First principles study of Au-Sn intermetallic compounds

Abstract

A first-principles plane-wave pseudopotential method based on the density functional theory is used to investigate the energies, electronic structures, and elastic properties of intermetallic compounds of Au-Sn system. The enthalpies of formation, the cohesive energies, and elastic constants of these compounds are estimated from the electronic structure calculations, and their structural stabilities are also analyzed. The results show that the Au5Sn compound is unstable with respect to other compounds, and the bonding effects of AuSn2 and AuSn4 are stronger than those of AuSn and Au5Sn, for there are the strong hybridizations between Au and Sn atoms in AuSn2 and AuSn4 compounds. The main bonding effect of AuSn is Sn–Sn bonding interaction, and due to the Au content being maximal in Au5Sn the bonding of p electrons in Sn conduction band is suppressed by the covalent bonding of Au–Au.