Effect of high spin Mn2+ /Mn3+ ions on microstructural, optical, magnetic and electrical properties of hydrothermally prepared Ni–Mg nanoferrites

Abstract

A nanoferrite series of composition [Formula: see text] with [Formula: see text] and 0.4 has been prepared by a hydrothermal method. X-ray diffraction (XRD) confirmed the formation of cubic spinel structure. The average crystallite size is found to be in the range of 28–48 nm. The lattice parameter is found to increase linearly with an increase in [Formula: see text] content. Field Emission Scanning Electron Microscopy micrographs indicate that the samples have almost uniform sized crystallites with uniform grain growth. Fourier Transform Infrared (FTIR) Spectroscopy studies showed two absorption bands close to 603 and [Formula: see text] for the tetrahedral and octahedral sites respectively. Saturation magnetization attained a maximum value of 34.15 emu/g at [Formula: see text] and then decreases for higher concentrations of [Formula: see text] ions. Activation energy for compositions [Formula: see text] and [Formula: see text] are found to be 0.371 eV and 0.471 eV, respectively. For composition [Formula: see text], maximum value of observed density, minimum porosity, maximum value of saturation magnetization, maximum initial permeability and minimum value of coercivity is obtained. DC resistivity is found to be of the order of [Formula: see text]. The obtained results have been explained based on possible mechanisms, models and theories.