Open Access

ARTICLE

Synthesis, Crystal Structure, Optical, and Thermal Properties of a Novel Quaternary Selenide EuErAgSe₃

Navruzbek Habibullayev^1,*, Ilya Yurev^1,2, Maxim Molokeev^1,3,4, Aleksandr Aleksandrovsky^3,5, Olga Trofimova¹, Nikita Shulaev¹, Svetlana Volkova¹, Oleg Andreev^1,6
1 University of Tyumen, Volodarskogo St., 6, Tyumen, Russia
2 Kurgan State University, Sovetskaya St., 63, Building 4, Kurgan, Russia
3 Kirensky Institute of Physics, Akademgorodok St., 50, Building 38, Krasnoyarsk, Russia
4 Far Eastern State Transport University, Seryshev St., 47, Khabarovsk, Russia
5 Siberian Federal University, Svobodny Pr., 79, Krasnoyarsk, Russia
6 Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences, Pervomaiskaya St., 91, Ekaterinburg, Russia
* Corresponding Author: Navruzbek Habibullayev. Email:

Chalcogenide Letters https://doi.org/10.32604/cl.2026.085815

Received 19 May 2026; Accepted 29 June 2026; Published online 27 July 2026

Abstract

A novel quaternary selenide, EuErAgSe₃, has been synthesized for the first time. The phase forms upon annealing in the 1120–1800 K range and retains its crystal structure upon cooling to ambient conditions. The phase was prepared by the ampoule method from EuSe and AgErSe₂ powders, followed by annealing at 1270 ± 10 K for up to 300 h. Powder X-ray diffraction revealed that EuErAgSe₃ crystallizes in the AgBiS₂ structure type (space group Fm-3m) with the lattice parameter a = 5.95322(14) Å. The microhardness of the phase is 340 ± 15 HV. The optical band gap for direct transitions is 1.78 eV, and for indirect transitions, it is 1.36 eV. The phase begins to form in the temperature range 1120–1170 K, likely due to diffusion processes, and melts incongruently at 1830 ± 30 K. The formation of EuLnAgSe₃ phases was predicted for Ln = Gd–Lu, Y and confirmed experimentally for Gd, with a = 5.9906(4) Å, and for Yb, with a = 5.9312(5) Å. In the EuLnAgSe₃ series, the unit cell parameter decreases linearly with the ionic radius of Ln³⁺.

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Keywords

Quaternary rare-earth selenides; cation-disordered cubic structure; optical band gap; incongruent melting; artificial intelligence

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