Symmetry reduction in the basic structure of thortveitite‐type compound FeInGe₂O₇–mC22 (C12/m1, No. 12) promoted by the incorporation of yttrium in the formula FeIn_1−xY_xGe₂O₇ gives rise to a derivative structure called thortveitite‐like AA′Ge₂O₇–mP44, with symmetry described by the space group P12₁/m1 (No. 11) for x = 0.50, 0.75 and 0.90. The structure remains unchanged within the structural type of thortveitite when x = 0.25. In order to establish structural models for performing a Rietveld refinement to the derivative structure, symmetry relations between space groups connecting the basic and derivative structures were used. The higher contrast to X‐rays of Fe³⁺, In³⁺ and Y³⁺ as well as by the behaviour during the refinements of the isotropic thermal displacements, the values of interatomic distances and calculated bond‐valence sums for each atom in the asymmetric unit, were helpful for elucidating the relocation of cations in the different available crystallographic sites generated by the symmetry reduction.

中文翻译：

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FeIn1-xYxGe2O7层状体系中组分诱导的相变和空间群之间的对称关系。

对称性减小thortveitite型的基本结构化合物FeInGe ₂ ö ₇ -三菱商事22（Ç 12 /米由钇的式FEIN中掺入促进1，第12号）_{1- X} ý _X葛₂ ö ₇产生到的衍生物结构称为thortveitite状AA '的Ge ₂ ö ₇ -的mP 44，与由空间群对称性描述P 12 ₁ /米1（第11号），用于X= 0.50、0.75和0.90。当x = 0.25时，在苏云母的结构类型内结构保持不变。为了建立用于对衍生结构进行Rietveld改进的结构模型，使用了连接基本结构和衍生结构的空间组之间的对称关系。Fe ³⁺，In ³⁺和Y ^3+的X射线对比度更高，以及各向同性热位移的细化过程中的行为，原子中原子间的距离值和计算出的键合价和不对称单元，有助于阐明由于对称性还原而产生的不同可用晶体学位点中阳离子的重定位。