MISFIT DISLOCATIONS AT METAL-CERAMIC INTERFACES

A metal-ceramic interface is produced by depositing Al on a {100} MgO substrate in an MBE system. The interface is studied with high resolut ion electron microscopy. Results of some image simulations are shown, raising the question if effects of ionicity and charging should be tak en into account. From the atomistic modelling concentrating on the eff ects of mismatch and bonding strength at metal-ceramic interfaces it i s shown that the misfit and the strength of the binding between metal and ceramic can be controlled. The model is applied to a simple case, an interface with mismatch in one direction, and calculated energies a nd atomic structures for various mismatches and bonding strengths. The structure of the misfit dislocations is shown to depend on mismatch a nd bonding strength. A clear trend from delocalised structures to loca lised ones that behave like bulk-like dislocations can be seen for dec reasing misfit at constant interaction, and increasing interaction at constant misfit.