Particlelike and wavelike behavior of phonons in Cs2AgIn𝑋6 (𝑋=Cl, Br) perovskites: How rattling vibrations and octahedral rotations govern thermal transport
发布时间：2026-07-28点击次数：
-
影响因子：3.9
-
DOI码：10.1103/23m4-vt92
-
所属单位：材料与物理学院
-
发表刊物：Physical Review B
-
刊物所在地：American Physical Society
-
项目来源：国家自然科学基金面上项目(No. 12374079, 12174017)
-
摘要：Conventional Peierls theory cannot fully capture the thermal transport in strongly anharmonic compounds (e.g., lead-free halide double perovskites) because it does not account for the significant wavelike behavior of phonons—a consequence of their inherent capability to interfere and tunnel. Here, we elucidate the mechanism behind the ultralow lattice thermal conductivity in model systems Cs2AgInCl6 and Cs2AgInBr6 through a combined evaluation of the particlelike and wavelike thermal transport channels. The rattling vibrations of Cs atoms suppress the particlelike channel through enhanced anharmonicity and promote the wavelike channel by flattening phonon branches to enhance coherence. Furthermore, the 𝑇1𝑔 rotational mode of the InX6 octahedron induces stronger quartic anharmonicity in Cs2AgInBr6 than in Cs2AgInCl6, which primarily enhances four-phonon scattering processes to further suppress the particlelike channel. In contrast, the wavelike contributions in both compounds remain comparable due to a compensating effect between the stronger coherent coupling in Cs2AgInBr6 and the larger group velocities in Cs2AgInCl6. Overall, the dominance of the wavelike channel is more pronounced in Cs2AgInBr6. Finally, the dominant wavelike contribution leads to a markedly weaker temperature dependence of the total thermal conductivity in both compounds, which is more notable in Cs2AgInBr6 with a scaling exponent of 𝑇−0.19 compared to 𝑇−0.52 in Cs2AgInCl6. Our work establishes the wavelike channel as a vital mechanism for thermal transport in lead-free halide double perovskites, providing novel insights into their fundamental thermal properties.
-
第一作者：周冉
-
论文类型：期刊论文
-
通讯作者：时洪亮,段益峰
-
学科门类：理学
-
一级学科：物理学
-
文献类型：J
-
卷号：114
-
期号：01
-
页面范围：014318
-
ISSN号：2469-9950
-
是否译文：否
-
发表时间：2026-07-28
-
收录刊物：SCI
-
发布期刊链接：https://journals.aps.org/prb/abstract/10.1103/23m4-vt92
手机版