Magnetic properties of Zn1−xCoxO bulks prepared by hot pressing

Zn1−xCoxO-diluted magnetic semiconductor bulks have been prepared by hot pressing. Mixed powders of pure ZnO and CoO were compacted under pressure of 10 MPa at the temperature of 1073 K. Then, the samples were annealed in vacuum at the temperature range from 673 K to 873 K for 10 h. The crystal structure and magnetic properties of Zn1−xCoxO bulks have been investigated by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). X-ray photoelectron spectroscopy (XPS) and was used to study chemical valence of zinc and cobalt in the samples. The results showed that Zn1−xCoxO samples had c-axis-oriented wurtzite symmetry neither cobalt nor cobalt oxide phase was found in the samples if x was less than 0.15. Zn and Co were existed in Zn0.9Fe0.1O sample in Zn2+ and Co2+ states. The results of VSM experiment proved the room temperature ferromagnetic properties (RTFP) of Co-doped ZnO samples. The saturation magnetization and the coercivity of Zn0.9Co0.1O sample, observed in the M–H curve, were about 0.22 emu/g and 300 Oe, respectively.