Sr₈[Al₁₂O₂₄](SO₄)₂ (SAS) and Ca₈[Al₁₂O₂₄](SO₄)₂ (CAS) are members of the aluminate sodalite‐type oxides with the general chemical formula M₈[Al₁₂O₂₄](XO₄)₂ (M²⁺ is the guest cation and XO₄²⁻ is the guest anion). To discuss the role of the guest cations (M²⁺ = Sr²⁺ and Ca²⁺) on the rotation of AlO₄ in the oxygen tetrahedral framework in the I43m phase, the crystal structure parameters and the probability density function of the guest ions in SAS and CAS have been investigated via synchrotron radiation X‐ray powder diffraction by considering Gram–Charlier expansions. The interatomic distances between the M²⁺ and O²⁻ ions evaluated from the maximum positions in the probability density distribution are almost equal to the sum of the ideal ionic radii of the M²⁺ and O²⁻ ions. This result suggests that the geometry of the AlO₄ tetrahedral framework and the fluctuation of the guest ions are mainly caused by steric effects between the M²⁺ and O²⁻ ions.

中文翻译：

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I43m相中铝酸钠方钠型氧化物M8 [Al12O24]（SO4）2（M = Sr2 +和Ca2 +）中客体阳离子对AlO4骨架的尺寸效应

Sr ₈ [Al ₁₂ O ₂₄ ]（SO ₄）₂（SAS）和Ca ₈ [Al ₁₂ O ₂₄ ]（SO ₄）₂（CAS）是铝酸盐方钠石型氧化物的分子，其化学通式为M ₈ [ Al ₁₂ O ₂₄ ]（X O ₄）₂（M ²⁺是客体阳离子，X O ₄ ^2-是客体阴离子）。讨论客体阳离子的作用（M ²⁺ = Sr在I 4 3 m相中，在氧气四面体骨架中AlO ₄旋转时²⁺和Ca ²⁺），通过同步加速器辐射X研究了SAS和CAS中客体离子的晶体结构参数和概率密度函数通过考虑格兰-夏利尔展开对粉末进行衍射分析。从概率密度分布中的最大位置估算的M ²⁺和O ^2-离子之间的原子间距离几乎等于M ²⁺和O ^2-的理想离子半径之和离子。该结果表明，AlO ₄四面体骨架的几何形状和客体离子的波动主要是由M ²⁺和O ^2-离子之间的空间效应引起的。