Physicochemical properties of solid–solid interactions in nanosized NiO-substituted Fe2O3/TiO2 system at 1200°C

An equimolar mixture of Fe2O3 and TiO2, and a series of mixtures in which TiO2 was progressively replaced with NiO, were prepared by ball milling aqueous suspensions. Dried and pressed specimens were sintered at 1200 C for 4 h. The sintered, undoped specimen consisted of nanocrystalline Fe2TiO5, and exhibited very low saturation magnetic flux density (Bs), remanent magnetic flux density (Br) and energy (BH)max. NiO substitution resulted in the formation of nanosized phases of NiTiO3 and NiFe2O4, with the NiTiO3 content increasing for substitutions up to 0.6, then decreasing to zero at a substitution level of 0.8. The NiFe2O4 content decreased and the Fe2TiO5 content decreased with increasing substitution. The Bs, Br and (BH)max values were significantly enhanced by the substitution. The specimens catalysed the decomposition of hydrogen peroxide, the rate constant increasing with increasing degree of substitution. 32 refs.