document: At 200 – 300°C: nuclear densities are localised in the tetrahedral volume roughly covering the 8c and 32f positions with “bulges” of nuclear densities pointing toward the 48i position, while at 400 and 500°C continuous nuclear densities forming a straight line along the <100> direction are found, indicative of oxide-ion diffusion pathway along that direction. In the literature, curved pathways along the <100> direction passing through the 48i site are generally observed in fluorite materials [20], the prevalence of curve pathway as opposed from straight pathway is explained by the repulsion between cation and anions, the curved pathway allowing the cation–anion to maintain a reasonable distance. However, a straight pathway is observed for Y0.785Ta0.215O1.715 [23], as is the case for the present material. This suggests that Ta and Re cations might play a similar role in these systems.
doc_bio_tags: O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O B O B O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O B I I I O O O O O O O O
extractive_keyphrases: anions “bulges” cation fluorite materials present material ta and re cations
abstractive_keyphrases: anion ion oxide oxide-ion diffusion