Infrared Spectral Studies of Nanostructured Co2+ -Substituted Li-Ni-Zn Ferrites

Polycrystalline Li(0.5)Ni(0.25-0.5)xCo(0.5)xZn(0.5)Fe(2)O(4) ferrites (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared by standard auto-ombustion method and characterized by XRD and IR spectra. The XRD results suggest that all samples were single-hase with a cubic spinel-ype structure. The lattice constant, particle size, metal-oxygen bond length (R-A and R-B), cation radii (r(A) and r(B)) on A and B-sub lattices were found to increase while the X-ay density and porosity, decrease with increasing x. The IR spectra show two absorption bands, at.1 about 600 cm(-1) and v(2) at about 425 cm(-1), which were attributed to tetrahedral ( A) and octahedral ( B) sites of the spinel structure, respectively. The band positions were found to depend on x. The force constants, K-t and K-o, were calculated and plotted against cobalt concentration x. Compositional dependence of the force constants is explained in terms of cation-oxygen bond distances and redistribution of cations.