Electronic structure of omega phase of titanium and zirconium

Abstract

The electronic structures of alpha (HCP, atmospheric pressure) and omega (simple hexagonal, high-pressure) phases of Ti and Zr have been calculated using the nonrelativistic APW method. The discriminating features of the bandstructure of the omega phase as compared to the alpha -phase are the reduced s-d spacing, a broad d band without sharp resonances and the location of the Fermi level. In the case of the alpha phase the Fermi level lies in a valley, while in the case of the omega phase it lies near the centre of a broad maximum. Comparison of the theoretical electronic structures is also made with empirical bonding models of the omega phase. AnESCA (XPS) study of the alpha and omega samples shows the principal features of the d band and location of the Fermi level in agreement with the theoretical predictions, though the XPS patterns are inescapably affected by surface oxygen contamination.