The Equilibrium Phase Formation and Thermodynamic Properties of Functional Tellurides in the Ag-Fe-Ge-Te System

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2021-02-28
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Mcode
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Language
en
Pages
15
Series
Energies, Volume 14, issue 5
Abstract
Equilibrium phase formations below 600 K in the parts Ag2Te-FeTe2-F1.12Te-Ag2Te and Ag8GeTe6-GeTe-FeTe2-AgFeTe2-Ag8GeTe6 of the Fe-Ag-Ge-Te system were established by the electromotive force (EMF) method. The positions of 3- and 4-phase regions relative to the composition of silver were applied to express the potential reactions involving the AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 compounds. The equilibrium synthesis of the set of phases was performed inside positive electrodes (PE) of the electrochemical cells: (-)Graphite ||LE|| Fast Ag+ conducting solid-electrolyte ||R[Ag+]||PE|| Graphite(+), where LE is the left (negative) electrode, and R[Ag+] is the buffer region for the diffusion of Ag+ ions into the PE. From the observed results, thermodynamic quantities of AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 were experimentally determined for the first time. The reliability of the division of the Ag2Te-FeTe2-F1.12Te-Ag2Te and Ag8GeTe6-GeTe-FeTe2-AgFeTe2-Ag8GeTe6 phase regions was confirmed by the calculated thermodynamic quantities of AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 in equilibrium with phases in the adjacent phase regions. Particularly, the calculated Gibbs energies of Ag2FeGeTe4 in two different adjacent 4-phase regions are consistent, which also indicates that it has stoichiometric composition.
Description
Funding: This research was supported by the national projects of the Ministry of Education and Science of Ukraine: “Synthesis, physico-chemical and thermodynamic properties of nanosized and nanostructured materials for electrochemical systems” (No. 0120U102184). This work was partly supported by the Academy of Finland project (Decision number 311537), as part of the activities of the Johan Gadolin Process Chemistry Centre at Åbo Akademi University
Keywords
silver-based compounds, thermoelectric materials, phase equilibria, thermodynamic properties, Gibbs energy, EMF method
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Citation
Moroz, M, Tesfaye, F, Demchenko, P, Prokhorenko, M, Yarema, N, Lindberg, D, Reshetnyak, O & Hupa, L 2021, ' The Equilibrium Phase Formation and Thermodynamic Properties of Functional Tellurides in the Ag-Fe-Ge-Te System ', Energies, vol. 14, no. 5, 1314 . https://doi.org/10.3390/en14051314