Bonding nature of metal/oxide incoherent interfaces by first-principles calculations

A bonding mechanism of large-mismatched metal/oxide heterointerfaces, classified as incoherent interfaces, is investigated by first-principles calculations. As a model system, incoherent Ni Zr O2 (111) interfaces are selected, and the interfacial bonding characters and their relevance to the interface strength are analyzed. It is found that the chemical bonds of the interfacial atomic pairs are strongly dependent on the atomic configurations in the interface structures, and show a site-dependent character from ionic through covalent/metallic bonding. Thus, even in the presence of a large misfit, stable interfaces can be formed by an effective chemical bonding transition along the interfaces. First-principles tensile tests show that such a bonding multiplicity strongly affects the atomic-scale fracture behavior and ideal mechanical strength of the interfaces.