Ultralow thermal conductivity from transverse acoustic phonon suppression in distorted crystalline α-MgAgSb.,Nature Communications

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Ultralow thermal conductivity from transverse acoustic phonon suppression in distorted crystalline α-MgAgSb.
Nature Communications ( IF 14.7 ) Pub Date : 2020-02-18 , DOI: 10.1038/s41467-020-14772-5
Xiyang Li _{1,

2,

3,

4} , Peng-Fei Liu ₅ , Enyue Zhao _{1,

4} , Zhigang Zhang ₂ , Tatiana Guidi ₆ , Manh Duc Le ₆ , Maxim Avdeev ₇ , Kazutaka Ikeda ₈ , Toshiya Otomo ₈ , Maiko Kofu ₉ , Kenji Nakajima ₉ , Jie Chen ₅ , Lunhua He _{1,

5} , Yang Ren ₁₀ , Xun-Li Wang ₃ , Bao-Tian Wang ₅ , Zhifeng Ren ₁₁ , Huaizhou Zhao ₁ , Fangwei Wang _{1,

2,

4}

Affiliation

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Songshan Lake Materials Laboratory, Dongguan, 523808, China.
Department of Physics, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong, China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 101408, China.
Spallation Neutron Source Science Center, Dongguan, 523803, China.
ISIS facility, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, Oxfordshire, UK.
Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia.
Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, 305-0801, Japan.
Japan Proton Accelerator Research Complex, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan.
X-ray Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA.
Department of Physics and TcSUH, University of Houston, Houston, Texas, 77204, USA.

Low thermal conductivity is favorable for preserving the temperature gradient between the two ends of a thermoelectric material, in order to ensure continuous electron current generation. In high-performance thermoelectric materials, there are two main low thermal conductivity mechanisms: the phonon anharmonic in PbTe and SnSe, and phonon scattering resulting from the dynamic disorder in AgCrSe2 and CuCrSe2, which have been successfully revealed by inelastic neutron scattering. Using neutron scattering and ab initio calculations, we report here a mechanism of static local structure distortion combined with phonon-anharmonic-induced ultralow lattice thermal conductivity in α-MgAgSb. Since the transverse acoustic phonons are almost fully scattered by the compound's intrinsic distorted rocksalt sublattice, the heat is mainly transported by the longitudinal acoustic phonons. The ultralow thermal conductivity in α-MgAgSb is attributed to its atomic dynamics being altered by the structure distortion, which presents a possible microscopic route to enhance the performance of similar thermoelectric materials.

中文翻译：

扭曲晶体 α-MgAgSb 中横向声子抑制产生的超低导热率。

低导热率有利于保持热电材料两端之间的温度梯度，以确保连续的电子电流产生。在高性能热电材料中，存在两种主要的低热导率机制：PbTe和SnSe中的声子非简谐，以及AgCrSe2和CuCrSe2中动态无序引起的声子散射，这已被非弹性中子散射成功揭示。利用中子散射和从头计算，我们在此报告了 α-MgAgSb 中静态局域结构畸变与声子非简谐引起的超低晶格热导率相结合的机制。由于横向声子几乎完全被化合物固有的扭曲岩盐亚晶格散射，因此热量主要由纵向声子传输。 α-MgAgSb 的超低导热率归因于其原子动力学因结构畸变而改变，这为增强类似热电材料的性能提供了可能的微观途径。

更新日期：2020-02-18

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