Direct Observation of Oxide Ion Dynamics in La2Mo2O9 on the Nanosecond Timescale

作者：Peet Joseph R; Fuller Chloe A; Frick Bernhard; Zbiri Mohamed; Piovano Andrea; Johnson Mark R; Evans Ivana Radosavljevic^*

来源：Chemistry of Materials, 2017, 29(7): 3020-3028.

DOI：10.1021/acs.chemmater.6b05507

Quasielastic neutron scattering (QENS), underpinned by ab initio molecular dynamics (AIMD) simulations, has been used to directly observe oxide ion dynamics in solid electrolyte La2Mo2O9 on the nanosecond timescale, the longest timescale probed in oxide ion conductors by neutron scattering to date. QENS gives the activation energy of 0.61(5) eV for this process, while AIMD simulations reveal that the exchange processes, which ultimately lead to long-range oxide ion diffusion in La2Mo2O9, rely on the flexibility of the coordination environment around Mo6+, with oxide ions jumps occurring between vacant sites both within and between Mo coordination spheres. Simulations also differentiate between the crystallographic sites which participate in the oxide ion exchange processes, offering the first atomic-level understanding of the oxide ion dynamics in La2Mo2O9, which is consistent with the macroscopic experimental observations on this material.

• 出版日期2017-4-11