Nanotwins Strengthening High Thermoelectric Performance Bismuth Antimony Telluride Alloys.
Nanotwins Strengthening High Thermoelectric Performance Bismuth Antimony Telluride Alloys.
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Nanotwins 强化高热电性能碲化铋锑合金
DOI：
10.1002/advs.202200432
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发表时间：
2022-05
期刊：
影响因子：
15.1
通讯作者：
Sui, Jiehe
中科院分区：
文献类型：
--
作者：
Qin, Haixu;Qu, Wanbo;Zhang, Yang;Zhang, Yongsheng;Liu, Zihang;Zhang, Qian;Wu, Haijun;Cai, Wei;Sui, Jiehe
Bi 2 Te 3基热电合金已在固态制冷领域实现了商业化，但其力学性能差限制了其进一步的应用。理论上已经证明纳米孪晶可以有效地强化这些合金，有时可以通过合成过程中的强烈变形来构建。然而，不明确的形成机制限制了Bi_2 Te_3基材料的孪晶界工程的可行性。在此，对一系列Bi0.4Sb1.6Te3+ δ 合金中孪晶的形成机制进行了系统的研究。结果表明，孪晶是在烧结过程中形成的退火型孪晶，对Te不足敏感，而不是形变型孪晶。Te缺陷与机械变形相结合是构建致密纳米孪晶的先决条件。通过将δ降低到-0.01以下并进行强烈变形，获得了具有高密度纳米孪晶的样品，并表现出超过250 MPa的超高抗压强度，几乎是之前报道的分级纳米结构（Bi，Sb）2 Te 3合金记录的两倍。此外，受益于抑制的本征激发，这种坚固材料的平均zT值可以在30-250 °C内达到接近1.1。这项工作为设计用于微型器件开发的高性能和机械稳定的Bi 2 Te 3基合金开辟了一条新途径。这项研究报告了仅通过纳米孪晶强化具有高热电性能的（Bi，Sb）2 Te 3的巨大进步，超高压缩强度超过250 MPa，几乎是以前在分级纳米结构（Bi，Sb）2 Te 3合金中报告的记录的两倍。它从阐明孪晶的形成机制开始，然后操纵高密度纳米孪晶以协同优化热电和机械性能。
Bi2Te3 based thermoelectric alloys have been commercialized in solid‐state refrigeration, but the poor mechanical properties restrict their further application. Nanotwins have been theoretically proven to effectively strengthen these alloys and could be sometimes constructed by strong deformation during synthesis. However, the obscure underlying formation mechanism restricts the feasibility of twin boundary engineering on Bi2Te3 based materials. Herein, thorough microstructure characterizations are employed on a series of Bi0.4Sb1.6Te3+ δ alloys to systematically investigate the twins’ formation mechanism. The results show that the twins belong to the annealing type formed in the sintering process, which is sensitive to Te deficiency, rather than the deformation one. The Te deficiency combined with mechanical deformation is prerequisite for constructing dense nanotwins. By reducing the δ below −0.01 and undergoing strong deformation, samples with a high density of nanotwins are obtained and exhibit an ultrahigh compressive strength over 250 MPa, nearly twice as strong as the previous record reported in hierarchical nanostructured (Bi, Sb)2Te3 alloy. Moreover, benefitting from the suppressed intrinsic excitation, the average zT value of this robust material could reach near 1.1 within 30–250 °C. This work opens a new pathway to design high‐performance and mechanically stable Bi2Te3 based alloys for miniature device development. This study reports a great advance in strengthening (Bi, Sb)2Te3 with high thermoelectric performance solely through nanotwins, an ultra‐high compressive strength over 250 MPa, nearly twice that of the previous record reported in hierarchical nanostructured (Bi, Sb)2Te3 alloy. It starts from clarifying the formation mechanism of twins and then manipulating high‐density nanotwins to synergistically optimize thermoelectric and mechanical properties.
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