Temperature Dependence of Self-Diffusion in Cr 2 O 3 from First Principles

Understanding and predicting the dominant diffusion processes in Cr2O3 are essential to its optimization for anticorrosion coatings, spintronics, and other applications. Despite significant theoretical effort in modeling defect-mediated diffusion in Cr2O3, the correlation with experimentally measured diffusivities remains poor partly due to the insufficient accuracy of the theoretical approaches. Here an attempt to resolve these discrepancies is made through high accuracy density functional theory simulations coupled with grand canonical formalism of defect thermochemistry. In this approach, point defect formation energies were computed using the hybrid exchange correlation functional. This level of theory proved to be essential for achieving the agreement with experimental self-diffusion coefficients. The analysis of the resulting self-diffusion coefficients indicate that chromium has higher mobility at low temperatures and high oxygen partial pressures, in particular at standard temperature and pressure...