Synthesis and characterization of ZnO:Co2+ nanoparticles

This work investigates cobalt doped ZnO nanoparticles prepared by using wet chemical methods. The nanoparticles have a typical size of 3-8 nm. The electronic structure as well as the optical and magnetic properties of Co2+ have been characterized. X-ray diffraction spectra of the powder show wurtzite ZnO with no secondary Co phases. In the energy range below the bandgap, the optical absorption spectra show the internal d-d transitions related to Co2+ incorporated on the Zn lattice site in ZnO. Low temperature photoluminescence measurements confirm these results. Based on the analysis of the g-valuesfor bulk ZnO:Co., electron paramagnetic resonance measurements coincide with the simulation of Co-doped ZnO powder. Thus far, no evidence for ferromagnetism has been obtained.