Abstract
In this study, we report high cobalt concentration doped ZnO (Co content from 0 up to 16%) prepared by both solid reaction and chemical precipitation methods. The X-ray powder diffraction patterns show that most diffraction peaks slightly shift to lower degrees with increasing cobalt content. As a result, the crystal lattice constant increases with the Co content. Our results of Raman scattering spectra show that the A1, E1 and E2 vibration phonon modes of Co-ZnO shift to lower frequencies with increasing cobalt concentration. The intensity of the A1 mode increase with the Co content. The electric polarization of Co-O is stronger than that of Zn-O. The results of SQUID magnetometer show that the Co-ZnO samples fabricated by the chemical precipitation method exhibit paramagnetic property with magnetic susceptibility up to 0.1296 emu/g•T at 16% Co content under room temperature. The Co-ZnO samples prepared by chemical precipitation method have stronger paramagnetic property than samples by solid reaction. The result of X-ray absorption near edge structure shows the Co atoms in Co-ZnO structure are at +2 oxidation state.