Ultralow thermal conductivity from transverse acoustic phonon suppression in distorted crystalline α-MgAgSb
Ultralow thermal conductivity from transverse acoustic phonon suppression in distorted crystalline α-MgAgSb
复制标题
扭曲晶体 α-MgAgSb 中横向声子抑制产生的超低热导率
DOI：
10.1038/s41467-020-14772-5
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发表时间：
2020-02-18
影响因子：
16.6
通讯作者：
Wang, Fangwei
中科院分区：
文献类型：
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作者：
Li, Xiyang;Liu, Peng-Fei;Wang, Fangwei
较低的热导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机制：PbTe和SnSe中的声子非谐，以及AgCrSe2和CuCrSe2中的动力学无序引起的声子散射，这两种机制已经被非弹性中子散射成功地揭示出来。利用中子散射和从头计算方法，我们报道了α-MgAgSb中声子非简谐引起的超低晶格热导率与静态局域结构扭曲相结合的机制。由于横向声学声子几乎完全被化合物的本征扭曲岩盐子晶格散射，热量主要通过纵向声学声子传输。α-MgAgSb的超低热导率是由于其原子动力学被结构扭曲所改变，这为提高类似热电材料的性能提供了一条可能的微观途径。
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 alpha-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 alpha-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.