Phase diagram for the Ni/Al$_{2}$O$_{3}$ interface and relationships to adhesion

First-principles$^{ }$calculations conducted over a broad range of atomic configurations have$^{ }$been used to determine the phase diagram and work of$^{ }$separation for Ni/Al$_{2}$O$_{3}$ interfaces[1]. Seven interfacial phases have been identified.$^{ }$The results reveal that the strongest (O-rich) phases derive their$^{ }$strength from ionic Ni-O bonds across the interface, reminiscent of$^{ }$NiO. The Al-rich phases are also strong, exhibiting a mix$^{ }$of Ni$_{3}$Al-like and Al$_{2}$O$_{3}$-like interfacial bonds. The stoichiometric interfaces are$^{ }$the weakest since they are formed from the ground-state Al$_{2}$O$_{3}$(0001)$^{ }$surface. [1] X.-G. Wang, J. Smith, A. G. Evans, Phys. Rev. B 74, 081403(2006).