Structural, optical and magnetic properties of Zn1−xCuxFe2O4 nanoparticles prepared by microwave combustion method

Nano-sized copper doped zinc ferrite powders, Zn1−xCuxFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized by microwave combustion method. The structural, morphological and magnetic properties of the products were determined and characterized in detail by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). X-ray analysis showed that all compositions crystallize with a cubic spinel-type structure. The lattice parameter decreased from 8.443 to 8.413 Å with increasing Cu content. The average crystallite size was found in the range of 41.20–45.84 nm. Magnetic measurements revealed that for lower Cu concentration (x ⩽ 0.2), the system shows a superparamagnetic behavior whereas for higher concentration (x ⩾ 0.2), it becomes ferromagnetic. It has been explained in terms of random distribution of Zn2+ and Fe3+ ions at tetrahedral [A] and octahedral [B] sites. The saturation magnetization (Ms) varies considerably with Cu content to reach a maximum value for Cu0.5Zn0.5Fe2O4 composition, i.e. 58.58 emu/g. The high saturation magnetization of these samples suggests that this method is suitable for preparing high quality nanoparticles for magnetic applications. The broadband visible emission is observed in the entire photoluminescence (PL) spectrum and the estimated energy band gap is about 2.1 eV. The composition with x = 0.5 showed the highest intensity and was explained on the basis of disordered cluster model.