X-Ray Diffraction and X-Ray Spectroscopy Studies of Cobalt-Doped Anatase TiO2:Co Nanopowders

Cobalt-doped anatase Ti0.97Co0.03O2 nanopowders with a particle size of about 100 °A were produced by a microwave-hydrothermal method. The obtained samples were characterized by means of X-ray diffraction, X-ray absorption (Ti L2,3, Co L2,3, and Co K), and 1s3p resonant inelastic X-ray scattering spectroscopies. Co2+ ions tetrahedrally coordinated by oxygen ions in nanoparticles were found to be located on the surface of agglomerates. Titanium ions were found to be in a tetravalent state (Ti4+). All the samples before the thermal treatment contain an amorphous phase of titanium dioxide on the surface. After annealing in vacuum or hydrogen anatase structure of Ti0.97Co0.03O2 remains and the amorphous phase disappears. Annealing the samples in vacuum or hydrogen leads to clustering metal cobalt at the particles from the bulk of agglomerates.