Layered RbLnGeS4 (ln = Ce, Pr, Nd, Sm, Gd): crystal structures, Rb-site disorder–order transition, and structure–property correlations

Layered RbLnGeS4 (ln = Ce, Pr, Nd, Sm, Gd): crystal structures, Rb-site disorder–order transition, and structure–property correlations Full article

Journal

Journal of Solid State Chemistry
ISSN: 0022-4596 , E-ISSN: 1095-726X

Output data

Year: 2026, Volume: 363, Article number : 126219, Pages count : 8 DOI: 10.1016/j.jssc.2026.126219

Tags

Rare-earth elements, Thiogermanates, Rubidium, Raman spectroscopy, Diffuse reflectance spectroscopy, Optical band gap, Sm3+ photoluminescence, Non-centrosymmetric sulfides, Order–disorder transition

Authors

Sapov Alexander A. ^1,2 , Tarasenko Maria S. ¹ , Kuratieva Natalia V. ¹ , Syrokvashin Mikhail M. ^1,3 , Ryadun Alexey A. ¹ , Troitskii Dmitry Y. ¹ , Yushina Irina V. ¹ , Naumov Nikolay G. ¹

Affiliations

1	Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences (NIIC SB RAS), 3 Acad. Lavrentiev Ave., Novosibirsk 630090, Russian Federation
2	Novosibirsk State University, 1 Pirogova Str., Novosibirsk 630090, Russian Federation
3	Siberian Transport University, Dusi Kovalchuk str. 191, 630049 Novosibirsk, Russia

Funding (1)

FWUZ-2025-0002

Rare-earth thiogermanates built from isolated {GeS4} tetrahedra are attractive as optical host lattices, yet rubidium members remain insufficiently explored. Here we report the synthesis of the new members of the RbLnGeS4 series (Ln = Ce, Pr, Nd, Sm, Gd) by a high-temperature reactive flux route and their comprehensive structural and spectroscopic characterization. All compounds crystallize in the non-centrosymmetric orthorhombic space group P212121 and feature anionic [LnGeS4]− layers separated by interlayer Rb+ cations. Single-crystal X-ray diffraction reveals a split Rb position at room temperature, whereas low-temperature data together with DSC measurements indicate suppression of the rubidium positional disorder upon cooling, consistent with a kinetically limited order–disorder process. Raman spectra are dominated by modes of isolated {GeS4} tetrahedra and show systematic Ln–S-related shifts across the series. Diffuse reflectance spectra of representative compounds RbLnGeS4 (Ln = Pr, Gd) yield optical band gaps of ≥3.3 eV. In addition, Sm3+-doped RbGdGeS4 exhibits red f–f emission consistent with a low-symmetry Sm3+ environment in this host lattice.

Sapov A.A. , Tarasenko M.S. , Kuratieva N.V. , Syrokvashin M.M. , Ryadun A.A. , Troitskii D.Y. , Yushina I.V. , Naumov N.G.
Layered RbLnGeS4 (ln = Ce, Pr, Nd, Sm, Gd): crystal structures, Rb-site disorder–order transition, and structure–property correlations
Journal of Solid State Chemistry. 2026. V.363. 126219 :1-8. DOI: 10.1016/j.jssc.2026.126219 WOS Scopus

Submitted:	May 26, 2026
Accepted:	Jul 11, 2026
Published online:	Jul 20, 2026
Published print:	Nov 2, 2026

≡ Web of science:	WOS:001834831000001
≡ Scopus:	2-s2.0-105045287824