HIGH-RESOLUTION ELECTRON-MICROSCOPY OF CU/MGO AND PD/MGO INTERFACES

Cu/(1 $($) over bar$$ 11)MgO and Pd/(1 $($) over bar$$ 11)MgO interfaces with a cube-on-cube relation are produced by the internal oxidation technique. High-resolution transmission electron microscopy has been applied to study the interface structures of Cu/(1 $($) over bar$$ 11)MgO and Pd/(1 $($) over bar$$ 11)MgO. In contrast to a previous work in which cases the core structures of interfacial dislocations in Cu/(1 $($) over bar$$ 11)MgO and Pd/(1 $($) over bar$$ 11)MgO interfaces could not be directly observed from the high-resolution images, we have observed localized interfacial dislocations in both Cu/(1 $($) over bar$$ 11)MgO and Pd/(1 $($) over bar$$ 11)MgO interfaces from high-resolution images. Each interfacial dislocation in the Cu/(1 $($) over bar$$ 11)MgO and Pd/(1 $($) over bar$$ 11)MgO interfaces actually contributes to sets of zig-zag dislocations in a hexagonal network. Viewing along [110], the overlapped distances of the zig-zag interfacial dislocations in the network are similar to 0.5 and 1 nm for the Cu/MgO and Pd/MgO interfaces, respectively, which is comparable with the observed 'localized width' of interfacial dislocations from high-resolution images. The atomic structures of these two metal/oxide interfaces are determined from through-focal series of high-resolution images. The terminating lattice plane in the interface is the oxygen lattice plane for both Cu/(1 $($) over bar$$ 11)MgO and Pd/(1 $($) over bar$$ 11)MgO interfaces which are composed of distorted structural units of Cu2O and PdO, respectively. Junction dislocations resembling those in grain boundary facets, related to the difference of the rigid body translations, are observed between two energeticallty equivalent {1 $($) over bar$$ 11} facets in the Cu/MgO and Pd/MgO interfaces. The Burgers vector of the junction dislocation is 1/6[112] and a stacking fault in the soft metal matrix is found accompanying this junction dislocation.