High-Temperature Stable Piezoelectricity in BiFeO_3-Based Lead-Free Ceramics

The bismuth ferrite (BiFeO₃)-based perovskite ferroelectric, possesses strong spontaneous polarization and high Curie temperature, is considered as one of the alternatives to lead zirconate titanate. However, the low piezoelectricity and poor temperature stability seriously hinders its application. Here, we significantly improve electrical properties in BiFeO₃-BaTiO₃ ceramic by judicious introduction of dopants. We can achieve high piezoelectric coefficient d₃₃ of 175 pC N^-1 at room temperature, and d₃₃ has no obvious decay until the temperature near 350 °C. The results indicate that the improved piezoelectricity can be attributed to the enhanced symmetry of the crystal structure and decreased domain size. The enhanced thermal stability of the d₃₃ is related to the charge compensation and stable crystal structure. This work will be of great significance to the lead-free development of piezoelectric materials.