Abstract

Polycrystalline phases of variable composition K_xSr_{12 – 2x}R_{4 + x}(PO₄)₁₂ (R = Nd, Eu, and Gd; 0 ≤ x ≤ 4) with the structure of the mineral eulytite (space group I\(\overline 4 \)3d) have been synthesized by evaporation of the salt solution followed by heat treatment. Their structures have been studied by X-ray powder diffraction and IR spectroscopy, and electron probe studies have been carried out. The structure of KSr₁₀Eu₅(PO₄)₁₂ has been refined; it has been found that the neutral framework is formed by edge-linked metal-oxygen octahedra (K,Sr,Eu)O₆ with PO₄ tetrahedra located between them and attached to the octahedra by oxygen vertices. At temperature change, phosphates expand uniformly in all directions: α_а = α_b = α_c = (9−12) × 10⁻⁶ K⁻¹ without undergoing polymorphic transitions.

中文翻译：

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钾-锶-稀土元素三重磷酸盐的合成、结构和热膨胀

摘要

具有可变成分 K _x Sr _{12 – 2 x} R _{4 + x} (PO ₄ ) ₁₂ (R = Nd、Eu 和 Gd；0 ≤  x  ≤ 4) 的多晶相，具有矿物钠沸石的结构（空间群I \( \overline 4 \) 3 d ) 已经通过蒸发盐溶液然后热处理合成。已经通过 X 射线粉末衍射和红外光谱研究了它们的结构，并进行了电子探针研究。KSr ₁₀ Eu ₅ (PO ₄ ) _{12 的结构}已经精炼；已经发现中性骨架由边缘连接的金属-氧八面体 (K,Sr,Eu)O _{6 形成}，PO ₄四面体位于它们之间并通过氧顶点连接到八面体。在温度变化时，磷酸盐在各个方向均匀膨胀：α _а = α _b = α _c = (9−12) × 10 ^-6 K ^-1而不发生多晶型转变。