On the Complex Structural Picture of the Ionic Conductor Sr6Ta2O11

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• 作者：Niina Jalarvo ; Simone Casolo ; Nadir Aliouane ; Dirk Wallacher ; Ole Martin L酶vvik ; Truls Norby
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：May 16, 2013
• 年：2013
• 卷：117
• 期：19
• 页码：9543-9549
• 全文大小：410K
• 年卷期：v.117,no.19(May 16, 2013)
• ISSN：1932-7455

文摘

Sr₆Ta₂O₁₁ presents an interesting model system of a highly defective and disordered complex perovskite, exhibiting oxide ion conductivity at high temperatures as well as proton conductivity when hydrated by presence of water vapor. In this paper, we present a comprehensive structural study of Sr₆Ta₂O₁₁ in its dry and hydrated state, based on DFT calculations and NPD measurements. At low temperatures, dry Sr₆Ta₂O₁₁ has a tetragonal symmetry with ordered oxygen vacancies. The oxygen vacancy induces perturbations to its near surroundings, disturbing particularly the A site cations. As a consequence, the elaborate structural picture collapses at higher temperatures. The high-temperature structure has a cubic symmetry with fractionally occupied structural oxygen sites and disorder on the oxygen and strontium sublattices. The structure of the fully hydrated compound Sr₆Ta₂O₁₀(OH)₂ was determined as monoclinic with significant distortions of the anion and metal cation sites.