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

0.725 BiFe 1− x Sc x O 3 –0.275 BaTiO 3 + y mol% MnO 2 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°C–990°C and possess a pure perovskite structure. The ceramics with x / y = 0.01–0.02/1.0 sintered at 960°C possess high resistivity (~2 × 10 9 Ω·cm), strong ferroelectricity ( P r = 19.1–20.4 μm/cm 2 ), good piezoelectric properties ( d 33 = 127–128 pC/N, k p = 36.6%–36.9%), and very high Curie temperature (618°C–636°C). The increase in sintering temperature improves the densification, electric insulation, ferroelectric, and piezoelectric properties of the ceramics. A small amount of Sc doping ( x ≤ 0.04) and the increase in the sintering temperature significantly enhance the ferromagnetic properties of the ceramics. Improved ferromagnetism with remnant magnetization M r of 0.059 and 0.10 emu/g and coercive field H c of 2.51 and 2.76 kOe are obtained in the ceramics with x / y = 0.04/1.0 (sintered at 960°C) and 0.02/1.0 (sintered at 1050°C), respectively. Because of the high T C (636°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 MnO 2 is essential to obtain the ceramics with good electrical properties and electric insulation.