Point defects and diffusion at the Ni/Sapphire interface: a first principles perspective

Metal-Ceramic interfaces are ubiquitous in many technologies with applications in semiconductor devices, thermal barrier coating for turbine blades, catalysis and thin-films to name a few. Diffusion along metal-ceramic interfaces is a key factor in the performance of all these applications/devices. Experimentally, the difficulty in separating the effect of metal-ceramic diffusion from bulk diffusion makes it a challenging area of research. In the present work, we use ab initio calculations to characterize the interface system of Ni/Sapphire with respect to changing environmental conditions such as the partial pressure of Oxygen. We provide a complete analysis of various point defects that can happen at or near the interface and the probable diffusion paths that may be mediated by these defects. We perform Nudged Elastic Band (NEB) calculations to determine different diffusion paths for this interface system. Our aim is to predict dominant diffusion mechanisms at the Ni/Sapphire interface using the present analysis.