The results of theoretical studies targeted at anion mobility in solid M–Ta–O–N systems were presented. Periodic super-cell calculations at density-functional level were used to investigate the local structures of N-doped tantalum oxides and their anion diffusion mechanisms. The migration pathways and activation barriers were calculated by using the nudged elastic band method with climbing-image enhancement. It was shown that defect migration was caused mainly by the diffusion of O anions. The activation energy could be lowered by increasing the defect concentration and was, to a large extent, dependent upon the dopant size.

Defect Migration in Fluorite-Type Tantalum Oxynitrides - a First-Principles Study. H.Wolff, R.Dronskowski: Solid State Ionics, 2008, 179[21-26], 816-8