Local Structure of Sodium- and Iron-deintercalated NaFeAs
Local Structure of Sodium- and Iron-deintercalated NaFeAs
复制标题
钠和铁脱嵌的 NaFeAs 的局部结构
DOI：
10.1002/zaac.201400343
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Cassidy S
中科院分区：
文献类型：
--
作者：
Cassidy S
用X射线吸收光谱法对室温下碘脱插得到的nafea亚稳衍生物中Fe和As周围的局部结构进行了探测。由于thcr2si2结构类型中的八坐标位置与Na+半径之间的尺寸不匹配，使得具有缺陷thcr2si2结构的脱嵌产物无法通过传统的高温途径获得，并且结晶性差。X射线吸收近边缘结构（XANES）测量显示FeK边缘的移动与铁氧化到+3氧化态一致。在AsK - edge的XANES特征的变化以及对Fe和AsK - edge的扩展X射线吸收精细结构（EXAFS）数据的分析表明，Fe和As的局部结构只能使用高度缺陷的thcr2si2结构模型来充分建模。这表明Na和Fe从nafea中脱嵌产生NaFe1.7As2，其与相关的铁硒化物K0.8Fe1.6Se2具有局部结构特征。
The local structures around Fe and As were probed using X‐ray absorption spectroscopy in metastable derivatives of NaFeAs obtained by deintercalation of the metals with iodine in THF at room temperature. The deintercalated product with a defective ThCr2Si2structure is unattainable through conventional high temperature routes due to the size‐mismatch between the eight‐coordinate site and the Na+radius in the ThCr2Si2structure type, and is poorly crystalline. X‐ray absorption Near Edge Structure (XANES) measurements show a shift of the FeK‐edge consistent with oxidation of iron to the +3 oxidation state. Changes to the features in the XANES at the AsK‐edge and analysis of the Extended X‐ray Absorption Fine Structure (EXAFS) data from both Fe and AsK‐edges show that the local structures of Fe and As may only be modelled adequately using a highly defective ThCr2Si2structural model. This shows that deintercalation of both Na and Fe from NaFeAs occurs to produce NaFe1.7As2, which shares local structural features with the related iron selenides K0.8Fe1.6Se2.