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Enhanced thermoelectric properties of n-type Bi2Te2.7Se0.3 semiconductor by manipulating its parent liquid state

Author:
Zhu, Bin, Yu, Yuan, Wang, Xiao-yu, Zu, Fang-qiu, Huang, Zhong-yue
Source:
Journal of materials science 2017 v.52 no.14 pp. 8526-8537
ISSN:
0022-2461
Subject:
air, alloys, cooling, glass, melting, methodology, nanoparticles, pressing, semiconductors, thermal conductivity
Abstract:
To enhance the properties of bulk thermoelectric (TE) materials, preparation methods have been intensively developed with advanced techniques, e.g., zone-melting, Bridgman or Czochralski unidirectional methods, hot pressing or spark plasma sintering, that follow various complicated synthesis steps. However, these innovative methods remain less competitive than conventional techniques for large-scale production and application. Here, we report that, by manipulating the liquid state of the Bi₂Te₂.₇Se₀.₃ alloy doped with KI, n-type bulk specimens with desired TE performance can be simply solidified by air cooling and without costly equipments. The specimens solidified from the parent melt experienced temperature-induced liquid–liquid structural transition, which is indicated by the resistivity behavior of the liquid, the presence of a refined matrix and eutectics, and the observation of more nanoparticles and a higher density of lattice defects. It was confirmed these refined multiscale refined structures lead to a “phonon glass electron crystal” effect, i.e., a much lower lattice thermal conductivity but a much higher power factor (PF). The present method, which synergistically obtains higher PF and lower thermal conductivity, could also be applied to other TE compounds.
Agid:
5728069