Ferromagnetism of Ni-doped ZnO powders prepared by sol-gel method above room temperature

The magnetic and structural properties of 2% Ni-doped ZnO powers prepared by sol-gel method were studied. X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) of the sample do not show existence of any signal of second phase. The X-photoelectron spectroscopy (XPS) of the sample shows the chemical valence of Ni is + 2 and the real Ni concentration is 2.19% determined by X-ray fluorescence spectra (XRFS). The magnetic property performed with superconducting quantum interference device (SQUID) shows that the sample exhibits ferromagnetism above room temperature and the Curie temperature (T-C) is about 600 K.