STRUCTURAL, OPTICAL AND MAGNETIC INVESTIGATIONS ON UNDOPED AND Mn-DOPED ZnO NANOPARTICLES

Undoped and Mn (1 and 3 at.%) doped ZnO nanoparticles were synthesized by a simple chemical co-precipitation method. Rietveld refinement of X-ray diffraction (XRD) data revealed that undoped and Mn doped ZnO nanoparticles crystallize in the monophasic wurtzite structure and monotonous expansion of the lattice constants with increasing Mn content, due to the effective Mn doping. TEM images of all the samples showed the monodispersive spherical particles with the size of similar to 7 nm. The quantum confinement of nanoparticles was tested from UV-Vis absorbance measurement and the particle sizes were calculated and compared with TEM and XRD. The chemical compositions were analyzed by energy dispersive spectroscopy (EDS). In order to investigate the origin of ferromagnetism, the electronic structures of the Zn, O, and Mn atoms were probed by X-ray photoelectron spectroscopy (XPS). XPS data revealed that most of the dopants (Mn) exists in +2 oxidation state for 3 at.% Mn doped ZnO sample. The magnetization curves of the Mn doped ZnO samples indicate the existence of roomtemperature ferromagnetic (RTFM) behavior. Here the observed RTFM in Mn doped ZnO can be attributed to the substitutional incorporation of Mn at Zn sites rather than due to the formation of any secondary phases.