Structural and magnetic properties of Li-Cu mixed spinel ferrites

Li0.5−x/2CuxFe2.5−x/2O4 (where x=0.0-1.0) ferrites have been prepared by solid-state reaction. X-ray diffraction was used to study the structure of the above investigated ferrites at various sintering temperatures. Samples were sintered at 1000, 1100 and 1200 °C for 3 h in the atmosphere. For the sintering temperature of 1000 °C, Li0.5−x/2CuxFe2.5−x/2O4 undergoes cubic to tetragonal transformation for higher Cu content. However, for the sintering temperature of 1100 and 1200 °C, X-ray diffraction patterns are mainly characterized by fcc structure, though presence of tetragonal distortion was found by other temperature dependence of initial permeability curves. The lattice parameter, X-ray density and bulk density were calculated for different compositions. Curie temperature was measured from the temperature dependence of initial permeability curves. Curie temperatures of Li-Cu mixed ferrites were found to decrease with the increase in Cu2+ content due to the reduction of A-B interaction. As mentioned earlier, temperature dependence of initial permeability curves was characterized by tetragonal deformation for the samples containing higher at% of Cu. The complex initial permeability has been studied for different samples. The B-H loops were measured at constant frequency, f=1200 Hz, at room temperature (298 K). Coercivity and hysteresis loss were estimated for different Cu contents.