Sol–gel synthesis and room temperature ferromagnetism in Mn doped ZnO nanocrystals

Abstract

We report the synthesis of Zn1−x Mn x O nanoparticles prepared by a sol–gel processing technique for x ranging from 0 to 0.05. The structural, morphological and magnetic properties of the nanoparticles were investigated by XRD, transmission electron microscopy and superconducting quantum interference device. The structural properties showed that the obtained nanoparticles are in wurtzite phase structure with the presence of ZnMnO3 secondary phase at higher concentration. The crystallite size decreases with increasing Mn concentration and is in the range of 35–17 nm. All the samples are ferromagnetic with clear hysteresis loop at room temperature but with low values for the saturation. It was found that increasing Mn concentration is not helping the long range ferromagnetic order, which might be due to the antiferromagnetic exchanges. This ferromagnetism order is due mainly to the defects and to the substituting of Mn in the ZnO host rather than from the secondary phases of Mn.