Dawahre Lamia, Lu Ruiming, Djieutedjeu Honore, Lopez Juan, Bailey Trevor P, Buchanan Brandon, Yin Zhixiong, Uher Ctirad, Poudeu Pierre F P
Laboratory for Emerging Energy and Electronic Materials (LE3M), Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States.
ACS Appl Mater Interfaces. 2020 Oct 7;12(40):44991-44997. doi: 10.1021/acsami.0c12938. Epub 2020 Sep 28.
Designing crystalline solids in which intrinsically and extremely low lattice thermal conductivity mainly arises from their unique bonding nature rather than structure complexity and/or atomic disorder could promote thermal energy manipulation and utilization for applications ranging from thermoelectric energy conversion to thermal barrier coatings. Here, we report an extremely low lattice thermal conductivity of ∼0.34 W m K at 300 K in the new complex sulfosalt MnPbSbS. We attribute the ultralow lattice thermal conductivity to a synergistic combination of scattering mechanisms involving (1) strong bond anharmonicity in various structural building units, owing to the presence of stereoactive lone-electron-pair (LEP) micelles and (2) phonon scattering at the interfaces between building units of increasing size and complexity. Remarkably, low-temperature heat capacity measurement revealed a value of 0.206 J g K at > 300 K, which is 22% lower than the Dulong-Petit value (0.274 J g K). Further analysis of the data and sound velocity ( = 1834 m s) measurement yielded Debye temperature values of 161 and 187 K, respectively. The resulting Grüneisen parameter, γ = 1.65, further supports strong bond anharmonicity as the dominant mechanism responsible for the observed extremely low lattice thermal conductivity.
设计晶体固体，使其本征且极低的晶格热导率主要源于其独特的键合性质，而非结构复杂性和/或原子无序性，这有助于促进热能的操控和利用，应用范围涵盖从热电能量转换到热障涂层等领域。在此，我们报道了新型复合硫盐MnPbSbS在300 K时具有约0.34 W m⁻¹ K⁻¹的极低晶格热导率。我们将这种超低晶格热导率归因于多种散射机制的协同作用，这些机制包括：（1）由于存在立体活性孤对电子（LEP）胶束，各种结构单元中存在强烈的键非谐性；（2）在尺寸和复杂性不断增加的结构单元之间的界面处发生声子散射。值得注意的是，低温热容测量显示在高于300 K时的值为0.206 J g⁻¹ K⁻¹，比杜隆 - 珀蒂值（0.274 J g⁻¹ K⁻¹）低22%。对数据的进一步分析和声速（ = 1834 m s⁻¹）测量分别得出德拜温度值为161 K和187 K。由此得到的格林艾森参数γ = 1.65，进一步支持了强键非谐性是导致观察到的极低晶格热导率的主要机制。
