Microstructure, Ferroelectric, Piezoelectric, and Ferromagnetic Properties of Sc-Modified BiFeO3-BaTiO3 Multiferroic Ceramics with MnO2 Addition

0.725BiFe(1-x)Sc(x)O(3)-0.275BaTiO(3)(+) ymol% MnO2 multiferroic ceramics were fabricated by a conventional ceramic technique and the effects of Sc doping and sintering temperature on microstructure, multiferroic, and piezoelectric properties of the ceramics were studied. The ceramics can be well sintered at the wide low sintering temperature range 930 degrees C-990 degrees C and possess a pure perovskite structure. The ceramics with x/y=0.01-0.02/1.0 sintered at 960 degrees C possess high resistivity (similar to 2x109 center dot cm), strong ferroelectricity (Pr=19.1-20.4m/cm2), good piezoelectric properties (d33=127-128pC/N, kp=36.6%-36.9%), and very high Curie temperature (618 degrees C-636 degrees C). The increase in sintering temperature improves the densification, electric insulation, ferroelectric, and piezoelectric properties of the ceramics. A small amount of Sc doping (x0.04) and the increase in the sintering temperature significantly enhance the ferromagnetic properties of the ceramics. Improved ferromagnetism with remnant magnetization Mr of 0.059 and 0.10emu/g and coercive field Hc of 2.51 and 2.76kOe are obtained in the ceramics with x/y=0.04/1.0 (sintered at 960 degrees C) and 0.02/1.0 (sintered at 1050 degrees C), respectively. Because of the high TC (636 degrees C), the ceramic with x/y=0.02/1.0 shows good temperature stability of piezoelectric properties. Our results also show that the addition of MnO2 is essential to obtain the ceramics with good electrical properties and electric insulation.