Study the oxygen vacancies and Fe oxidation states in CaFeO3-δ perovskite nanomaterial

CaFeO3-δ perovskite nanomaterial has been synthesized by sol-gel method. Rietveld analysis of the X-Ray diffraction (XRD) data of the CaFeO3-δ sample revealed orthorhombic perovskite structure (space group pcmn). Field emission scanning electron microscope (FE-SEM) of the CaFeO3-δ sample showed the agglomerations of various particles. Mössbauer measurement of the CaFeO3-δ sample showed that the value of δ is 0.262 and Fe oxidation states are Fe3+ in octahedral and Fe4+ in tetrahedral coordination. X-ray photoelectron spectroscopy (XPS) revealed that the presence of Fe3+, Fe4+ ions, and oxygen vacancies at the surface of the CaFeO3-δ sample. Thermogravimetry analysis (TG) and differential scanning calorimetric (DSC) of the CaFeO3-δ sample revealed the presence of phase transitions. The magnetic properties of the CaFeO3-δ sample exhibit mainly antiferromagnetic state as confirmed by Mössbauer measurement. Based on the obtained results, the presence of oxygen vacancies and mixed oxidation states of iron (Fe3+ and Fe4+) makes the CaFeO3-δ sample useful for industrial applications.