Piezoelectric properties of Mn-doped 0.75BiFeO 3 –0.25BaTiO 3 ceramics

Abstract The effects of Mn doping were investigated in 0.75BiFeO 3 –0.25BaTiO 3 ceramics sintered at 940–1020 °C in air. 0.75BF–0.25BT ceramics doped with 0–0.7 wt% MnO 2 were prepared by a conventional ceramic process. The effects of the doping are strongly dependent on the sintering temperature and doping concentration. MnO 2 doping at less than the solubility limit of 0.5 wt% suppressed the formation of large pores during the sintering, and kept the sample dense at high sintering temperatures. The onset temperature of abrupt grain growth also increased. The piezoelectric properties were poor when the grain size was about 1 µm or less, but showed a significant increase in samples with grain size greater than a few micrometers, independent of the Mn doping concentration. The piezoelectric properties are more strongly influenced by the grain size than the Mn doping.