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Abstract <p>Silicophosphates A<sub>2</sub>Zr<sub>2</sub>SiO<sub>4</sub>(PO<sub>4</sub>)<sub>2</sub> (A = K, Rb, and Cs) with langbeinite structure have been synthesized and studied for the first time. The samples have been characterized by XRD, IR spectroscopy, scanning electron microscopy, and energy-dispersive X-ray microanalysis. Single phase silicophosphates have been prepared at 800°C. Refining of crystal structure of Rb<sub>2</sub>Zr<sub>2</sub>SiO<sub>4</sub>(PO<sub>4</sub>)<sub>2</sub> by Rietveld method have shown that the structure is based on 3D framework formed by ZrO<sub>6</sub> octahedra and (Si/P)O<sub>4</sub> tetrahedra, extra-framework alkali metal cations occupy separated cavities within the scaffold. Stretching and bending vibrations of SiO<sub>4</sub> and PO<sub>4</sub> tetrahedra have been determined for the compounds. Correlations between IR spectra and the nature of cation A<sup>+</sup> have been revealed. Thermal stability of silicophosphates up to 1200°C has been confirmed by thermal X-ray diffraction and combined TG–DSC analysis. The linear thermal expansion coefficient of Cs<sub>2</sub>Zr<sub>2</sub>SiO<sub>4</sub>(PO<sub>4</sub>)<sub>2</sub> has been found to be α<sub><i>a</i></sub> = 5.8 × 10<sup>–6</sup> K<sup>–1</sup>. The obtained results allow one to conclude that the studied silicophosphate materials are highly persistent to extreme temperature conditions.</p>

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Synthesis, Structure, and Thermal Properties of Zirconium and Alkali Metal (K, Rb, and Cs) Silicophosphates

  • 期刊论文

  • 发表日期：

    2025年9月1日

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  • V. I. Pet’kov,
  • E. A. Asabina,
  • A. V. Lapin,
  • N. S. Kulikova,
  • A. S. Ganov

摘要

Abstract

Silicophosphates A2Zr2SiO4(PO4)2 (A = K, Rb, and Cs) with langbeinite structure have been synthesized and studied for the first time. The samples have been characterized by XRD, IR spectroscopy, scanning electron microscopy, and energy-dispersive X-ray microanalysis. Single phase silicophosphates have been prepared at 800°C. Refining of crystal structure of Rb2Zr2SiO4(PO4)2 by Rietveld method have shown that the structure is based on 3D framework formed by ZrO6 octahedra and (Si/P)O4 tetrahedra, extra-framework alkali metal cations occupy separated cavities within the scaffold. Stretching and bending vibrations of SiO4 and PO4 tetrahedra have been determined for the compounds. Correlations between IR spectra and the nature of cation A+ have been revealed. Thermal stability of silicophosphates up to 1200°C has been confirmed by thermal X-ray diffraction and combined TG–DSC analysis. The linear thermal expansion coefficient of Cs2Zr2SiO4(PO4)2 has been found to be αa = 5.8 × 10–6 K–1. The obtained results allow one to conclude that the studied silicophosphate materials are highly persistent to extreme temperature conditions.