Improved multiferroic properties of La-doped 0.6BiFeO₃–0.4SrTiO₃ solid solution ceramics

The 0.6(Bi_1-xLa_x)FeO₃-0.4SrTiO₃ (x=0, 0.1) multiferroic ceramics are prepared by a modified Pechini method to study the effect of substitution of SrTiO₃ and La in BiFeO₃. The X-ray diffraction patterns confirm the single phase characteristics of all the compositions each with a rhombohedral structure. The magnetic properties of the ceramics are significantly improved by a solid solution with SrTiO₃ and substitution of La. The values of the dielectric constant ε_r and loss tangent tan δ of all the samples decrease with increasing frequency and become constant at room temperature. The La-doped 0.6BiFeO₃-0.4SrTiO₃ ceramics exhibit improved dielectric and ferroelectric properties, with higher dielectric constant enhanced remnant polarization (P_r) and lower leakage current at room temperature. Compared with a anti-ferromagnetic BiFeO₃ compound, the 0.6(Bi_0.9La_0.1)FeO₃-0.4SrTiO₃ sample shows the optimal ferromagnetism with remnant magnetization M_r～0.135 emμ/g and ferroelectricity with P_r～5.94 μC/cm² at room temperature.