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

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Strong Anharmonicity at the Origin of Anomalous Thermal Conductivity in Double Perovskite Cs2NaYbCl6
Advanced Science ( IF 14.3 ) Pub Date : 2023-12-18 , DOI: 10.1002/advs.202305861
Antonio Cappai ₁ , Claudio Melis ₁ , Daniela Marongiu ₁ , Francesco Quochi ₁ , Michele Saba ₁ , Francesco Congiu ₁ , Yihui He ₂ , Tyler J Slade ₂ , Mercouri G Kanatzidis ₂ , Luciano Colombo ₁

Affiliation

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.

中文翻译：

双钙钛矿 Cs2NaYbCl6 反常热导率起源的强非谐性

报道并合理化了 Cs ₂ NaYbCl ₆双卤化物钙钛矿在室温以上的反常热传输。计算了声子色散关系和高达四阶晶格非谐性的散射率，以确定它们对温度的有效依赖性。这些发现表明，如果温度升高到 500 K 以上，特定声子群速度和寿命会增加。这与非谐性相结合，提供了高温下晶格热导率增加的微观机制，这与声子输运的预测相反仅基于三次非调和性的理论。该模型准确、定量地再现了实验热导率数据作为温度的函数。

更新日期：2023-12-18

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