Cooperative mechanisms of oxygen vacancy stabilization and migration in the isolated tetrahedral anion Scheelite structure.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30367043.
- Also identified by DOI 10.1038/s41467-018-06911-w and PMC identifier 6203716.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Tetrahedral units can transport oxide anions via interstitial or vacancy defects owing to their great deformation and rotation flexibility. Compared with interstitial defects, vacancy-mediated oxide-ion conduction in tetrahedra-based structures is more difficult and occurs rarely. The isolated tetrahedral anion Scheelite structure has showed the advantage of conducting oxygen interstitials but oxygen vacancies can hardly be introduced into Scheelite to promote the oxide ion migration. Here we demonstrate that oxygen vacancies can be stabilized in the BiVO<sub>4</sub> Scheelite structure through Sr<sup>2+</sup> for Bi<sup>3+</sup> substitution, leading to corner-sharing V<sub>2</sub>O<sub>7</sub> tetrahedral dimers, and migrate via a cooperative mechanism involving V<sub>2</sub>O<sub>7</sub>-dimer breaking and reforming assisted by synergic rotation and deformation of neighboring VO<sub>4</sub> tetrahedra. This finding reveals the ability of Scheelite structure to transport oxide ion through vacancies or interstitials, emphasizing the possibility to develop oxide-ion conductors with parallel vacancy and interstitial doping strategies within the same tetrahedra-based structure type.