She Aixian, Zhao Yinchang, Ni Jun, Meng Sheng, Dai Zhenhong
Department of Physics, Yantai University, Yantai 264005, People's Republic of China.
Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China.
Phys Chem Chem Phys. 2023 Aug 23;25(33):22467-22476. doi: 10.1039/d3cp02194g.
The presence of rattlers in the host-guest structure has sparked great interest in the field of thermoelectrics, as it allows for the suppression of thermal transport in materials through vigorous anharmonic vibrations. This work predicts a ternary half-Heusler compound, LiAgTe, with good thermoelectric properties and high-temperature stability, which possesses a host-guest structure. Furthermore, it provides a detailed analysis of the role of rattlers in the transport process. By microscopically exploring rattlers, we have revealed that rattlers (Ag atoms), while suppressing the thermal transport properties of the host framework, provide a significant enhancement of the electronic transport capability through the provision of nearly free weakly bound electrons. Using self-consistent phonon theory combined with compressive sensing lattice dynamics method, we captured the exact lattice thermal conductivity considering quartic anharmonicity and four-phonon scattering, and obtained the electronic transport parameters through the calculation of , which includes full anisotropic acoustic deformation potential scattering, polar optical phonon scattering, and ionized impurity scattering. We systematically dissected the role of rattlers in the host-guest structure by combining methods such as electron local function, Bader charge density, and Vibration visualization. The anharmonic vibrations of rattlers enhance the temperature response of scattering, resulting in rapid deterioration of thermal transport at high temperatures. Moreover, the extended d-orbital electrons of the rattlers, together with the p-orbital electrons of the Te atom in the host framework, result in the coexistence of maximum degeneracy and high dispersion bands in the valence band, which greatly enhances the electronic transport properties.
主客体结构中“振动子”的存在引发了热电领域的极大兴趣，因为它能够通过强烈的非谐振动抑制材料中的热传输。这项工作预测了一种具有良好热电性能和高温稳定性的三元半赫斯勒化合物LiAgTe，它具有主客体结构。此外，该工作还详细分析了“振动子”在传输过程中的作用。通过微观探究“振动子”，我们发现“振动子”（Ag原子）在抑制主体框架热传输性能的同时，通过提供近自由的弱束缚电子显著增强了电子传输能力。我们使用自洽声子理论结合压缩感知晶格动力学方法，考虑四次非谐性和四声子散射精确捕捉了晶格热导率，并通过计算 获得了电子传输参数，其中包括全各向异性声学形变势散射、极性光学声子散射和电离杂质散射。我们通过结合电子局域函数、巴德电荷密度和振动可视化等方法，系统地剖析了“振动子”在主客体结构中的作用。“振动子”的非谐振动增强了散射的温度响应，导致高温下热传输迅速恶化。此外，“振动子”的扩展d轨道电子与主体框架中Te原子的p轨道电子共同作用，导致价带中出现最大简并和高色散带的共存，极大地增强了电子传输性能。
