Effect of Annealing Temperature on Structural and Magnetic Properties of Zn0.94Co0.05Cu0.01O

The doped ZnO system Zn0.94Co0.05Cu0.01O (ZCCO) was prepared as a nano-polycrystalline by a sim- ple sol-gel process, then air annealed at different tempera- tures. Applying X-ray diffraction (XRD) and the Rietveld method, structural analysis showed that Co and Cu replace Zn substitutionally yielding ZCCO single phase. The re- fined u-fractional coordinate of Zn increases monotonically by an annealing temperature from 0.3546 at 500 °C reach- ing 0.3722 at 800 °C, very near from the ideal value 0.375. The Zn tetrahedrons become more symmetric and the dis- tortion is gradually relieved by annealing up to 800 °C. An- nealing at 900 °C introduces tetrahedron distortion in an opposite way. The zero field cooled (ZFC) and field cooled (FC) magnetization versus the temperature at different ap- plied fields and the magnetization versus the applied field at different temperatures were carried out. The system ex- hibits a ferromagnetic behavior at room temperature. As the annealing temperature increases from 550 to 900 °C, the saturation magnetization at 300 K increases from 0.0507 to 0.1088 emu/g.