Abstract

A crystallographic analysis of hexagonal poudretteite (KNa₂B₃Si₁₂O₃₀, symmetry P6/mcc) and cubic pollucite (CsAlSi₂O₆, Ia\(\bar {3}\)d) has revealed characteristic features of two versions of energetically stable atomic configurations, which are abundant among natural and synthesized inorganic compounds. These are structures with a minimum number of parameters (not fixed by the symmetry of basis-atom coordinates) and minimum volumes V* of independent parts of unit cells. The structures of silicates with a large number of tetrahedral cations exhibit a symmetry of glide planes and screw axes, which provides both stability and close packing of topologically connected fragments (templates) of these structures.

中文翻译：

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关于无机化合物晶体结构的两个高度对称的模具

摘要

六方磷灰石（KNa ₂ B ₃ Si ₁₂ O ₃₀，对称性P 6 / mcc）和立方晶石（CsAlSi ₂ O ₆，Ia \（\ bar {3} \）d）的晶体学分析揭示了两种形式的特征能量稳定的原子构型，在天然和合成的无机化合物中丰富。这些结构具有最少数量的参数（不受基原子坐标的对称性固定）和最小体积V*晶胞的独立部分。具有大量四面体阳离子的硅酸盐结构表现出滑行面和螺旋轴的对称性，这提供了稳定性以及这些结构的拓扑连接片段（模板）的紧密堆积。