UNDERSTANDING ADHESION BETWEEN METAL AND OXIDE

The nature of the adhesion of oxide to metal is a problem which we are only just beginning to understand from a fundamental point of view. What governs the choice of atomic sites where oxide and metal make contact? What is the chemical nature of the interatomic bonding and how strong is it? It has very recently become possible to solve the Schrodinger equation with sufficient accuracy to answer these questions for a simple system. We illustrate this with the niobium-sapphire interaction, for which the calculations provide an explanation of the structure observed in high resolution transmission electron microscopy. Some of the results of detailed quantum mechanical calculations can be interpreted with simple electrostatic concepts such as ionic bonding and the image interaction.