Atomistic Thermodynamic Simulation of Ag/Al_2O_3 Interfaces under O_2 Pressure

Ag/α-Al2O3 interfaces of O-, Al-, and Al2-termination were calculated by an ab initio method. The dependence of the stability of the interfaces on O2 partial pressure at 1300K was built through the so-called ab initio thermodynamics. Two approaches were performed to bridge the gap between ab initio calculation and real experimental condition, corresponding to analyzing data based on either Al chemical potential or O chemical potential respectively. The approaches caused a 4 order of magnitude difference of the O2 partial pressure at which interfacial structure transits from Al-termination to O-termination. Further analysis shows that the real transitional point should fall in between the results from the two approaches, and the result based directly on Al chemical potential is closer to the real point. Our results show the same trend of interfacial stability in comparision with the reported wetting experiments, and the predicted transitional points for different terminations are also close to experimental one.