Open AccessNanotwins Strengthening High Thermoelectric Performance Bismuth Antimony Telluride Alloys
Author(s) -
Qin Haixu,
Qu Wanbo,
Zhang Yang,
Zhang Yongsheng,
Liu Zihang,
Zhang Qian,
Wu Haijun,
Cai Wei,
Sui Jiehe
Publication year - 2022
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202200432
Subject(s) - materials science , thermoelectric effect , bismuth telluride , deformation mechanism , annealing (glass) , microstructure , alloy , deformation (meteorology) , thermoelectric materials , grain boundary , nanocrystalline material , severe plastic deformation , composite material , nanotechnology , thermodynamics , thermal conductivity , physics
Bi 2 Te 3 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 Bi 2 Te 3 based materials. Herein, thorough microstructure characterizations are employed on a series of Bi 0.4 Sb 1.6 Te 3+ 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) 2 Te 3 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 Bi 2 Te 3 based alloys for miniature device development.