Effect of Au Doping on Elastic, Thermodynamic, and Electronic Properties of η-Cu6Sn5 Intermetallic

The effects of substitution of Au for Cu on the elastic, thermodynamic, and electronic properties of hexagonal eta-Cu6Sn5 intermetallic compound (IMC) are investigated by first-principles calculations. The results show that Au atoms preferentially occupy Cu4 or Cu3 site to form eta-Cu5Au1Sn5 or eta-Cu4Au2Sn5 IMC, respectively. Doping Au in eta-Cu6Sn5 IMC forms a more stable thermodynamic structure than pure phase. The ductility of eta-Cu6Sn5 IMC increases after substitution of Au for Cu. However, doping Au weakens the Young's modulus, shear modulus, hardness, and Debye temperature of eta-Cu6Sn5 IMC. The results for the charge density difference, total density of states, and partial density of states show that doping Au atoms can stabilize the structure of eta-Cu6Sn5 IMC.