Speaker
Description
Low lattice thermal conductivity is critical to thermoelectric materials and thermal barrier coatings. Combining first-principles calculations and neutron scattering experiments using CSNS@MPI as well as J-PARC@AMATERAS, we study the phonon dynamics properties of the recently synthesized low thermal conductivity material CsAg5Te3 [1]. Our results demonstrate that the liquid-like heat transfer could indeed exist in a well-ordered crystal. The low lattice thermal conductivity is mainly originated from its weak chemical bonding and strong phonon anharmonicity. Particle-like phonons and heat-carrying wave-like phonons contribute differently at different temperatures and the coupling between them leads to the nearly temperature independent behavior of lattice thermal conductivity [2]. In addition, we also study the lattice structure, chemical bonding, harmonic as well as anharmonic phonon dynamics, and lattice thermal conductivity of the tetragonal α-CsCu5Se3 by using first-principles calculations. The weak temperature dependence of the lattice thermal conductivity is carefully explained [3].
Keywords：Phonon dynamics, Dynamic structure factor, First-principles, Inelastic neutron scattering, Boltzmann transport
References:
[1] Lin H., Tan G., Wu L.M., Kanatzidis M.G., et al. Concerted rattling in CsAg5Te3 leading to ultralow thermal conductivity and high thermoelectric performance, Angew. Chem. Int. Ed., 2016, 55:11431–11436.
[2] Liu Peng-Fei, Li Xiyang, Lin Hua, Zhang Junrong, He Jiaqing, Wang Bao-Tian, et al., Strong low-energy rattling modes enabled liquid-like ultralow thermal conductivity in a well-ordered solid, National Science Review, 2025, 12, nwae216.
[3] Xie Qing-Yu, Liu Peng-Fei, Ma Jiang-Jiang, Wu Li-Ming, Zhang Kai-Wang, and Wang Bao-Tian*, Microscopic mechanisms of glasslike lattice thermal conductivity in tetragonal α-CsCu5Se3, Phys. Rev. B, 2023, 108, 014302.
