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Thermodynamic Characteristics of Zinc Niobates Zn3Nb2O8, ZnNb2O6, and Zn2Nb34O87. p–x Diagram of the ZnO–Nb2O5 System

Authors
  • Gribchenkova, N. A.1
  • Smirnov, A. S.1
  • Smorchkov, K. G.1
  • Belova, E. V.1
  • Alikhanyan, A. S.1
  • 1 Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow, 119991, Russia , Moscow (Russia)
Type
Published Article
Journal
Russian Journal of Inorganic Chemistry
Publisher
Pleiades Publishing
Publication Date
Dec 14, 2021
Volume
66
Issue
12
Pages
1873–1879
Identifiers
DOI: 10.1134/S0036023621120044
Source
Springer Nature
Keywords
Disciplines
  • Physicochemical Analysis of Inorganic Systems
License
Yellow

Abstract

AbstractVapor formation in the ZnO–Nb2O5 system in the range 1223–1465 K was studied by Knudsen effusion mass spectrometry. Over the entire range of condensed phase compositions, the saturated vapor above the system consists of zinc atoms, oxygen molecules, and a small amount of ZnO molecules. The absolute component partial vapor pressures and activities were calculated. The р–х section of the global р–Т–х phase diagram at 1353 and 1443 K was plotted. The second-law and third-law values were determined of the standard enthalpies of selected heterophase reactions and the standard enthalpies of formation zinc niobates: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\Delta }_{f}}H_{{298}}^{^\circ }$$\end{document}(Zn3Nb2O8) = –2992.0 ± 30.2 kJ/mol, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\Delta }_{f}}H_{{298}}^{^\circ }$$\end{document}(ZnNb2O6) = –2292.4 ± 19.9 kJ/mol, and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\Delta }_{f}}H_{{298}}^{^\circ }$$\end{document}(Zn2Nb34O87) = –33056.1 ± 15.0 kJ/mol, and their enthalpies of formation from simple oxides: (Zn3Nb2O8) = –50.0 ± 20.0 kJ/mol, (ZnNb2O6) = –40.5 ± 15.0 kJ/mol, and (Zn2Nb34O87) = –90.9 ± 15.0 kJ/mol.

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