Gadolinium-Nickel ferrites prepared from metal citrates precursors

The structure of a series of nickel ferrites obtained from mixed Gd, Fe and Ni citrates has been investigated in order to explore the possibility of Gd-for-Fe substitution in the solids. Five samples with nominal composition NiFe2.00-yGdyO4,y=0.00, 0.04, 0.05, 0.10 and 0.12, were prepared by the auto-combustion method. For y<>0, a mixture of a substituted ferrite, GdFeO3, and variable quantities of NiO composes the obtained solids. Rietveld simulation and Mossbauer spectra confirm the Gd-for-Fe substitution in the spinel phase. Ferrite-cell parameter indicates that the maximum Gd-for-Fe substitution is accomplished at y=0.05. Electromagnetic measurements indicate an enhancement of the permeability for the Gd-inserted samples