Room Temperature Ferromagnetism in Ni Doped ZnO Powders

Zn1−x Ni x O (x=0.1%, 0.4%, 0.7%, 1.0%) powders were prepared using the sol-gel technique, and the structural, optical, and magnetic properties of the samples were investigated. X-ray diffraction measurements show that all samples have a wurtzite structure and that the c-axis lattice constant decreases as the Ni content increases. X-ray photoelectron spectroscopy studies reveal that the doped Ni ions are in divalent states in all samples. Optical absorption spectra show that the band energy of Zn1−x Ni x O powders decreases with increasing Ni concentration. Photoluminescence measurements of Zn1−x Ni x O show a broad peak at a wavelength centered at about 467 nm which indicates the presence of a fraction of defects in ZnO. The room temperature ferromagnetism observed in all samples is intrinsic in nature.