High Thermoelectric Performance in SnTe Nanocomposites with All-Scale Hierarchical Structures
High Thermoelectric Performance in SnTe Nanocomposites with All-Scale Hierarchical Structures
复制标题
具有全尺度分级结构的 SnTe 纳米复合材料的高热电性能
DOI：
10.1021/acsami.0c03349
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发表时间：
2020-05-20
影响因子：
9.5
通讯作者：
Yan, Haixue
中科院分区：
文献类型：
--
作者：
Jiang, Qinghui;Hu, Huishan;Yan, Haixue
SnTe作为一种环境友好的热电材料已经引起了相当大的关注。热电优值ZT值与可以使用纳米结构的制造成功实现的低热导率有关。然而，SnTe纳米结构复合材料的实际实现往往受到反应时间长、产率低和纳米颗粒聚集的限制。本文采用Cu 2Se与SnTe之间的简单取代反应制备了具有独特的全尺度分级结构的Cu 1. 75 Te-SnTe纳米复合材料。在原子水平上，通过Cu 2Se与SnTe的反应将取代Se-Te引入晶格，在纳米水平上，在SnTe的晶界处均匀分布着平均晶粒尺寸小于1 μ m的尺寸为10 nm的Cu 1.75Te纳米夹杂物;在介观水平上，这些SnTe颗粒堆积成较大的颗粒（10-20 μ m），其进一步被主要尺寸为1-2 μ m的Cu 1.75Te颗粒包围。这些分级结构，加上额外的SnTe堆垛层错，可以有效地散射不同波长的声子，以降低晶格热导率。在873 K时，Cu_（1.75）Te摩尔含量为0.057的SnTe纳米复合材料的热导率为0.49 W·m（-1）·K（-1），比纯SnTe的热导率降低了40%。通过使用相同的方法散射声子在整个集成的长度尺度，ZT值为1.02（类似于80%的增强，与原始的SnTe相比）实现在873 K的SnTe纳米复合材料的样品与0.034 Cu1.75Te摩尔含量。ZT值的大幅增加突出了多尺度分层结构在控制声子散射方面的作用，为实现更高性能的热电块体材料提供了一种可行的替代方案。
SnTe has attracted considerable attention as an environmentally friendly thermoelectric material. The thermoelectric figure of merit ZT value is related to low thermal conductivity that can be successfully realized using fabrication of nanostructures. However, the practical realization of SnTe nanostructured composites is often limited by long reaction time, low yield, and aggregation of nanoparticles. Herein, a simple substitution reaction between Cu2Se and SnTe was adopted to realize Cu1.75Te-SnTe nanocomposites with unique all-scale hierarchical structures. On the atomic level, the substitution Se-Te is introduced into the lattice via the reaction between Cu2Se and SnTe; on the nanoscopic level, Cu1.75Te nanoinclusions with 10 nm size are evenly distributed at the grain boundaries of SnTe with average grain size less than 1 mu m; on the mesoscopic level, these SnTe grains stack up to larger particles (10-20 mu m), which are further surrounded by Cu1.75Te grains with a predominant size of 1-2 mu m. These hierarchical structures, together with additional SnTe stacking faults, can effectively scatter phonons with different wavelengths to reduce the lattice thermal conductivity. At 873 K, a thermal conductivity value of 0.49 W.m(-1).K-1 was obtained in the SnTe nanocomposite sample with 0.057 Cu1.75Te molar content, which is 40% lower than that of the pristine SnTe. By using the same approach for scattering phonons across integrated length scales, a ZT value of 1.02 (similar to 80% enhancement, compared with that of the pristine SnTe) was achieved at 873 K for the sample of the SnTe nanocomposite with 0.034 Cu1.75Te molar content. This large increase in ZT values highlights the role of multiscale hierarchical architecture in controlling phonon scattering, offering a viable alternative to realize higher performance thermoelectric bulk materials.