Composition induced structural transition and improved magnetic behavior in La substituted BiFeO₃ compound

We present a detailed study on the structural, electronic, magnetic and dielectric properties of La substituted multiferroic bismuth ferrite. Polycrystalline Bi_1 − xLa_xFeO₃ (0.1 ≤ x ≤ 0.3) samples were prepared by conventional solid state reaction method. The Rietveld refinement of x-ray diffraction data and Raman spectroscopy study showed clear indication of emergence of orthorhombic phase. Significant improvement in magnetic properties has been observed owing to the rhombohedral (R3c) to orthorhombic (Pnma) structural transition for 30 mol% La substituted sample. The x-ray photoelectron spectroscopy study confirmed the absence of mixed valency or detectable vacancies. Therefore, the increase in magnetization is the attribute of structural variance. The dielectric behavior showed initial increase in permittivity with La substitution but further decrease with structural change.