Phase structure, piezoelectric and multiferroic properties of SmCoO3-modified BiFeO3-BaTiO3 lead-free ceramics

(0.75-x)BiFeO3-0.25BaTiO(3)-xSmCoO(3) + 1 mol.% MnO2 lead-free multiferroic ceramics were synthesized by a conventional ceramic fabrication technique. The effects of SmCoO3 on phase structure, piezoelectricity and multiferroicity of the ceramics were studied. All the ceramics can be well sintered at a low sintering temperature of 960A degrees C. The crystalline structure of the ceramics is transformed from rhombohedral to tetragonal symmetry with increasing the amount of SmCoO3. A morphotropic phase boundary of rhombohedral and tetragonal phases is formed at x = 0.01-0.04. A small amount of SmCoO3 is shown to improve the ferroelectric, piezoelectric and magnetoelectric properties of the ceramics. For the ceramics with x = 0.01-0.03, enhanced resistivity (R 1.2 x 10(9) Omega cm to 2.1 x 10(9) Omega cm), piezoelectricity (d (33) 65 pC/N to 106 pC/N) and ferroelectricity (P (r) 6.38 mu C/cm(2) to 22.89 mu C/cm(2)) are obtained. The ferromagnetism of the materials is greatly enhanced by the doping of SmCoO3 such that a very high magnetoelectric coefficient of 742 mV/(cm Oe) is obtained at x = 0.01, suggesting a promising potential in multiferroic devices.