THERMODYNAMICALLY STABLE PHASES OF THE Ag9GaSe6 – Ag8GeSe6 SYSTEM AT T

The synthesis of thermodynamically stable phases of the Ag9GaSe6–Ag8GeSe6 (І) system at T<600 K were performed in the electrochemi­cal cells (ECCs): (−) С | Ag | SЕ | R(Ag+) | PЕ |&...

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Date:2022
Main Authors: Moroz, Mykola, Demchenko, Pavlo, Prohorenko, Myroslava, Soliak, Ludmila, Prohorenko, Serhii, Reshetnyak, Oleksandr
Format: Article
Language:English
Published: V.I.Vernadsky Institute of General and Inorganic Chemistry 2022
Online Access:https://ucj.org.ua/index.php/journal/article/view/449
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spelling oai:ojs2.1444248.nisspano.web.hosting-test.net:article-4492022-08-16T11:52:47Z THERMODYNAMICALLY STABLE PHASES OF THE Ag9GaSe6 – Ag8GeSe6 SYSTEM AT T Moroz, Mykola Demchenko, Pavlo Prohorenko, Myroslava Soliak, Ludmila Prohorenko, Serhii Reshetnyak, Oleksandr Ag-containing compounds, Thermodynamic properties, Phase equilibria, Metastable state, EMF method. The synthesis of thermodynamically stable phases of the Ag9GaSe6–Ag8GeSe6 (І) system at T<600 K were performed in the electrochemi­cal cells (ECCs): (−) С | Ag | SЕ | R(Ag+) | PЕ | С (+), where C is graphite, Ag is the left (negative) electrode, SE is the purely Ag+ ion conducting solid electrolyte (Ag2GeS3-glass), PE is the right (positive) electrode, and R(Ag+) is the region of PE that contact with SE. PEs of ECCs were prepared from finely ground non-equilibrium mixtures of the compounds (Ag9GaSe6)1–х and (Ag8GeSe6)х, х=0.05, 0.1, 0.2, … , 0.9. Shifted from the left electrode to the R(Ag+) region for thermodynamic reasons Ag+ ions acted as the nucleation centers for the equilibrium phases of the x compositions, that is as the catalysts for reconstruction of the metastable mixtures of ternary compounds. The reproducibility of the EMF vs T dependences in the heating-cooling cycles is a result of the completion of reconstruction in the R(Ag+) region. Experimental dependences EMF vs T of ECCs with PE of mixtures of compounds indicated x, ECCs with PE of the Ag9GaSe6 and Ag8GeSe6 compounds are charac­terized by several discrete linear regions with different temperature intervals and functional dependences on temperature. The equations of the temperature dependences of the partial Gibbs energies of Ag-component in alloys for each discrete section of the specific x=0, 0.3, 0.5, 0.7, 1.0 were established for the first time and values of the standard partial functions  were calculated. The bypass lines drawn through the points of EMF values of the cells at T=const for arbitrarily selected temperatures 298 K, 341 K, 395 K, 445 K, and 495 K in the range 280-500 K determine the phase composition of the equilibrium T-x space of (I) as: a solid solution based on compound Ag17GaGeSe12 in the range of 0.25≤x≤0.75, solid solutions based on the compounds (Ag9GaSe6)1–х for 0≤х≤0.15 and (Ag8GeSe6)х for 0.83≤х≤1, and two two-phase sections in the ranges 0.15≤x≤0.25 and 0.73≤x≤0.77. Some parameters of the crystal structure, the values of the total and ionic components of conductivity, the transfer numbers in the range of 290–380 K, and the integral va­lues of the standard thermodynamic functions of the Ag17GaGeSe12 compound were established for the first time. V.I.Vernadsky Institute of General and Inorganic Chemistry 2022-06-24 Article Article Physical chemistry Физическая xимия Фізична xімія application/pdf https://ucj.org.ua/index.php/journal/article/view/449 10.33609/2708-129X.88.05.2022.25-36 Ukrainian Chemistry Journal; Vol. 88 No. 5 (2022): Ukrainian Chemistry Journal; 25-36 Украинский химический журнал; Том 88 № 5 (2022): Ukrainian Chemistry Journal; 25-36 Український хімічний журнал; Том 88 № 5 (2022): Український хімічний журнал; 25-36 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/449/227
institution Ukrainian Chemistry Journal
baseUrl_str
datestamp_date 2022-08-16T11:52:47Z
collection OJS
language English
topic_facet Ag-containing compounds
Thermodynamic properties
Phase equilibria
Metastable state
EMF method.
format Article
author Moroz, Mykola
Demchenko, Pavlo
Prohorenko, Myroslava
Soliak, Ludmila
Prohorenko, Serhii
Reshetnyak, Oleksandr
spellingShingle Moroz, Mykola
Demchenko, Pavlo
Prohorenko, Myroslava
Soliak, Ludmila
Prohorenko, Serhii
Reshetnyak, Oleksandr
THERMODYNAMICALLY STABLE PHASES OF THE Ag9GaSe6 – Ag8GeSe6 SYSTEM AT T
author_facet Moroz, Mykola
Demchenko, Pavlo
Prohorenko, Myroslava
Soliak, Ludmila
Prohorenko, Serhii
Reshetnyak, Oleksandr
author_sort Moroz, Mykola
title THERMODYNAMICALLY STABLE PHASES OF THE Ag9GaSe6 – Ag8GeSe6 SYSTEM AT T
title_short THERMODYNAMICALLY STABLE PHASES OF THE Ag9GaSe6 – Ag8GeSe6 SYSTEM AT T
title_full THERMODYNAMICALLY STABLE PHASES OF THE Ag9GaSe6 – Ag8GeSe6 SYSTEM AT T
title_fullStr THERMODYNAMICALLY STABLE PHASES OF THE Ag9GaSe6 – Ag8GeSe6 SYSTEM AT T
title_full_unstemmed THERMODYNAMICALLY STABLE PHASES OF THE Ag9GaSe6 – Ag8GeSe6 SYSTEM AT T
title_sort thermodynamically stable phases of the ag9gase6 – ag8gese6 system at t
description The synthesis of thermodynamically stable phases of the Ag9GaSe6–Ag8GeSe6 (І) system at T<600 K were performed in the electrochemi­cal cells (ECCs): (−) С | Ag | SЕ | R(Ag+) | PЕ | С (+), where C is graphite, Ag is the left (negative) electrode, SE is the purely Ag+ ion conducting solid electrolyte (Ag2GeS3-glass), PE is the right (positive) electrode, and R(Ag+) is the region of PE that contact with SE. PEs of ECCs were prepared from finely ground non-equilibrium mixtures of the compounds (Ag9GaSe6)1–х and (Ag8GeSe6)х, х=0.05, 0.1, 0.2, … , 0.9. Shifted from the left electrode to the R(Ag+) region for thermodynamic reasons Ag+ ions acted as the nucleation centers for the equilibrium phases of the x compositions, that is as the catalysts for reconstruction of the metastable mixtures of ternary compounds. The reproducibility of the EMF vs T dependences in the heating-cooling cycles is a result of the completion of reconstruction in the R(Ag+) region. Experimental dependences EMF vs T of ECCs with PE of mixtures of compounds indicated x, ECCs with PE of the Ag9GaSe6 and Ag8GeSe6 compounds are charac­terized by several discrete linear regions with different temperature intervals and functional dependences on temperature. The equations of the temperature dependences of the partial Gibbs energies of Ag-component in alloys for each discrete section of the specific x=0, 0.3, 0.5, 0.7, 1.0 were established for the first time and values of the standard partial functions  were calculated. The bypass lines drawn through the points of EMF values of the cells at T=const for arbitrarily selected temperatures 298 K, 341 K, 395 K, 445 K, and 495 K in the range 280-500 K determine the phase composition of the equilibrium T-x space of (I) as: a solid solution based on compound Ag17GaGeSe12 in the range of 0.25≤x≤0.75, solid solutions based on the compounds (Ag9GaSe6)1–х for 0≤х≤0.15 and (Ag8GeSe6)х for 0.83≤х≤1, and two two-phase sections in the ranges 0.15≤x≤0.25 and 0.73≤x≤0.77. Some parameters of the crystal structure, the values of the total and ionic components of conductivity, the transfer numbers in the range of 290–380 K, and the integral va­lues of the standard thermodynamic functions of the Ag17GaGeSe12 compound were established for the first time.
publisher V.I.Vernadsky Institute of General and Inorganic Chemistry
publishDate 2022
url https://ucj.org.ua/index.php/journal/article/view/449
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