Coherent Sb/CuTe Core/Shell Nanostructure with Large Strain Contrast Boosting the Thermoelectric Performance of n-Type PbTe |
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Authors: | Shixuan Liu Yong Yu Di Wu Xiao Xu Lin Xie Xiaolian Chao Michel Bosman Stephen J Pennycook Zupei Yang Jiaqing He |
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Affiliation: | 1. School of Materials Science and Engineering, Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Normal University, Xi'an, 710062 China;2. Department of Physics, Southern University of Science and Technology, Shenzhen, 518055 China;3. Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575 Singapore |
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Abstract: | The exploration of n-type PbTe as thermoelectric materials always falls behind its p-type counterpart, mainly due to their quite different electronic band structure. In this work, elemental Sb and Cu2Te are introduced into an n-type base material (PbTe)81-Sb2Te3. The introduction of extra Sb can effectively tune the concentration of electrons; meanwhile, Sb precipitates can also scatter low-energy electrons (negatively contribute to the Seebeck coefficient) thus enhance the overall Seebeck coefficient. The added Cu2Te is found to always co-precipitate with Sb, forming an interesting Sb/CuTe core/shell structure; moreover, the interface between core/shell precipitates and PbTe matrix simultaneously shows coherent lattice and strong strain contrast, beneficial for electron transport but adverse to phonon transport. Eventually, a peak figure of merit ZTmax ≈ 1.6 @ 823K and simultaneously an average ZT ≈ 1.0 (323–823 K) are realized in the (PbTe)81Sb2Te3-0.6Sb-2Cu2Te sample, representing the state of the art for n-type PbTe-based thermoelectric materials. Moreover, for the first time the three existing forms of Cu atoms in Cu2Te alloyed PbTe are unambiguously clarified with aberration-corrected scanning transmission electron microscopy (Cs-STEM). |
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Keywords: | coherent interface core-shell structure energy filtering n-type PbTe strain contrast thermoelectrics |
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