Microstructural and magnetic properties of Ni 1-x Cu x Fe 2 O 4 (x = 0.05, 0.1 and 0.15) nano-crystalline ferrites

An attempt was made to synthesize Ni1-xCuxFe2O4 (x = 0.05, 0.1 and 0.15) nano-crystalline ferrites by sol–gel auto-combustion method and study their micro-structural, magnetic and dielectric properties. From the X-ray diffraction patterns, the lattice constants, average crystallite size, grain size of these compounds were calculated and compared to those of the nickel ferrite. The cation distribution obtained from X-ray diffraction shows that the copper occupies only tetrahedral sites in spinel lattice. The lattice constant of the ferrites under consideration increases with increasing the copper content. The structural parameters such as bond lengths, tetrahedral and octahedral and octahedral edges were varied by copper substitutions. The microstructural study was carried out by using SEM technique. It implies that the average grain size increases with increasing the copper concentration. Similar tendency was observed for the initial permeability (μi). It turns out from the electron spin resonance investigation that the g-factor decreased linearly with increasing magnetic fields as well as dopant concentrations.