Structure, ferroelectric, ferromagnetic, and piezoelectric properties of Al-modified BiFeO3-BaTiO3 multiferroic ceramics

0.725BiFe(1-x)Al(x)O(3)-0.275BaTiO(3) + 1 mol% MnO2 ceramics were prepared by a conventional ceramic technique. The effects of Al doping and sintering temperature on microstructure, piezoelectricity and magnetism of the ceramics were studied. The crystalline structures of BFO-BT-BA-x ceramics sintered at 970 degrees C for 2 h evolve from rhombohedral structure at x = 0 to the coexistence of rhombohedral structure and orthorhombic phases at x = 0.01-0.03 and finally to orthorhombic phases at x> 0.03. The critical sintering temperature is 970 degrees C. For the ceramics with x = 0.01 sintered at/above 970 degrees C, large grains, good densification, high resistivity, and enhanced ferromagnetic properties are obtained. The ceramic with x = 0.01 sintered at 970 8C possesses high resistivity (similar to 10(9) Omega cm) and good piezoelectric properties (d(33) = 138 pCN(-1), k(p) = 32.7%). Al doping decreases the ferromagnetic properties of the ceramics, while the increase in the sintering temperature enhances the ferromagnetic properties of the ceramics. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim