A LOCK-IN MODEL FOR THE ATOMIC-STRUCTURE OF INTERPHASE BOUNDARIES BETWEEN METALS AND IONIC-CRYSTALS

The low energy interphase boundaries were determined at 550 degree C by means of the boundary energy-induced rotation of small spheres. The systems were chosen so that the effect of lattice mismatch, the effect of lattice structure, and chemical effects could be studied. The results obtained suggest that boundary models based on the coincidence concept are not applicable to interphase boundaries between noble metals and ionic crystals because the low energy boundaries observed were not of the coincidence type and existing coincidence orientation relationships did not result in low energy boundaries. A low-energy interphase boundary results if the close packed rows of atoms at the 'surface' of the metal crystal fit into the 'valleys' between close packed rows of atoms at the 'surface' of the ionic crystal.