非谐性
声子
材料科学
热导率
正交晶系
凝聚态物理
德拜模型
Grüneisen参数
热电效应
热电材料
软模式
软化
工作(物理)
热膨胀
热力学
电介质
晶体结构
复合材料
化学
结晶学
光电子学
物理
铁电性
作者
E. Deligöz,Hacı Özışık,Emre Bölen
标识
DOI:10.1016/j.inoche.2022.109689
摘要
We have investigated the origins of ultralow thermal conductivity behavior in Ag8XSe6 (X = Si, Ge, and Sn) argyrodites compounds in orthorhombic Pmn21 structure by exploring mechanical and lattice dynamical properties using first principles calculations. The mechanical and dynamical stability were evaluated by means of elastic constants and phonon spectra. The present soft mechanical properties indicate the low Debye temperature, sound velocity, large Grüneisen parameter, and strong anharmonicity. From the phonon dispersion, it is clear that the acoustic and low optical modes are overlapped largely. This work demonstrates that Ag8SiSe6, Ag8GeSe6, Ag8SnSe6 have ultralow thermal conductivity. They are promising potential thermoelectric materials with the softening of the transverse acoustic (TA) phonon modes caused by the heavy element (Ag).
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