Distinct anharmonic characteristics of phonon-driven lattice thermal conductivity and thermal expansion in bulk MoSe<inf>2</inf> and WSe<inf>2</inf>

TitleDistinct anharmonic characteristics of phonon-driven lattice thermal conductivity and thermal expansion in bulk MoSe2 and WSe2
Publication TypeJournal Article
Year of Publication2023
AuthorsMK Gupta, S Kumar, R Mittal, SK Mishra, S Rols, O Delaire, A Thamizhavel, PU Sastry, and SL Chaplot
JournalJournal of Materials Chemistry A
Volume11
Issue40
Start Page21864
Pagination21864 - 21873
Date Published09/2023
Abstract

Using inelastic neutron scattering and X-ray diffraction measurements, together with ab initio and machine-learning molecular dynamics simulations, we bring out the distinct nature of anharmonicity in the phonon spectra of MoSe2 and WSe2 relevant to thermal transport and thermal expansion behaviour. We show that the perturbation method, including 4th-order force constants, is insufficient to capture the temperature-dependent explicit anharmonicity. The Green-Kubo method captures the explicit anharmonicity and reproduces the thermal conductivity (κl) with high fidelity. Our mode-resolved calculation reveals that the major contribution (∼90%) to κl is attributed to a small explicit anharmonicity of low-energy phonons. In contrast, these modes exhibit large positive Grüneisen parameters (implicit anharmonicity), causing the large thermal expansion of the material.

DOI10.1039/d3ta03830k
Short TitleJournal of Materials Chemistry A