Archive / Volume LXXVIII 2025

Vitaliia SEMENIUK, Orysia BEREZNIUK, Lyubomyr GULAY, Ludmyla PISKACH

Lesya Ukrainka Volyn National University, Voli Ave. 13, 43025 Lutsk, Ukraine
e-mail: bereznuk.orysia@vnu.edu.ua

DOI:

THE AgC^IIIS₂ – Ag₈D^IVS₆ SECTIONS OF THE Ag₂S – C^III₂S₃ – D^IVS₂ SYSTEMS (C^III – Sb, Bi; D^IV – Ge, Sn)

Vertical sections of the phase diagrams of the quasi-binary systems AgSbS2–Ag8GeS6, AgBiS2–Ag8GeS6, and AgBiS2–Ag8SnS6 were investigated, which are triangulating in the quasi-ternary systems Ag2S–Sb(Bi)2S3–Ge(Sn)S2. The samples were synthesized from high-purity elements (at least 99.99 wt.%) by co-melting in evacuated quartz ampoules at 1170 K and annealing for 500 hours at 500 K or 570 K. Analysis of the phase composition and thermal stability utilized a set of experimental methods such as X-ray diffraction, differential thermal analysis, microstructure analysis, and scanning electron microscopy (SEM).
It was first established that a new quaternary thiol-compound of the Ag11Sb3GeS12 composition which is analogous to the Ag11Sb3SnS12 compound is formed in the AgSbS2 –Ag8GeS6 system at a component ratio of 3:1. It melts congruently at 1047 K and has a polymorphous transition at 527 K. Its formation was confirmed by the results of X-ray structure analysis, and the surface morphology was studied by SEM. It was established that this phase is stable in a wide temperature range limited by two eutectic reactions at 780 K and 997 K, respectively. The structural behavior of Ag8GeS6 is characterized by its polymorphism, depending on the cooling regime, it crystallizes in either cubic modification with S.G. F-43m (HT) or orthorhombic structure with S.G. Pna21 (LT). Vertical section of the AgBiS2–Ag8GeS6 system belongs to the eutectic type L ↔ β′ + γ′, where β′ and γ′ are solid solution ranges of AgBiS2 and HT-Ag8GeS6. The eutectic point was established at 970 K and a composition of 25 mol. % Ag8GeS6. Additionally, effects associated with polymorphous transitions of AgBiS2 and Ag8GeS6 were recorded. The tin-containing system AgBiS2–Ag8SnS6 also belongs to the eutectic type of interaction, with the characteristic reaction L ↔ AgBiS2 + Ag8SnS6. The eutectic point is 937 K and a composition of 33 mol. % Ag8SnS6. Polymorphous transitions of the end compounds were also observed.
Obtained results complement the data on phase equilibria in multicomponent chalcogenide systems, in particular those that can potentially exhibit ionic conductivity or thermoelectric properties. This opens up prospects for further study of the physico-chemical characteristics of newly formed phases and optimization of the compositions of functional materials based on them.

Keywords: quasi-binary system, eutectic, peritectic, solid solutions.

References:

1. Todorov T. K., Reuter K. B., Mitzi D. B. Next-generation solar absorbers: materials design for high-efficiency thin-film photovoltaics. Adv. Mater. 2010. Vol. 22(20). P. E156–E159. (https://doi.org/10.1002/adma.200904155).
2. Jesús Capistrán-Martinez, Nair P. C. Photoconductive thin films of AgSbS2 with cubic crystalline structure in solar cells. Phys. Status Solidi A. 2015. Vol. 212(12). P. 2869–2876. https://doi.org/10.1002/pssa.201532496. 3. Garza J. G., Shaji S., Rodriguez A. C., Roy T. K. AgSbSe2 and AgSb(S,Se)2 thin films for photovoltaic applications. Appl. Surf. Sci. 2011. Vol. 257(24). P. 10834–10838. https://doi.org/10.1016/j.apsusc.2011.07.115. 4. Voronin M. V., Osadchii E. G. Тhermodynamic properties of silver and bismuth sulfosalt minerals, pavonite (AgBi3S5) and matildite (AgBiS2) and implications for ore deposits. Econ. Geol. 2013. Vol. 108(5). P. 1203–1210. https://doi.org/10.2113/econgeo. 108.5.1203. 5. Zhou Y., Wang L., Chen S., et al. Thin-film solar cells based on AgBiS2 nanocrystals. Nat. Photon. 2015. Vol. 9(7). P. 409–415. https://doi.org/10.1038/nphoton.2015.91. 6. Lin S., Li W., Pei Y. Thermally insulative thermoelectric argyrodites. Mater. Today. 2021. Vol. 48. P. 198–213. https://doi.org/10.1016/j.mattod.2021.01.007. 7. Semkiv I. V., Ilchuk H., Pawlowski M., Kusnezh V. Ag8SnSe6 argyrodite synthesis and optical properties. Opto-Electron. Rev. 2017. Vol. 25(1). P. 37–40. https://doi.org/10.1016/ j.opelre.2017.04.002. 8. Shen X., Xia Y., Yang C. C., Zhang Z., Li S., Tung Y. H., Benton A., Zhang X., Lu X., Wang G., He J., Zhou X. High thermoelectric performance in sulfide-type argyrodites compound Ag8Sn(S1-xSex)6 enabled by ultralow lattice thermal conductivity and extended cubic phase regime. Adv. Funct. Mater. 2020. Vol. 30(21). 2000526 https://doi.org/10.1002/adfm.202000526. 9. Chen H. M., Maohua C., Adams S. Stability and ionic mobility in argyrodite-related lithium-ion solid electrolytes. Phys. Chem. Chem. Phys. 2015. Vol. 17. P. 16494–16506. https://doi.org/ 10.1039/C5CP01841B. 10. Filep M. Y., Pohodin A. I., Malakhovska T. O., Kokhan O. P., Chundak S. Yu., Kaila M. I., Skubenych K. V. Doslidzhennia elektrychnykh vlastyvostei monokrystalichnoho Ag8GeS6. Nauk. Visn. Uzhhorod. Univ., Ser. Khim. 2023. Vyp. 1(49). S. 10–14. https://doi.org/ 10.24144/2414-0260.2023.1.10-14. (in Ukrainian). 11. Applications of Chalcogenides: S, Se, and Te / ed. by G. K. Ahluwalia. Cham : Springer International Publishing, 2017. 474 p. https://doi.org/10.1007/978-3-319-41190-3. 12. Bryndzia L. T., Kleppa O. J. High-temperature reaction calorimetry of solid and liquid phases in the quasi-binary system Ag2S–Sb2S3. Geochim. Cosmochim. Acta. 1989. Vol. 52. P. 67–176. https://doi.org/10.1016/0016-7037(88)90064-6. 13. Tesfaye F., Lindberg D. Thermochemical properties of selected ternary phases in the Ag–Bi–S. J. Mater. Sci. 2016. Vol. 51. P. 5750–5759. https://doi.org/10.1007/s10853-016-9877-8. 14. Walenta K. Cuboargyrit, ein neues Silbermineral aus dem Schwarzwald. Lapis. 1998. Vol. 23(11). P. 21–23. 15. Smith J. V., Pluth J. J., Han S. Crystal structure refinement of miargyrite AgSbS2. Mineral. Mag. 1997. Vol. 61. P. 671–675. https://doi.org/10.1180/minmag.1997.061.408.05. 16. Gorochov O. Les composés Ag8MX6 (M = Si, Ge, Sn et X = S, Se, Te). Bull. Soc. Chim. Fr. 1968. Vol. 6. P. 2263–2275. 17. Eulenberger G. Die Kristallstruktur der Tieftemperaturmodifikation von Ag8GeS6. Monatsh. Chem. 1977. Vol. 108. P. 901–913. https://doi.org/10.1007/BF00898056. 18. Piskach L. V., Parasyuk O. V., Olekseyuk I. D. Interaction of argyrodite family compounds with the chalcogenides of II-b elements. J. Alloys Compd. 2006. Vol. 421(1–2). P. 98–104. https://doi.org/10.1016/j.jallcom.2005.11.056. 19. Berezniuk O. P., Alrikik M., Kohut Yu. M., Piskach L. V. Phase equilibria in the Cu(Ag)2S–SnS2–Sb2S3 systems. Probl. Chem. Sustain. Dev. 2022. No. 4. P. 17–30. (in Ukrainian). https://doi.org/10.32782/pcsd-2022-4-2. 20. Berezniuk O. P., Kogut Y. M., Gulay L. D., Piskach L. V. Phase equilibria in the Ag2S–Sb2S3–SnS2 system and the novel quaternary chalcogenide Ag11Sb3SnS12. J. Phase Equilib. Diffus. 2024. Vol. 45. P. 723–731. https://doi.org/10.1007/s11669-024-01126-7.