High Curie Temperature BiFeO3-BaTiO3 Lead-free Piezoelectric Ceramics: Ga3+ Doping and Enhanced Insulation Properties

BiFeO3-BaTiO3 is a promising high-temperature lead-free piezo-ceramics due to its high Curie temperature (T-C > 500 degrees 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))Ga(x)O(3)-0.3BaTiO(3) (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 ( V (O) center dot center dot), 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 (d(33) = 174 pC N-1 and k(p) = 29%) and high Curie temperature (T-C = 497 degrees 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 V O center dot center dot appearance.