Effect of atmosphere on the magnetic properties of the Co-doped ZnO magnetic semiconductors

Zn1−xCoxO nanoparticles were synthesized by rheological phase reaction-precursor method in air and Ar, respectively. No secondary phase was observed with the sensitivity of XRD measurement. X-ray photoelectron spectroscopy and absorption spectra results indicated that Co2+ successfully incorporated into the wurtzite lattice at the Zn2+ sites. Raman spectra of Zn1−xCoxO obtained at air showed an additional broad vibrational mode, which can be attributed to disordered ZnOCo local vibrations; the mode of the samples obtained at Ar was not appeared. Magnetization measurements reveal ferromagnetism is only found in samples prepared in Ar revealing a close correlation between the defects and magnetic properties.