Local Structure Investigation of Cobalt and Manganese Doped ZnO Nanocrystals and Its Correlation with Magnetic Properties

Abstract

Co and Mn doped ZnO nanocrystals have been synthesized by two different routes, viz., a wet chemical method and a microwave-assisted nonaqueous method and it has been found that the samples prepared by the former method are ferromagnetic while those prepared through the later route are paramagnetic. Systematic investigation of these doped ZnO nanocrystals has been carried out by extended X-ray absorption fine structure technique to determine the changes in the local structure at the Zn and dopant sites. Co doped samples prepared by either of the techniques show almost similar behavior, with Co substituting Zn up to a 10% doping concentration, beyond which there is a signature of Co clustering. However, in the case of Mn doped samples, Mn clustering commences at lower values of doping (∼7%) for samples prepared by microwave-assisted method, while for nanocrystals prepared by the wet chemical method, Mn–K edge X-ray absorption near edge spectroscopy measurement reveals the presence of a Mn2O3 phase at lower...