Solvent dependent shape and magnetic properties of doped ZnO nanostructures

This study reports on a new solution phase synthesis leading to cobalt and manganese doped ZnO which have been theoretically predicted ferromagnetic at room temperature. The solvothermal synthesis involving the reaction of zinc and cobalt acetate or manganese oleate with benzyl alcohol leads to pure inorganic nanoparticles that are diluted magnetic semiconductors. The addition of an inert solvent, that is used in order to control the amount of benzyl alcohol, drastically influences the particles morphology and strongly affects the magnetic behaviors. Cobalt doped particles are paramagnetic or ferromagnetic depending on the synthesis conditions. In order to exclude the formation of secondary phases and/or metal clusters and to understand the role of the solvent on the magnetic properties, the local structure of Co2+ and Mn2+ in the wurtzite ZnO matrix were characterized by XRD, UV-visible diffuse reflectance and electron paramagnetic resonance.