Akademik Veri Yönetim Sistemi
IEEE TRANSACTIONS ON MAGNETICS, cilt.46, sa.6, ss.1809-1812, 2010 (SCI-Expanded)
Both ZnO and Zn0.99Co0.01O semiconductors were synthesized through solid state reaction via mechanical milling and thermal treatment. Initially the wurtzite ZnO structures of the synthesized particles were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Since these techniques were unable to identify both contamination atoms and Co distribution, energy dispersive X-ray spectrometry (EDS) was used. EDS showed a successful doping of Co atoms with the atomic ratio of 0.9 +/-0.1%, and also showed a contamination of tungsten (W) atoms, in the atomic ratio of 1.6 +/- 0.2% for Zn0.99Co0.01O, and 1.3 +/- 0.2% for ZnO. Substitutions of Co+2 ions with Zn+2 host atoms in the ZnO lattice were exposed through X-ray photo spectroscopy (XPS) data of Co 2p electronic energy levels. UV-vis absorption spectroscopy (UV-vis) was also used to prove Co substitutions in the ZnO lattice. This was revealed by a decrease in band gap from 3.25 +/- 0.01 eV to 3.03 +/- 0.01 eV, and the existence of newly permitted transitions between intra ionic levels. The ferromagnetic effect of Co doping in ZnO lattice was revealed by the coercivity of similar to 154 +/- 50 Oe and positive Curie-Weiss temperature, 79 +/- 1 K. Beside ferromagnetic interactions, the calculated effective Bohr Magnetron (mu(eff)), 0.32 +/- 0.01 mu B, suggested anti-ferromagnetic interactions due to be less than the theoretical spin based magnetic moment of Co2+ ions, 3.0 mu B.