Room-Temperature Ferromagnetism in Mn-Doped ZnO Nanoparticles Synthesized by the Sol-Gel Method

In the current work,pure ZnO and Mn-doped ZnO nanoparticles weresynthesized by the sol-gel autocombustion method. Structuralanalysis and phase determination were done by X-ray diffraction, anda hexagonal wurtzite structure was exhibited with disparate microstructuresfor all samples. Mn2+ ions were well composed, as evidencedby the fluctuation of lattice parameters, dislocation density, andlattice strain. Crystallite size decreases from 38.42 to 27.54 nmby increasing the doping concentration. Field emission scanning electronmicroscopy results shows the combination of evenly distributed spherical-likeand hexagon-like structures. Fourier transform infrared spectra revealedthat when Mn content increased, the absorption bands red-shifted.The drop in the energy band gap from 3.25 eV for ZnO to 2.99 eV forZn(0.96)Mn(0.04)O was predicted by ultraviolet-visibleabsorption spectra. This red shift in the energy band gap can be explainedby the sp-d exchange interaction between the band electronsof ZnO and localized d electrons of Mn. A study of magnetic propertiesrevealed the change of the diamagnetic attribute for pure ZnO to theroom-temperature ferromagnetic attribute of doped samples. In thecurrent study, room-temperature ferromagnetism was achieved for Mn-dopedZnO nanoparticles, which can serve as a desirable option for practicalapplications in the future.