# Synthesis, Structure, and Thermal Expansion of Triple Phosphates of Potassium–Strontium–Rare Earth Elements

Authors
• 1 National Research Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603950, Russia , Nizhny Novgorod (Russia)
• 2 Moscow State University, Moscow, 119991, Russia , Moscow (Russia)
Type
Published Article
Journal
Russian Journal of Inorganic Chemistry
Publisher
Publication Date
Jun 29, 2021
Volume
66
Issue
6
Pages
799–805
Identifiers
DOI: 10.1134/S0036023621060152
Source
Springer Nature
Keywords
Disciplines
• Synthesis and Properties of Inorganic Compounds
AbstractPolycrystalline phases of variable composition KxSr12 – 2xR4 +x(PO4)12 (R = Nd, Eu, and Gd; 0 ≤ x ≤ 4) with the structure of the mineral eulytite (space group I\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\overline 4$$\end{document}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: αа = αb = αc = (9−12) × 10−6 K−1 without undergoing polymorphic transitions.