Cation distribution, structural and electric studies on cadmium substituted nickel-zinc ferrite

The structural and electric properties of Ni0.65-xZn0.35CdxFe2O4 (0 <= x <= 0.2) prepared by standard ceramic technique, have been studied. For all x values, X-ray powder diffraction was performed and the lattice constants and oxygen parameters were drawn from experimental data. Based on these values, other structural parameters like cation-cation, cation-anion distances, bond angles and hopping length were calculated, and the cation distribution was proposed by comparing observed and calculated X-ray diffraction intensities. It was found that substitution of larger cadmium into the lattice resulted in a significant change in the structural parameters. The microstructure of the samples was investigated using SEM micrographs and we found a substantial grain growth (observed mainly for x = 0.16 and 0.20) due to cadmium diffusion. Carrier mobilities for all samples were drawn from our DC electrical conductivity results and the variation of mobility with composition and temperature is presented. Dielectric measurements were performed at a standard frequency 1 kHz and the dielectric constant and loss factor were found to decrease first from x = 0 to x = 0.12 with the abrupt increase above this composition.