Spectroscopic and structural studies of isochronally annealed cobalt oxide nanoparticles

• The XANES, XPS and SXRD techniques are used to study isochronally annealed cobalt oxide nanoparticles, to get complementary information.
• Quantitative estimation of phase composition using LCF based on XANES shows good agreement with Rietveld refinement based on SXRD.
• XPS data are also in agreement with SXRD and XANES results. Increase of Co3O4 concentration and reduction of adsorbed hydroxyl group on annealing has been observed.
• Crystal field splitting is found to be larger in nanoparticles as compared to that in the bulk.

X-ray absorption near edge structure (XANES) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Synchrotron X-ray diffraction (SXRD) techniques are used to study as synthesized and isochronally annealed samples of cobalt oxide nanoparticles (NPs) grown using the wet chemical route. Quantitative phase composition determined using Linear Combination Fitting (LCF) on XANES data is found to be in reasonably good agreement with that obtained from Rietveld refinement on SXRD data. XPS data qualitatively indicate that Co3O4 concentration increases with increase in the annealing temperature, in confirmation with SXRD and XANES data. Larger shifts in the satellite peaks from the main peaks compared to these in bulk suggest larger crystal field splitting in nanoparticles as compared to the bulk.