Photoluminescence and Magnetism in Mn2+-Doped ZnO Nanostructures Grown Rapidly by the Microwave Hydrothermal Method

Zn1-xMnxO nanostructures were synthesized via the microwave-assisted hydrothermal method, which rapidly produces particles of controlled size and morphology. Samples were analyzed considering the effects of manganese ion concentration. XRD revealed that all samples had wurtzite-type structure with Mn2+ ions incorporated in the oxide lattice. UV-vis spectra showed absorption bands from the d-d transitions of Mn2+ ions. As the doping concentration increased, the value of the energy gap decreased, indicating intermediary energy levels within the band gap in the Mn-doped ZnO samples. All samples produced broadband photoluminescence (PL) emissions in the yellow-orange-red range. Additionally, the PL intensity decreased with Mn2+ ion incorporation into the ZnO lattice due to the creation of new recombination centers. Microscopy images showed that manganese in the ZnO matrix produced homogeneously distributed nanostructures. EPR results indicated two locations of Mn2+ ions in the ZnO lattice, lower concentrations in the core of the lattice and higher concentrations at the surface.