The leucite tectosilicate mineral analogues K₂X²⁺Si₅O₁₂ (X = Fe²⁺, Co, Zn) and Rb₂X²⁺Si₅O₁₂ (X = Mn) have been synthesized at elevated temperatures both dry at atmospheric pressure and at controlled water vapour pressure; for X = Co and Zn both dry and hydrothermally synthesized samples are available. Rietveld refinement of X‐ray data for hydrothermal K₂X²⁺Si₅O₁₂ (X = Fe²⁺, Co, Zn) samples shows that they crystallize in the monoclinic space group P2₁/c and have tetrahedral cations (Si and X) ordered onto distinct framework sites [cf. hydrothermal K₂MgSi₅O₁₂; Bell et al. (1994a), Acta Cryst. B50, 560–566]. Dry‐synthesized K₂X²⁺Si₅O₁₂ (X = Co, Zn) and Rb₂X²⁺Si₅O₁₂ (X = Mn) samples crystallize in the cubic space group and with Si and X cations disordered in the tetrahedral framework sites as typified by dry K₂MgSi₅O₁₂. Both structure types have tetrahedrally coordinated SiO₄ and XO₄ sharing corners to form a partially substituted silicate framework. Extraframework K⁺ and Rb⁺ cations occupy large channels in the framework. Structural data for the ordered samples show that mean tetrahedral Si—O and X—O bond lengths cover the ranges 1.60 Å (Si—O) to 2.24 Å (Fe²⁺—O) and show an inverse relationship with the intertetrahedral angles (T—O—T) which range from 144.7° (Si—O—Si) to 124.6° (Si—O—Fe²⁺). For the compositions with both disordered and ordered tetrahedral cation structures (K₂MgSi₅O₁₂, K₂CoSi₅O₁₂, K₂ZnSi₅O₁₂, Rb₂MnSi₅O₁₂ and Cs₂CuSi₅O₁₂ leucites) the disordered polymorphs always have larger unit‐cell volumes, larger intertetrahedral T—O—T angles and smaller mean T—O distances than their isochemical ordered polymorphs. The ordered samples clearly have more flexible frameworks than the disordered structures which allow the former to undergo a greater degree of tetrahedral collapse around the interframework cavity cations. Multivariant linear regression has been used to develop equations to predict intertetrahedral T—O—T angle variation depending on the independent variables Si—O and X—O bond lengths, cavity cation ideal radius, intratetrahedral (O—T—O) angle variance, and X cation electronegativity.

中文翻译：

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K2 [XSi5O12]（X = Fe2 +，Co，Zn）和Rb2 [XSi5O12]（X = Mn）白云母的晶体结构：单斜晶P21 / c和Ia {\ overline 3} d多晶型结构的比较以及四面体阳离子之间的反比关系（T = Si和X）-O键距和四面体TOT角。

白云母硅酸盐硅酸盐矿物类似物K ₂ X ²⁺ Si ₅ O ₁₂（X = Fe 2 ⁺，Co，Zn）和Rb ₂ X ²⁺ Si ₅ O ₁₂（X = Mn）都是在高温下合成的。压力和受控的水蒸气压力；对于X = Co和Zn，可以使用干法和水热法合成的样品。水热K ₂ X ²⁺ Si ₅ O ₁₂（X = Fe ^2+）的X射线数据的Rietveld修正，钴，锌）的样品显示，它们的单斜空间群结晶P 2 ₁ / ç并四面体阳离子（Si和X）有序到不同框架位点[比照 水热K ₂ MgSi ₅ O ₁₂ ; 贝尔等。（1994 a），Acta Cryst。乙50，560-566]。干法合成的K ₂ X ²⁺ Si ₅ O ₁₂（X = Co，Zn）和Rb ₂ X ²⁺ Si ₅ O ₁₂（X = Mn）样品在立方空间群中结晶，并且Si和X阳离子在四面体骨架位点无序，以干燥的K ₂ MgSi ₅ O ₁₂为代表。两种结构类型均具有四面配位的SiO ₄和X O ₄共享角，以形成部分取代的硅酸盐骨架。框架外K ⁺和Rb ⁺阳离子在框架中占据较大的通道。有序样品的结构数据表明，平均四面体Si-O和X -O键长覆盖1.60Å（Si-O）至2.24Å（Fe ²⁺-O）并显示与介于144.7°（Si-O-Si）至124.6°（Si-O-Fe ²⁺）的四面体角（T -O- T）成反比的关系。对于具有无序和有序四面体阳离子结构（K ₂ MgSi ₅ O ₁₂，K ₂ CoSi ₅ O ₁₂，K ₂ ZnSi ₅ O ₁₂，Rb ₂ MnSi ₅ O ₁₂和Cs ₂ CuSi ₅ O _{12）的组合物}白云母）无序多晶型物始终比等化学有序多晶型物具有更大的晶胞体积，更大的四面体T -O- T角和更小的平均T -O距离。与无序结构相比，有序样品显然具有更灵活的框架，这使前者在框架间空腔阳离子周围经历更大程度的四面体塌陷。多变量线性回归已用于开发方程式，以预测四面体之间的T -O- T角度变化，具体取决于自变量Si-O和X -O键长，腔阳离子理想半径，四面体（OT - O）角度变化，和X 阳离子电负性。