Formation of oxide phases in the system Fe₂O₃-NiO

Abstract

Mixed metal oxides in the system Fe₂O₃-NiO were prepared by coprecipitation of Fe(OH)₃/Ni(OH)₂ and the thermal treatment of hydroxide coprecipitates up to 800 or 1100°C. X-ray diffraction showed the presence of α-Fe₂O₃, NiO and NiFe₂O₄ in samples prepared at 800°C. The oxide phases α-Fe₂O₃, NiO, NiFe₂O₄ and a phase with structure similar to NiFe₂O₄ were found in samples prepared at 1100°C. Fourier transform-infrared spectra of oxide phases formed in the system Fe₂O₃-NiO are discussed. Two very strong infrared bands at 553 and 475 cm⁻¹, a weak intensity infrared band at 383 cm⁻¹ and two shoulders at 626 and 441 cm⁻¹ were observed for α-Fe₂O₃ prepared at 1100°C. NiFe₂O₄, prepared at the same temperature, showed two broad and very strong infrared bands at 602 and 411 cm⁻¹, while NiO showed a broad infrared band at 466 cm⁻¹. Fourier transform infrared spectroscopic results were in agreement with X-ray diffraction.