its piezoelectric performance at high temperature remains unclear. The current work reveals a disappearance/recovery of piezoelectricity in BiFeO3 at elevated temperature and upon cooling. In particular, that temperature is strongly frequency‐dependent and ranges from 280 to 430 °C between 0.5 and 140 Hz, respectively. Meanwhile, in situ and ex situ X‐ray diffraction and piezoresponse microscope analysis demonstrate thermally‐resistant domain texture to temperatures as high as 750 °C. This demonstrates that the piezoelectricity of BiFeO3 is strongly influenced by its resistance/conductance variations due to charge carrier motion limiting the operational frequency. The investigation enhances the understanding of BiFeO3 complex piezoelectric behavior at various temperatures, offering insights into its potential applications. BiFeO3 lead‐free ceramics exhibit a disappearance of piezoelectricity in BiFeO3 upon heating to ≈300–450 °C, and this temperature increases with increasing measuring frequency. Remarkably, the piezoelectricity recovers upon cooling. These behaviors are attributed to its significant electrical leakage but outstanding thermal resistance of its poled state to very high temperature approaching its Curie point of 830 °C.