The Crystal Structure of α-La2Mo2O9 and the Structural Origin of the Oxide Ion Migration Pathway

摘要: We describe for the first time full 3D atomic structure of room-temperature α-La2Mo2O9. The material, despite its simple chemical formula, has a remarkable 312 crystallographically unique atoms and is thus one most complex oxide structures reported to date. Despite this complexity, structural results offer significant insight into O2- migration pathway in anion conducting high-temperature form, β-La2Mo2O9. material contains mixture 4, 5, 6 coordinated Mo sites, suggesting that variable coordination number key factor providing low-energy conduction pathway. provide quantitative analysis showing positions ordered array 216 oxygen sites α-La2Mo2O9 are directly related average occupied β-La2Mo2O9, compelling evidence form time-averaged version low-temperature structure.