Effect of Cu2+ doping on structural, morphological, optical and magnetic properties of MnFe2O4 particles/sheets/flakes-like nanostructures

Cu2+ doped MnFe2O4 (Mn1-xCuxFe2O4; x=0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) nanomaterials with different morphologies such as nanoparticles, nanosheets and nanoflakes have been synthesized by the urea assisted one-pot microwave combustion method. X-ray diffraction (XRD) studies showed that the samples have pure cubic spinel phase, and the average crystallite size is found to be in the range of 31-44 nm. The lattice parameter is decreased from 8.477 to 8.455 angstrom with increasing Cu2+ content, which is determined by Rietveld analysis. The morphology of the samples were recorded by high resolution scanning electron microscope (HR-SEM) analysis, and was found to change considerably from nanoparticles to nanosheets and then to nanoflakes with increasing Cu2+. The energy dispersive X-ray (EDX) results showed that the composition of the elements were relevant as expected from the synthesis. The optical properties of the as-prepared nanostructures were also investigated by UV visible diffuse reflectance spectra (DRS) and photoluminescence (PL) spectra. The DRS study showed the energy band gap (E-g) of the pure MnFe2O4 is 1.76 eV, and with increase in Cu2+ ion, it increases from 1.96 to 2.53 eV. The magnetic properties were investigated at room temperature by using the vibrating sample magnetometer (VSM) and the hysteresis loops confirmed the ferromagnetic behavior for all the samples with saturation magnetization (M-s) values in the range of 49.42-66.89 emu/g. The decrease of M-s with Cu-doping may be due to the difference in the magnetic moment of Cu2+ and Fe3+ ions. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.