Coherent Sb/CuTe Core/Shell Nanostructure with Large Strain Contrast Boosting the Thermoelectric Performance of n‐Type PbTe. (23rd October 2020)

• Record Type: Journal Article
• Authors: Liu, Shixuan; Yu, Yong; Wu, Di; Xu, Xiao; Xie, Lin; Chao, Xiaolian; Bosman, Michel; Pennycook, Stephen J.; Yang, Zupei; He, Jiaqing
• Is Part Of: Advanced functional materials. Volume 31:Number 5(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-10-23
• Subjects: coherent interface -- core‐shell structure -- energy filtering -- n‐type PbTe -- strain contrast -- thermoelectrics; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202007340
• Languages: English
• ISSNs: 1616-301X

Abstract

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 Cu2 Te are introduced into an n‐type base material (PbTe)81 ‐Sb2 Te3 . 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 Cu2 Te 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 ZT max ≈ 1.6 @ 823K and simultaneously an average ZT ≈ 1.0 (323–823 K) are realized in the (PbTe)81 Sb2 Te3 ‐0.6Sb‐2Cu2 Te 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 Cu2 Te alloyed PbTe are unambiguously clarified with aberration‐corrected scanning transmission electron microscopy (Cs ‐STEM). Abstract : Synergetic addition of elemental Sb and Cu2 Te in n‐type PbTe eventually forms a novel Sb/CuTe core/shell nanostructure sitting coherently in the PbTe matrix but simultaneously with large strain contrast; this unique core/shell microstructure can benefit charge carrier transport but act adversely to phonon transport, resulting in a decoupling of electrical and heat conducting.