Research Article

Phase behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ systems and new cubic argyrodyte phases with variable composition

Volume: 2026 Number: 2 September 11, 2026

Phase behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ systems and new cubic argyrodyte phases with variable composition

Abstract

Argyrodite-family compounds and their derivative phases are environmentally friendly functional materials with a wide range of valuable properties, including thermoelectric, photoelectric, and optical properties, as well as high ionic conductivity arising from the high mobility of Cu⁺ and Ag⁺ ions. In this study, phase equilibria in the Cu₈SiS₆–Ag₈SiS₆ and Cu₈SiSe₆–Ag₈SiSe₆ argyrodite systems were investigated using differential thermal analysis, X-ray diffraction, and microhardness measurements, and the corresponding temperature–composition (T–x) phase diagrams were constructed. It was established that both systems exhibit quasi-binary behavior and are characterized by the formation of continuous solid solutions (δ-phase) between the high-temperature modifications of the parent compounds, as well as extensive solid-solution regions based on their low-temperature modifications. The formation of these solid solutions is accompanied by a systematic decrease in the temperatures of polymorphic transitions of the parent phases, thereby stabilizing the δ-phase at room temperature. Furthermore, it was determined that, at room temperature, the homogeneity range of the δ-phase spans 10–50 mol% Ag₈SiS₆ for the sulfide system and 10–85 mol% Ag₈SiSe₆ for the selenide system. The lattice parameters of the synthesized solid solutions were determined from X-ray diffraction data, and showed a linear dependence on composition consistent with Vegard’s law. The formation of continuous cubic solid solutions is accompanied by an increase in microhardness due to solid-solution strengthening.

Keywords

References

  1. 1. Parashchuk T, Cherniushok O, Wiendlocha B, Tobola J, Cardoso‐Gil R, Snyder GJ, et al. High thermoelectric performance in low‐cost Cu8SiSxSe6‐x argyrodite. Adv Funct Mater. 2025 Aug 24;35(34):2502163. Available from: .
  2. 2. Yang Y, Yuan L, Chen Z, Guo W, Zheng Y, Ming H, et al. The new cubic argyrodites: Ag4M0.5S2Te (M = Sn and Ge) with ultralow thermal conductivity. Adv Funct Mater. 2025 Sep 14;35(37):2501431. Available from: .
  3. 3. Dandena BD, Tsai DS, Wu SH, Su WN, Hwang BJ. Review of interface issues in Li–argyrodite-based solid-state Li–metal batteries. EES Batter. 2025;1(4):692–743. Available from: .
  4. 4. Ghata A, Eckert PL, Böger T, Garg P, Zeier WG. Influence of Cu+ substitution on the structural, ionic, and thermal transport properties of Ag8–xCuxGeS6 argyrodites. Chem Mater. 2025 Sep 9;37(17):6900–11. Available from: .
  5. 5. Ghata A, Bernges T, Maus O, Wankmiller B, Naik AA, Bustamante J, et al. Exploring the thermal and ionic transport of Cu+ conducting argyrodite Cu7PSe6. Adv Energy Mater. 2024 Dec 12;14(46):2402039. Available from: .
  6. 6. Shen X, Koza MM, Tung Y, Ouyang N, Yang C, Wang C, et al. Soft Phonon Mode Triggering Fast Ag Diffusion in Superionic Argyrodite Ag8GeSe6. Small. 2023 Dec 18;19(49):2305048. Available from: .
  7. 7. Kang T, Li C, Zhang X, Nakamura Y, Tseng J chi, Manjo T, et al. Local symmetry breaking induced superionic conductivity in argyrodites. J Am Chem Soc. 2026 Feb 18;148(6):6158–66. Available from: .
  8. 8. Ren Q, Gupta MK, Jin M, Ding J, Wu J, Chen Z, et al. Extreme phonon anharmonicity underpins superionic diffusion and ultralow thermal conductivity in argyrodite Ag8SnSe6. Nat Mater. 2023 Aug 18;22(8):999–1006. Available from: .

Details

Primary Language

English

Subjects

Inorganic Materials

Journal Section

Research Article

Publication Date

September 11, 2026

Submission Date

May 1, 2026

Acceptance Date

July 28, 2026

Published in Issue

Year 2026 Volume: 2026 Number: 2

APA
Poladova, A., Namazov, J., Mashadiyeva, L., Yusibov, Y., & Babanly, M. (2026). Phase behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ systems and new cubic argyrodyte phases with variable composition. Journal of the Turkish Chemical Society Section A: Chemistry, 2026(2), 1-9. https://doi.org/10.18596/jotcsa.1941935
AMA
1.Poladova A, Namazov J, Mashadiyeva L, Yusibov Y, Babanly M. Phase behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ systems and new cubic argyrodyte phases with variable composition. JOTCSA. 2026;2026(2):1-9. doi:10.18596/jotcsa.1941935
Chicago
Poladova, Albina, Joshgun Namazov, Leyla Mashadiyeva, Yusif Yusibov, and Mahammad Babanly. 2026. “Phase Behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ Systems and New Cubic Argyrodyte Phases With Variable Composition”. Journal of the Turkish Chemical Society Section A: Chemistry 2026 (2): 1-9. https://doi.org/10.18596/jotcsa.1941935.
EndNote
Poladova A, Namazov J, Mashadiyeva L, Yusibov Y, Babanly M (September 1, 2026) Phase behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ systems and new cubic argyrodyte phases with variable composition. Journal of the Turkish Chemical Society Section A: Chemistry 2026 2 1–9.
IEEE
[1]A. Poladova, J. Namazov, L. Mashadiyeva, Y. Yusibov, and M. Babanly, “Phase behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ systems and new cubic argyrodyte phases with variable composition”, JOTCSA, vol. 2026, no. 2, pp. 1–9, Sept. 2026, doi: 10.18596/jotcsa.1941935.
ISNAD
Poladova, Albina - Namazov, Joshgun - Mashadiyeva, Leyla - Yusibov, Yusif - Babanly, Mahammad. “Phase Behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ Systems and New Cubic Argyrodyte Phases With Variable Composition”. Journal of the Turkish Chemical Society Section A: Chemistry 2026/2 (September 1, 2026): 1-9. https://doi.org/10.18596/jotcsa.1941935.
JAMA
1.Poladova A, Namazov J, Mashadiyeva L, Yusibov Y, Babanly M. Phase behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ systems and new cubic argyrodyte phases with variable composition. JOTCSA. 2026;2026:1–9.
MLA
Poladova, Albina, et al. “Phase Behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ Systems and New Cubic Argyrodyte Phases With Variable Composition”. Journal of the Turkish Chemical Society Section A: Chemistry, vol. 2026, no. 2, Sept. 2026, pp. 1-9, doi:10.18596/jotcsa.1941935.
Vancouver
1.Albina Poladova, Joshgun Namazov, Leyla Mashadiyeva, Yusif Yusibov, Mahammad Babanly. Phase behavior in Cu₈SiS₆-Ag₈SiS₆ and Cu₈SiSe₆-Ag₈SiSe₆ systems and new cubic argyrodyte phases with variable composition. JOTCSA. 2026 Sep. 1;2026(2):1-9. doi:10.18596/jotcsa.1941935