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Cooperative mechanisms of oxygen vacancy stabilization and migration in the isolated tetrahedral anion Scheelite structure.
Nature Communications ( IF 14.7 ) Pub Date : 2018-10-26 , DOI: 10.1038/s41467-018-06911-w
Xiaoyan Yang , Alberto J. Fernández-Carrión , Jiehua Wang , Florence Porcher , Franck Fayon , Mathieu Allix , Xiaojun Kuang

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 BiVO4 Scheelite structure through Sr2+ for Bi3+ substitution, leading to corner-sharing V2O7 tetrahedral dimers, and migrate via a cooperative mechanism involving V2O7-dimer breaking and reforming assisted by synergic rotation and deformation of neighboring VO4 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.

中文翻译:

氧空位稳定和迁移在孤立的四面体阴离子Scheelite结构中的合作机制。

由于其很大的变形和旋转灵活性,四面体单元可以通过间隙或空位缺陷传输氧化物阴离子。与间隙缺陷相比,基于四面体的结构中空位介导的氧化物离子传导更困难并且很少发生。分离的四面体阴离子Scheelite结构具有传导氧间隙的优势,但几乎无法将氧空位引入Scheelite来促进氧化物离子迁移。在这里,我们证明了氧空位可在BiVO稳定4白钨矿结构的Sr通过2+为毕3+置换,导致共角V 2 ö 7四面体二聚体,并通过协同机制迁移,该机制涉及V 2 O 7-二聚体的断裂和重整,并由相邻VO 4四面体的协同旋转和变形辅助。这一发现揭示了白钨矿结构通过空位或间隙传输氧化物离子的能力,强调了在相同的基于四面体的结构类型中开发具有平行空位和间隙掺杂策略的氧化物离子导体的可能性。
更新日期:2018-10-26
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