In this comparative study, two samples with a slightly different oxygen : metal ratio have been characterized by various electron microscopy methods and by single‐crystal and powder X‐ray diffraction (XRD). A reasonably good fit to the experimental powder XRD patterns could be achieved by Rietveld refinement for both samples Nb₈W₉O₄₇ and Nb₇W₁₀O_47.5 using the structural models of Nb_6.7W_10.3O₄₇ and Nb₈W₉O₄₇ both obtained from X‐ray crystal structure analysis. HRTEM investigations confirm that Nb₈W₉O₄₇ crystallizes as a pure phase in the well‐known threefold superstructure of the tetragonal tungsten bronze type (TTB). In contrast, a more complex real structure was found for the sample Nb₇W₁₀O_47.5 with small domains of Nb₄W₇O₃₁ appearing besides large ones of Nb₈W₉O₄₇ and in addition extended TTB‐based areas with short‐range order only. The diffuse scattering caused by this disorder is easily detected in the electron diffraction pattern but does not affect the Rietveld refinement of the powder XRD patterns. However, on the basis of powder diffraction experiments, it is clearly possible to distinguish between the above compounds and the hypothetical, but non‐existing compound “Nb₁₈W₁₆O₉₃”, a composition recently postulated for battery materials.

中文翻译：

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四方钨青铜型铌钨氧化物的结构复杂性

在这项比较研究中，通过各种电子显微镜方法以及单晶和粉末X射线衍射（XRD）表征了两个氧，金属比例稍有不同的样品。通过使用Nb _6.7 W _10.3 O ₄₇和Nb ₈ W ₉ O ₄₇的结构模型，对样品Nb ₈ W ₉ O ₄₇和Nb ₇ W ₁₀ O _47.5进行Rietveld精修，可以达到对粉末XRD实验图案的合理良好拟合。两者均从X射线晶体结构分析获得。HRTEM研究证实Nb ₈ W₉ O ₄₇在四方钨青铜型（TTB）的众所周知的三重上部结构中结晶为纯相。相反，对于样品Nb ₇ W ₁₀ O _47.5，发现了更复杂的真实结构，除了大的Nb ₈ W ₉ O ₄₇以外，还出现了小的Nb ₄ W ₇ O ₃₁畴。另外，扩展的基于TTB的区域仅具有短程订单。在电子衍射图上很容易检测到由这种紊乱引起的扩散散射，但不会影响粉末XRD图的Rietveld细化。但是，根据粉末衍射实验，显然可以区分上述化合物和假设的但不存在的化合物“ Nb ₁₈ W ₁₆ O ₉₃ ”，该化合物最近被假定为电池材料。