Structural characterization of CO doped ZnO nanocrystals by X-ray absorption spectroscopy

Complex and multinary oxides provide a wide range of functional materials especially when nanostructured. Nanocrystalline Zn1-xCoxO (x=0-0.50) particles are produced by chemical vapor synthesis (CVS) using laser flash evaporation as a novel precursor delivery method. The crystal and local structure of the samples is studied using X-ray diffraction and X-ray absorption spectroscopy. A single wurtzite phase is observed in samples with Cobalt contents as high as x = 0.25. X-ray absorption spectra show that the Co2+ ions are incorporated into the ZnO wurtzite lattice substituting Zn2+ ions for Cobalt contents between x=0.001 and x = 0.20. Only small lattice deformations are observed in these solid solutions. In order to investigate the local structure around Co and Zn and their distribution in the Zn1-xCoxO nanoparticles Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) spectra are analyzed in detail. These results are compared with XRD measurements to reveal the correlation between doping concentrations and non-isotropic strain in the nano particles. In addition, theorical calculation is done for Co doped ZnO nanomaterials by using FEFF8 code.