Strong Anharmonicity at the Origin of Anomalous Thermal Conductivity in Double Perovskite Cs2NaYbCl6

Autor: Antonio Cappai, Claudio Melis, Daniela Marongiu, Francesco Quochi, Michele Saba, Francesco Congiu, Yihui He, Tyler J. Slade, Mercouri G. Kanatzidis, Luciano Colombo
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Advanced Science, Vol 11, Iss 9, Pp n/a-n/a (2024)
Druh dokumentu: article
ISSN: 2198-3844
DOI: 10.1002/advs.202305861
Popis: Abstract Anomalous thermal transport of Cs2NaYbCl6 double‐halide perovskite above room temperature is reported and rationalized. Calculations of phonon dispersion relations and scattering rates up to the fourth order in lattice anharmonicity have been conducted to determine their effective dependence on temperature. These findings show that specific phonon group velocities and lifetimes increase if the temperature is raised above 500 K. This, in combination with anharmonicity, provides the microscopic mechanism responsible for the increase in lattice thermal conductivity at high temperatures, contrary to the predictions of phonon transport theories based on solely cubic anharmonicity. The model accurately and quantitatively reproduces the experimental thermal conductivity data as a function of temperature.
Databáze: Directory of Open Access Journals
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