Fundamental understanding of thermal transport in compounds with ultra-low thermal conductivity remains challenging, primarily due to the limitations of conventional lattice dynamics and heat transport models. In this study, we investigate the thermal transport in quasi-one-dimensional (1D) copper halide CsCu2I3 by employing a combination of first principles-based self-consistent phonon calculations and a dual-channel thermal transport model. Our results show that the 0-K unstable soft modes, primarily dominated by Cs and I atoms in CsCu2I3, can be an-harmonically stabilized at ~ 75 K. Furthermore, we predict an ultra-low thermal conductivity of 0.362 Wm^(-1) K^(-1) along the chain axis and 0.201 Wm^(-1) K^(-1) along cross chain direction in CsCu2I3 at 300 K. Importantly, we find that an unexpected anomalous trend of increasing cross-chain thermal conductivity with increasing temperature for CsCu2I3, following a temperature dependence of ~T 0.106, which is atypical for a single crystal and classified as an abnormal glass-like behavior. The peculiar temperature-dependent behavior of thermal conductivity is elucidated by the dominant wave-like tunnelling of phonons in thermal transport of CsCu2I3 along cross-chain direction. In contrast, particle-like phonon propagation primarily contributes to the chain-axis thermal conductivity across the entire temperature range of 300-700 K. The sharp difference in the dominant thermal transport channels between the two crystallographic directions can be attributed to the unique chain-like quasi-1D structure of CsCu2I3. Our study not only illustrates the microscopic mechanisms of thermal transport in CsCu2I3 but also paves the way for searching for and designing materials with ultra-low thermal conductivity.
Multimodal and Multiscale Interrogation of a Mechanically Tough Glass Forming Copper-Based Metal-Organic Framework
University of Oxford（牛津大学）；Technische Universität Dortmund（多特蒙德工业大学）；University of Vienna（维也纳大学）；Science and Technology Facility Council, UKRI（英国研究与创新署科学技术设施委员会）；Diamond Light Source（钻石光源）
Accelerated Discovery of Crystalline Materials with Record Ultralow Lattice Thermal Conductivity via a Universal Descriptor
Northwestern Polytechnical University（西北工业大学）；CRISMAT, CNRS, Normandie Univ, ENSICAEN, UNICAEN（诺曼底大学，卡昂国立高等工程学院，法国国家科学研究中心材料研究化学实验室）；Thayer School of Engineering, Dartmouth College（达特茅斯学院塔克工程学院）；Institute Laue Langevin（朗之万研究所）；FZU - Institute of Physics of the Czech Academy of Sciences（捷克科学院物理研究所）；ShanghaiTech Laboratory for Topological Physics & School of Physical Science and Technology, ShanghaiTech University（上海科技大学物理科学与技术学院拓扑物理实验室）；Université de Lorraine, CNRS, IJL（洛林大学，法国国家科学研究中心，界面与层析实验室）
kALDo 2.0: Scalable Thermal Transport from First Principles and Machine Learning Potentials
University of California Davis（加州大学戴维斯分校）；PSI Center for Scientific Computing Theory and Data（瑞士保罗谢勒研究所科学计算理论与数据中心）；Massachusetts Institute of Technology（麻省理工学院）；National Centre for Computational Design and Discovery of Novel Materials (MARVEL)（国家新材料计算设计与发现中心（MARVEL））
