Elucidating the thermal properties and anomalous transport in the 18R polytype of SnSe2

Published

May 30, 2025

Author(s)

Oluwagbemiga Ojo, Wilarachchige D. C. B. Gunatilleke, Winnie Wong-Ng, Tieyan Chang, Yu-Sheng Chen, Joshua Martin, Adam Biacchi, George Nolas

Abstract

The 18R polytype of SnSe2 possesses unique structural features that can directly impact the transport properties and potential applications of interest; however, a comprehensive understanding of the intrinsic physical properties is lacking. We grew large crystals in order to investigate the thermal and electrical properties of this SnSe2 polytype and reveal the provenance of the anomalous electronic transport this material possesses. High-resolution single-crystal synchrotron, as well as powder X-ray diffraction on crushed crystals, were employed elucidating the long-period stacking sequence and octahedral layering along the c-axis separated by weak van der Waals bonds forming the rhombohedral lattice structure. Temperature-dependent Hall, resistivity, and Seebeck coefficient measurements were employed in investigating the atypical electrical transport this polytype possesses, which has a 1.1 eV indirect band gap as revealed from our optical spectroscopy investigations. Analyses and modelling of the temperature-dependent thermal properties revealed a low Debye temperature and average speed of sound, with minimal lattice anharmonicity resulting in relatively high thermal conductivity. Our findings will also aid research on other materials with similar layered structure types in exploring their suitability for technological applications.

Citation

Acta Materialia

Volume

295

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.actamat.2025.121190

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Keywords

Chalcogenides, layered materials, electrical transport, thermal properties

Citation

Ojo, O. , Gunatilleke, W. , Wong-Ng, W. , Chang, T. , Chen, Y. , Martin, J. , Biacchi, A. and Nolas, G. (2025), Elucidating the thermal properties and anomalous transport in the 18R polytype of SnSe2, Acta Materialia, [online], https://doi.org/10.1016/j.actamat.2025.121190, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959508 (Accessed June 15, 2025)