Incorporation of chromium into TiO2 nanopowders

• Nanopowders of TiO2:Cr with different amount of Cr dopant were obtained by flame spray synthesis, FSS.
• Increase in the optical absorption and a shift of the absorption edge were observed upon Cr doping.
• HERFD-XANES measurements indicated that the average valence state of titanium ions was preserved.
• Increasing magnetic susceptibility of a paramagnetic character was observed upon Cr doping.

The paper reports on the results of a study of optical, electronic and magnetic properties of TiO2 nanopowders doped with Cr ions. Diffused reflectance spectra reveal an increase in the optical absorption and a shift of the absorption edge towards lower energies upon Cr doping. Direct information on the Ti electronic state and the symmetry of its nearest environment is obtained from XANES Ti K-edge spectra. Magnetic behaviour is probed by means of the temperature dependence of DC magnetic susceptibility. Increasing magnetic susceptibility of a paramagnetic character is observed upon increasing chromium doping. The Curie constant of TiO2:10 at.% Cr sample (0.12 emu K/mol Oe) is lower than that expected for Cr3+ (0.1875  emu K/mol Oe) possibly due to the appearance of Cr4+ or the presence of the orbital contribution to the magnetic moment.

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