Structure at abrupt copper-alumina interfaces: An ab initio study

The atomistic structure and the energetics of Cu(1 1 1)/(alpha)-Al2O3(0 0 0 1) interfaces for two experimentally observed interface orientation relationships were investigated from first-principles by means of the mixed-basis pseudopotential method. In the first orientation relationship, the [1 1 0] direction of Cu is parallel to the [1 0 1 0] direction of (alpha)Al2O3, and in the second the Cu is rotated with respect to the (alpha)-Al2O3 by 90° around the interface normal [0 0 0 1]. Numerous candidate systems were considered for each case, covering all high-symmetry interface configurations, and with either Al or O termination of the (alpha)-Al2O3(0 0 0 1) surfaces. For each of the most stable interfaces, full relaxations of the positions of all atoms were performed. It is found that despite the different atomistic structures of the two interface types, their interface stabilities, in terms of the work of separation, and their local atomistic structures are similar.