High Curie temperature BiFeO3-BaTiO3 lead-free piezoelectric ceramics: Ga3+ doping and enhanced insulation properties

Abstract

BiFeO3-BaTiO3 is a promising high-temperature lead-free piezo-ceramics due to its high Curie temperature (TC>500°C) and excellent piezoelectric properties. However, a high leakage current was often detected in this system, which severely affects its applications. In this work, the 0.7BiFe(1−x)GaxO3-0.3BaTiO3 (BFGax-BT, 0.00≤ x≤ 0.10) system was designed to reveal the reason of leakage-current density decreased by their leakage mechanism. Because of the suppression of generation of Fe2+ and oxygen vacancy, the leakage mechanism from space charge limited conduction mechanism found in Ga-free BF-BT ceramics turns into Ohmic conduction and Schottky emission mechanism as Fe3+ was replaced with Ga3+. A good combination of piezoelectric properties (d33=174 pC N−1 and kp=29%) and high Curie temperature (TC=497°C) was achieved in the BFGa0.06-BT ceramic owning the lowest leakage-current density. This work will provide the clues for preparing the high insulation and high piezoelectric performance BF-BT-based ceramics by suppressing the valence change of Fe3+ and appearance.