FORMATION OF OXIDE PHASES IN THE SYSTEM FE2O3-NIO

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-degrees-C. X-ray diffraction showed the presence of alpha-Fe2O3, NiO and NiFe2O4 in samples prepared at 800-degrees-C. The oxide phases alpha-Fe2O3, NiO, NiFe2O4 and a phase with structure similar to NiFe2O4 were found in samples prepared at 1100-degrees-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 alpha-Fe2O3 prepared at 1100-degrees-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.