Mössbauer, Infrared and X-ray Studies for Ni0.5Zn0.5CrxFe2-xO4 Ferrites

Authors : Mohamed AMER, Samy ATAALLAH, Talaat MEAZ, Saad ABOULENEIN

Pages : 163-177

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Spinel ferrites of the system Ni0.5Zn0.5CrxFe2-xO4, 0 \le x \le 1, have been studied via Mössbauer, IR and X-ray spectra. Mössbauer spectra of the samples showed broad six-line patterns and a central paramagnetic phase. The spectra have been analyzed to two magnetic patterns, A and B, and two quadrupole doublets, CA and CB. The patterns A and CA are assigned to Fe3+ ions at the tetrahedral A-sites and the patterns B and CB to Fe3+ and Fe2+ ions at the octahedral B-sites. The deduced hyperfine interaction parameters; the isomer shifts, quadrupole splitting, outermost line widths, hyperfine magnetic fields and bulk magnetization were studied and discussed as functions of the Cr3+ additions x. The cation distribution of the compounds was estimated using the site preference of elements and the area ratio of B- to A-sites. The broad magnetic pattern B has been fitted to several subpatterns. Using the obtained hyperfine parameters one could assign each of the B-subpatterns to a component depends on the number of nonmagnetic Zn2+ ions as A-site nearest neighbours of the Fe ions at the B-sites. Five absorption bands were observed in the infrared spectra in the range between 1100 and 200 cm-1. These bands are assigned to the Fe3+ ions on A-sites; to Fe3+ and Cr3+ ions on B-sites; to divalent ions Fe2+ and Ni2+ and to the energy of the lattices. The existence of Fe2 ions on the A- and B-sites has been confirmed. From X-ray analysis, the average, true, and theoretical lattice parameters, the theoretical and bulk densities, the porosity, the oxygen parameter and the ionic radii, bonds, edges and hopping lengths of the A- and B-sites have been calculated and discussed depending on the Cr3+ ion content x. The dependency of the hyperfine field on the hopping length at the A- and B-sites has been studied and discussed.
Keywords : Mössbauer, Infrared, X ray and ferrites