Structural, Optic, and Magnetic Investigation of the Synthesized ZnO and Zn $_{0.99}$Co $_{0.01}$O Semiconductors via Solid

Both ZnO and Zn_0.99Co_0.01O 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 Zn_0.99Co_0.01O, 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 d-d* levels. The ferromagnetic effect of Co doping in ZnO lattice was revealed by the coercivity of ~154?50 Oe and positive Curie-Weiss temperature, 79 ? 1 K. Beside ferromagnetic interactions, the calculated effective Bohr Magnetron (?_eff), 0.32?0.01 ?_B, suggested anti-ferromagnetic interactions due to be less than the theoretical spin based magnetic moment of Co²⁺ ions, 3.0 ?_B.