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

The bismuth ferrite (BiFeO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>)-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 BiFeO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>-BaTiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> ceramic by judicious introduction of dopants. We can achieve high piezoelectric coefficient d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</inf> of 175 pC N<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> at room temperature, and d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</inf> 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 d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</inf> 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.