TY - JOUR
T1 - The Equilibrium Phase Formation and Thermodynamic Properties of Functional Tellurides in the Ag-Fe-Ge-Te System
AU - Moroz, Mykola
AU - Tesfaye, Fiseha
AU - Demchenko, Pavlo
AU - Prokhorenko, Myroslava
AU - Yarema, Nataliya
AU - Lindberg, Daniel
AU - Reshetnyak, Oleksandr
AU - Hupa, Leena
N1 - 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
PY - 2021/2/28
Y1 - 2021/2/28
N2 - 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.
AB - 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.
KW - silver-based compounds
KW - thermoelectric materials
KW - phase equilibria
KW - thermodynamic properties
KW - Gibbs energy
KW - EMF method
UR - http://www.scopus.com/inward/record.url?scp=85106216250&partnerID=8YFLogxK
U2 - 10.3390/en14051314
DO - 10.3390/en14051314
M3 - Article
SN - 1996-1073
VL - 14
JO - Energies
JF - Energies
IS - 5
M1 - 1314
ER -
