Valence states of titanium atoms in non-stoichiometric carbides: X-ray emission spectra and cluster calculations

Abstract

The K_{beta 5} and L_alpha X-ray emission bands of titanium carbide and the compound TiC_0.65 are considered. Splittings of the bands have been found for the non-stoichiometric compound. Based upon the correspondence between experimental spectra and the results obtained in MO-LCAO calculations on both defect clusters and complete clusters, the authors conclude that the deviation from stoichiometry causes a change of valency for the transition metal. That valency change leads to an increase in the electronic density of states near the Fermi energy mainly associated with metal d character. No evidence for significant electron localisation at vacancy sites has been found either in theoretical or experimental results.