The improvement of piezoelectric properties in BiFeO3-BaTiO3 lead-free ceramics prepared with heat-treated rutile TiO2

BiFeO3-BaTiO3 lead-free piezoelectric ceramics have been studied for their application to sensors and actuators. The high strain and piezoelectric actuator coefficient (d(33)*) are observed in tetragonal 0.60BiFeO(3)-0.40BaTiO(3) ceramic with heat-treated single-phase rutile titanium dioxide (TiO2) powders than in ceramic with commercial mixed-phase with rutile and anatase TiO2. The optimized sintering temperature is 1010 degrees C with the quenching process. The increase of the grain size in microstructure, higher tetragonal phase volume fraction, and higher tetragonality are observed in ceramic with rutile TiO2 than in ceramic with commercial TiO2. The maximum strain is 0.316%, and d(33)* is 576 pm/V. A high Curie phase transition temperature of 355 degrees C is measured with the maximum dielectric constant (epsilon(r),(max)) about 30% higher than that of ceramic with commercial TiO2. It is found that the single-phase starting material is important to improve piezoelectric, ferroelectric, and dielectric properties in lead-free piezoelectric ceramics.