Co0.6Zn0.4Cu0.2CdxFe1.8−xO4 (0.2 ⩽ x ⩽ 0.8) magnetic ferrite nano-particle: Synthesis, characterization and photo-catalytic degradation of methyl orange

Cd2+ ion substituted nano-crystalline cobalt–zinc ferrites having chemical formula Co0.6Zn0.4Cu0.2CdxFe1.8−xO4 (x = 0.2, 0.4, 0.6 and 0.8) have been prepared using sol–gel auto-combustion method. The X-ray diffraction analysis confirmed the crystalline structure and phase purity of all the prepared nano-ferrites. The lattice constant was found to vary linearly from 8.360 Å to 8.390 Å for cadmium ion concentration from 0.2 to 0.8 in accordance with Vegard’s law. Ionic radii of tetrahedral site (rA) and octahedral site (rB) was found to increase with increase in the cadmium ion concentration because of larger size of Cd2+ ion (0.97 Å) as compared to that of Fe3+ ion (0.67 Å). Vibrating sample magnetometer (VSM) results revealed that the saturation magnetization, coercivity and anisotropy constant decrease with increase in the cadmium concentration. The distribution of cations among A and B sites of the lattice was estimated by the magnetic moments which were calculated from the magnetic data. Moreover resistivity was found to be decrease with increase in the cadmium concentration. There was increase in drift mobility with increase in temperature because of the enhanced mobility of charge carriers due to thermal activation. Co0.6Zn0.4Cu0.2CdxFe1.8−xO4 showed good catalytic activity towards methyl orange and easily recovered by magnetic separation after the reaction. The photo-catalytic degradation was enhanced as the concentration of cadmium ion increased from 0.2 to 0.8 may be due to decrease in band gap with increase in Cd2+ ion concentration.