First-principles study on the elastic anisotropy of Au-Sn intermetallic compounds

Independent elastic constants of single-crystal Au₅Sn and AuSn were determined through first-principles calculations to characterize their elastic anisotropy. The ideal elastic moduli and Poissonpsilas ratio of Au₅Sn were determined using the Voigt-Reuss-Hill method and were very close to the range of experimental results; but the ideal Youngpsilas modulus of AuSn was much smaller than the experimentally obtained values. This unusual discrepancy in the Youngpsilas modulus values of AuSn is probably attributed to its extraordinarily high anisotropy in Youngpsilas modulus with a 95 GPa difference between its maximum and minimum values. Au₅Sn exhibits relatively low anisotropy in Youngpsilas modulus with the maximum-minimum difference of 38 GPa.