Exploring the interplay between electronic doping, magnetism, and Ni diffusion in NiO from first principles.

NiO and NiO solid solutions are typically the first passivating oxides to form during the corrosion of Ni-rich alloys. Ni diffusion from the alloy interface, through the oxide, to the exposed surface is the rate-limiting kinetic process for continued oxidation. From first principles, we calculate the effects of magnetic order and electronic doping on the minimum energy diffusion pathways. We elucidate the origin of the diffusion barrier dependencies by assessing changes in the defect states and chemical bonding along the diffusion paths. Our work highlights the complexity of diffusion in even structural simply but strongly correlated oxides with practical recommendations for corrosion resistance that may be transferable to diffusion-mediated redox processes in energy storage materials.