Electronic Structure of Alpha Brass

Abstract

We have investigated the band structure of alpha brass ($\ensuremath{\alpha}\ensuremath{-}\mathrm{C}\mathrm{u}\mathrm{Z}\mathrm{n}$) as a function of its composition, over a range of 5 to 30% Zn, by steps of 5%. The Kohn-Rostoker method was used in combination with a spherical-average model potential. The conduction bands were determined at high symmetry points of the Brillouin zone. It was assumed that the $\mathrm{Cu}d$ bands are unchanged by alloying. It was found that the conduction bands are displaced to lower energies, the ${L}_{{2}^{\ensuremath{'}}}\ensuremath{-}{L}_{1}$ gap across the {111} faces of the zone is reduced by 1.3 eV at 30% Zn, and the Fermi surface approaches the {200} faces of the zone. Our results are used to interpret the measured optical properties (Rayne and Biondi, Green), and to give a semiquantitative discussion of the theory of alloying and alpha-phase stability.