RELATIONSHIP OF CRYSTAL-STRUCTURES TO INTERIONIC INTERACTIONS IN MONOVALENT, DIVALENT, TRIVALENT AND TERVALENT METAL-OXIDES

The ability of an extended ionic interaction model to account for the observed crystal structures of a very wide range of binary oxides is a ssessed. The model includes the many-body effects which result from io nic polarization and their changes in effective size and shape of ions in different coordination environments. Starting from potentials whic h have been fully obtained for certain substances on the basis of elec tronic structure calculations, systematic modifications in the values of key parameters (such as ionic radii) are made, so as to derive pote ntials for other substances on the basis of an assumed transferability of an ionic interaction model. Comparison of the predicted structures with observation enables the identification of the key parameters whi ch control the evolution of structure type and the physical nature of the interactions responsible for the adoption of 'covalent' structures by some materials.