Enhanced piezoelectric and ferroelectric properties of tetragonal BiFeO3–BaTiO3 ceramics via tailoring sintering temperature and dwell time

The enhanced piezoelectric and ferroelectric properties of the tetragonal 0.67BiFeO3–0.33BaTiO3 (BF–33BT) ceramics without MnO2 doping or other dopants via tailoring sintering temperature (TS) and dwell time (td) are reported. All ceramics crystallized in a single tetragonal phase, independent of the adopted TS and td. As the TS or td is increased, the BF–33BT ceramics show an increase in grain size and in relative density, while TS > 980 °C or td > 6 h would result in more oxygen vacancies caused by Bi3+ evaporation and/or reduction of Fe3+ to Fe2+, along with a reduced relative density and an increased current leakage density. Because of the increased grain size, the higher relative density, and relatively less oxygen vacancies, high d33 = 151 pC/N and Pr = 25.9 μC/cm2 were achieved in tetragonal BF–33BT ceramics with TS = 980 °C and td = 6 h. In addition, large unipolar strain of 0.146% and $$d_{33}^{*}$$ =326 pm/V (40 kV/cm), as well as high TC = 427 °C were also obtained in the BF–33BT ceramics with TS = 980 °C and td = 6 h. Our studies indicate that the grain size, the relative density, and the oxygen vacancies play important roles for the piezoelectric properties of BF–33BT ceramics.