ELECTRONIC-STRUCTURE OF AU-TI INTERMETALLICS

Core-level binding energy shifts and valence-band behavior for Au-Ti intermetallic compounds Au2Ti and AuTi3 have been studied with x-ray photoelectron spectroscopy. It is found that the observed Au 4f binding energy shift of the intermetallic compounds, relative to the pure metal, is not consistent with simple electronegativity predictions. The results are interpreted in terms of a charge compensation model, i.e., that there is an increase in the number of sp-like conduction electrons accompanied by a decrease in the d-electron count at the Au site resulting in a small net charge flow onto Au from Ti. Au L2,3 x-ray absorption near edge structure measurements provide independent evidence for d-charge depletion at the gold site. A significant valence-band narrowing as well as a reduction in the spin-orbit splitting of the Au portion of the d band is also observed upon dilution. The implications of these results are discussed.