Structural, Magnetic, and Electrical Properties of Ni0.65Zn0.35-x Cu x Fe2 O4 Nanoferrite System

Copper-substituted Ni-Zn nanoferrite system having the composition of Ni0.65Zn0.35-x Cu (x) Fe2O4 (x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25) has been prepared by autocombustion method. Structural and magnetic characterizations were done on the as-prepared powders while the dc electrical conductivity measurements were studied on pellets sintered at 900 C-a similar to. X-ray diffraction measurements of all the samples showed a single spinel phase. The lattice parameter has been found to decrease with increasing Cu, and this variation in the spinel unit cell is ascribed to the difference in the ionic radius of Cu2+ and Zn2+ ions. The average crystallite size was determined using the Scherrer equation. The dc electrical resistivity of nanocrystalline starting composition Ni0.65Zn0.35Fe2O4 was few orders of magnitude higher than the bulk Ni0.65Zn0.35Fe2O4 prepared by conventional ceramic method. However, Curie's temperatures and dielectric constant were decreased with increasing copper concentration. The observed variation in dc electrical resistivity and activation energy for conduction with Cu2+ substitution is attributed to changes in the microstructure, structural defects, and hopping mechanism.