Structural and size dependence magnetic properties of Mn-doped NiO nanoparticles prepared by wet chemical method

Ni_1−xMn_xO (x = 0.0–0.10) nanoparticles [NPs] were successfully prepared by wet chemical precipitation method at room temperature using polyethylene glycol as a capping agent. The structural, optical, microstructure, and magnetic properties of the prepared NPs were determined by XRD, FTIR, UV.PL SEM, TEM, EDS, and VSM analysis. XRD analysis confirmed the distorting of Mn²⁺ ions in the NiO lattice with FCC structure. The average crystalline size of undoped and Mn²⁺ NiO was found to decrease from 39 to 21 nm. Microstructure result shows that the prepared nanoparticles are polycrystalline in nature and the shape of the particles was hexagonal. Optical analysis shows the increase in bandgap from 3.81 to 4.27 eV by strong quantum confinement effect with blue shift in the UV absorption spectra range of 325–290 nm. EDS analysis confirmed that the samples are composed of Ni, Mn, and O without other impurities. FTIR spectra confirmed the formation of Ni–Mn–O stretching frequency. The VSM result suggests that the highest coercivity of about 620 Oe and Mn–Mn super-exchange interaction is responsible for the room-temperature ferromagnetism.