MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materials, Guangxi University Key Laboratory of Nonferrous Metal Oxide Electronic Functional Materials and Devices, College of Materials Science and Engineering, Guilin University of Technology, Guilin, Guangxi, 541004, People's Republic of China.
CNRS, CEMHTI UPR3079, Univ. Orléans, 45071, Orléans, France.
Nat Commun. 2018 Oct 26;9(1):4484. doi: 10.1038/s41467-018-06911-w.
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 Scheelite structure through Sr for Bi substitution, leading to corner-sharing VO tetrahedral dimers, and migrate via a cooperative mechanism involving VO-dimer breaking and reforming assisted by synergic rotation and deformation of neighboring VO 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.
四面体单元由于其大的变形和旋转灵活性，可以通过间隙或空位缺陷来传输氧化物阴离子。与间隙缺陷相比，四面体基结构中的空位介导的氧化物离子传导更困难且很少发生。孤立的四面体阴离子白钨矿结构表现出传导氧间隙的优势，但氧空位很难引入白钨矿中以促进氧化物离子迁移。在这里，我们证明通过 Sr 取代 Bi 可以在 BiVO4 白钨矿结构中稳定氧空位，形成顶角共享 VO4 四面体二聚体，并通过 VO4 二聚体的断裂和形成来迁移，这一过程由协同的旋转和变形辅助，涉及相邻 VO4 四面体。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内通过空位和间隙掺杂策略来开发氧化物离子导体的可能性。
