Piezoelectric properties and temperature stabilities of Mn- and Cu-modified BiFeO3–BaTiO3 high temperature ceramics

The structures, microstructures, electrical properties and the thermal stability have been investigated for the MnO2-doped (1 − x)BF–xBT system and the MnO2 and CuO-doped (1 − x)BF–xBT system, where x ranges from 0.25 to 0.35. The XRD analysis shows that the two systems have a single perovskite phase, and the MnO2 and CuO-doped (1 − x)BF–xBT system has a morphotropic phase boundary (MPB) with the coexistence of rhombohedral and pseudo-cubic phases in the system about x = 0.325. The addition of small amount of CuO was quite effective to lower the sintering temperature. The diffusive phase transition characteristics were observed in the MnO2-doped (1 − x)BF–xBT system and a normal ferroelectric phase transition characteristics were observed in the MnO2 and CuO doped (1 − x)BF–xBT system. Compared with the MnO2 doped (1 − x)BF–xBT system, the ɛm, Curie temperature (Tc), depoling temperature (Td), and piezoelectrical properties were improved evidently with the MnO2 and CuO doping.