High-resolution electron microscopy of metal/metal and metal/metal-oxide interfaces in the Ag/Ni and Au/Ni systems

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Abstract
The atomic structures of heterophase interfaces with large misfits (>14% in Ag/Ni and Au/Ni) and with small misfits (∼2% in Ag/NiO and Au/NiO) have been studied by high-resolution electron microscopy (HREM). It is found that all interfaces are strongly faceted on (111) planes. This indicates that (111) interfaces have the lowest interfacial energy in both metal/metal and metal/metal-oxide systems. For the metal interfaces, this also agrees with determinations of interfacial energies by lattice statics calculations. The large misfit of Ag/Ni and Au/Ni interfaces is accommodated by misfit dislocations. Observations of misfit localization by HREM are in good agreement with images derived from computer simulation, based on relaxed structures, obtained in embedded atom calculations. All misfit dislocations at the Ag/Ni and Au/Ni interfaces lie exactly in the plane of the interfaces, while the dislocations at Ag/NiO and Au/NiO interfaces reside at a stand-off distance, 3 to 4 (111)Ag or (111)Au interplanar spacings from the interfaces.