Qiu Junhao, Luo Tingting, Yan Yonggao, Xia Fanjie, Yao Lei, Tan Xiaoming, Yang Dongwang, Tan Gangjian, Su Xianli, Wu Jinsong, Tang Xinfeng
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, Hubei 430070, China.
Nanostructure Research Center, Wuhan University of Technology, Wuhan, Hubei 430070, China.
ACS Appl Mater Interfaces. 2021 Dec 15;13(49):58974-58981. doi: 10.1021/acsami.1c19172. Epub 2021 Dec 2.
BiTe-based materials are dominating thermoelectrics for almost all of the room-temperature applications. To meet the future demands, both their thermoelectric (TE) and mechanical properties need to be further improved, which are the requisite for efficient TE modules applied in areas such as reliable micro-cooling. The conventional zone melting (ZM) and powder metallurgy (PM) methods fall short in preparing BiTe-based alloys, which have both a highly textured structure for high TE properties and a fine-grained microstructure for high mechanical properties. Herein, a mechanical exfoliation combined with spark plasma sintering (ME-SPS) method is developed to prepare BiSbTe with highly improved mechanical properties (correlated mainly to the dislocation networks), as well as significantly improved thermoelectric properties (correlated mainly to the texture structure). In the method, both the dislocation density and the orientation factor () can be tuned by the sintering pressure. At a sintering pressure of 20 MPa, an exceptional of up to 0.8 is retained, leading to an excellent power factor of 4.8 mW m K that is much higher than that of the PM polycrystalline. Meanwhile, the method can readily induce high-density dislocations (up to ∼10 cm), improving the mechanical properties and reducing the lattice thermal conductivity as compared to the ZM ingot. In the exfoliated and then sintered (20 MPa) sample, the figure-of-merit ZT = 1.2 (at 350 K), which has increased by about ∼20%, and the compressive strength has also increased by ∼20%, compared to those of the ZM ingot, respectively. These results demonstrate that the ME-SPS method is highly effective in preparing high-performance BiTe-based alloys, which are critical for TE modules in commercial applications at near-room temperature.
基于BiTe的材料在几乎所有室温应用的热电材料中占据主导地位。为满足未来需求，其热电（TE）性能和机械性能都需要进一步提高，这是应用于可靠微冷却等领域的高效TE模块的必要条件。传统的区熔（ZM）和粉末冶金（PM）方法在制备基于BiTe的合金时存在不足，这类合金需要同时具备用于高TE性能的高度织构化结构和用于高机械性能的细晶微观结构。在此，开发了一种机械剥离结合放电等离子烧结（ME-SPS）的方法来制备BiSbTe，其机械性能（主要与位错网络相关）得到了显著改善，热电性能（主要与织构结构相关）也得到了显著提高。在该方法中，位错密度和取向因子（）都可以通过烧结压力进行调节。在20 MPa的烧结压力下，保留了高达0.8的优异取向因子，导致了4.8 mW m K的优异功率因子，远高于PM多晶的功率因子。同时，与ZM铸锭相比，该方法能够轻易诱导高密度位错（高达~10 cm），改善机械性能并降低晶格热导率。在经过剥离然后烧结（20 MPa）的样品中，优值ZT = 1.2（在350 K时），与ZM铸锭相比分别提高了约20%，抗压强度也提高了约20%。这些结果表明，ME-SPS方法在制备高性能基于BiTe的合金方面非常有效，这对于近室温商业应用中的TE模块至关重要。
