Sol–gel synthesis, characterization and dielectric properties of Bi1−x La x FeO3

Abstract

Bi1−x La x FeO3 (x = 0.05, 0.1, 0.15 and 0.2) powders and ceramics were prepared by a polyvinyl alcohol (PVA) sol–gel route. Differential scanning calorimetry and thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy and environmental scanning electron microscope were used to characterize the precursors, the derived oxide powders and sintered ceramics. Single-phase Bi1−x La x FeO3 powders were obtained at a temperature as low as 500 °C for 2 h, without the formation of any intermediate phase. All samples were found to be rhombohedrally distorted perovskite structure with a space group of R3c. The effect of La substitution on the dielectric properties of Bi1−x La x FeO3 ceramics was studied over the frequency range of 10 kHz–1 MHz. The real part of permittivity of Bi1−x La x FeO3 samples decreased with the increase of La content. The remnant magnetization M r and coercive field H c increase with La doping content. A H c of as high as 2 × 106 A/m was obtained for Bi0.8La0.2FeO3.