Structural, optical, morphological and magnetic properties of Cu0.25M0.75Fe2O4 (M=Mn, Mg, Ni and co) ferrites for optoelectronic applications

The nanostructured Cu0.25M0.75Fe2O4 (M = Mn, Mg, Ni, Co) ferrites were obtained by the sol-gel auto -com-bustion method and their structural, magnetic, morphological and optical properties were investigated. The characterization techniques like XRD, UV-Vis, VSM, SEM, EDX and FTIR were employed to explore the obtained spinel ferrites. The XRD analysis revealed that all the compounds were single-phased spinels, showing no sec-ondary phase peaks in the diffraction patterns. According to Vegard's law, the average lattice constant of ferrites calculated from XRD data ranged from 8.413 angstrom to 8.131 angstrom, whereas crystallite sizes ranged from 18.978 nm to 42.351 nm on account of the increased annealing temperatures. The SEM study revealed that the ferrites powder morphology consisted of a merger of spherical and octahedral-shaped grains. The EDX study confirmed the stoichiometric ratios of constituent contents of Cu0.25M0.75Fe2O4 (M = Mn, Mg, Ni, Co) ferrites. In the M-doped Cu0.25M0.75Fe2O4 (M = Mn, Mg, Ni, Co) ferrites, the Jahn-Teller effect was also raised, as explored by the FTIR study of the ferrites. The UV-Vis spectroscopy analysis showed that the ferrites exhibited a direct band gap ranging from 2.961 eV to 2.189 eV. The M -H hysteresis curves of the ferrites recorded by VSM at room temperature revealed that the saturation magnetization, retentivity, coercivity, squareness, magnetic anisotropy and the magnetic moment severely depended on the substituent M content of ferrites. The investigation of magnetic properties also indicated that the successive substitutions of M in Cu0.25M0.75Fe2O4 (M = Mn, Mg, Ni, Co) ferrites changed its behavior from ferrimagnetic to ferromagnetic, even though the Jahn-Teller effect significantly interrupted such a transition. This feature enabled a practical application of Cu0.25M0.75Fe2O4 (M = Mn, Mg, Ni, Co) ferrites in optoelectronic devices.