Local Structure of Proton-Conducting Lanthanum Tungstate La28-xW4+xO54+δ: a Combined Density Functional Theory and Pair Distribution Function Study
Local Structure of Proton-Conducting Lanthanum Tungstate La28-xW4+xO54+δ: a Combined Density Functional Theory and Pair Distribution Function Study
复制标题
质子传导钨酸镧La28-xW4+xO54+δ的局域结构：密度泛函理论和对分布函数的结合研究
DOI：
10.1021/cm401466r
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
L. Malavasi
中科院分区：
文献类型：
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作者：
Liv;A. Magrasó;A. Mancini;C. Tealdi;L. Malavasi
钨酸镧（La 28-xW 4 + xO 54 +δ）是一种良好的质子导体，具有复杂的萤石型结构。为了进一步了解结构中的短程有序，我们将通过密度泛函理论（DFT）获得的优化配置与在室温下收集的飞行时间中子和同步辐射X射线数据的实验原子对分布函数分析（PDF）相关联。局部原子排列不能用任何平均对称结构来描述。钨以交替方向形成WO 6八面体，La 1主要在相对对称的立方体中以8重配位，而La 2在严重扭曲的立方体中与6或7个氧配位。DFT和PDF都证实了过量的钨（x）结合在La27W5O55.5组成中的La 2（1/4，1/4，1/4）位点中。这种额外的钨可以被认为是材料中的施主自掺杂剂，并且对导电性质和缺陷结构具有影响。
Lanthanum tungstate (La28–xW4+xO54+δ) is a good proton conductor and exhibits a complex fluorite-type structure. To gain further understanding of the short-range order in the structure we correlate the optimized configurations obtained by density functional theory (DFT) with the experimental atomic pair distribution function analysis (PDF) of time-of-flight neutron and synchrotron X-ray data, collected at room temperature. The local atomic arrangements cannot be described by means of any average symmetric structure. Tungsten forms WO6 octahedra in alternating directions, La1 is mainly 8-fold coordinated in relatively symmetric cubes, and La2 is coordinated with 6 or 7 oxygens in heavily distorted cubes. Both DFT and PDF confirm that the excess tungsten (x) is incorporated in La2 (1/4, 1/4, 1/4) sites in the La27W5O55.5 composition. This additional tungsten can be considered as a donor self-dopant in the material and has implications to the conducting properties and the defect structure.