Sr doped BiMO 3 (M = Mn, Fe, Y) perovskites: Structure correlated thermal and electrical properties

Sr2+ substituted BiMnO3−δ (BSM), BiFeO3−δ (BSF) and BiYO3−δ (BSY) perovskites structured samples have been investigated for their structural, thermal and electrical properties. These samples are characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), iodometric titration, Raman spectroscopy, thermogravimetric analysis (TGA) and conductivity. Rietveld refinement confirms that BSY sample has cubic (Fm-3m) symmetry with limited solid solubility of Sr2+ as compared to tetragonal symmetry (p4mm) of BSM and BSF samples. X-ray photoelectron spectroscopy study confirms the presence of Mn4+ and Fe4+ content in BSM and BSF samples. The amount of Mn3+, Fe4+ and oxygen vacancies in these systems are calculated by iodometric titration. The highest oxygen vacancies are found in BSF sample. The BSM system exhibit the highest conductivity followed by BSF and BSY samples due to the presence of Mn4+ content and moderate oxygen vacancies in this particular sample.