Scholarlink

Abstract <p>A holotype sample of keldyshite has been studied. It was found to consist of aggregates of partially protonated, Na-deficient parakeldyshite (which is dominant) and keldyshite itself. A series of laboratory experiments on the hydrolysis of parakeldyshite was performed, as a result of which the crystal structure of the keldyshite formed during this process was refined. A refined idealized formula was proposed for it: (Na<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11445_2025_8162_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">\(\square \)</EquationSource> <!--Cryst2460286Panikorovskii-m1--> </InlineEquation>)ZrSi<sub>2</sub>O<sub>6</sub>(OH). As a result of the protonation of the oxygen atom at the О5 position and formation of strong hydrogen bonds (with an O5…O5 distance of 2.458&#xa0;Å in keldyshite), a series of hinge transformations occurs, causing a significant distortion of the Zr–Si–O framework within the crystal structure. The existence of the transformation series from parakeldyshite to keldyshite in nature is confirmed. The mechanism of keldyshite formation can be described by the reaction scheme Na<sup>+</sup> + O<sup>2−</sup> → <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11445_2025_8162_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">\(\square \)</EquationSource> <!--Cryst2460286Panikorovskii-m2--> </InlineEquation> + (OH)<sup>−</sup>. The substitution reaction of parakeldyshite by keldyshite most likely occurs via a transition from single crystal to single crystal.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Transformation Series Parakeldyshite–Keldyshite: Mechanism of Transformation, Chemical Formula Revision, and Crystal Structure of Keldyshite

  • 期刊论文

  • 发表日期：

    2025年6月1日

查看全文
  • T. L. Panikorovskii,
  • G. O. Samburov,
  • A. P. Nikolaev,
  • A. V. Bazai,
  • O. F. Goichuk,
  • I. V. Pekov,
  • S. V. Krivovichev

摘要

Abstract

A holotype sample of keldyshite has been studied. It was found to consist of aggregates of partially protonated, Na-deficient parakeldyshite (which is dominant) and keldyshite itself. A series of laboratory experiments on the hydrolysis of parakeldyshite was performed, as a result of which the crystal structure of the keldyshite formed during this process was refined. A refined idealized formula was proposed for it: (Na \(\square \) )ZrSi2O6(OH). As a result of the protonation of the oxygen atom at the О5 position and formation of strong hydrogen bonds (with an O5…O5 distance of 2.458 Å in keldyshite), a series of hinge transformations occurs, causing a significant distortion of the Zr–Si–O framework within the crystal structure. The existence of the transformation series from parakeldyshite to keldyshite in nature is confirmed. The mechanism of keldyshite formation can be described by the reaction scheme Na+ + O2− → \(\square \) + (OH)−. The substitution reaction of parakeldyshite by keldyshite most likely occurs via a transition from single crystal to single crystal.