Enhanced Density-of-States Effective Mass and Strained Endotaxial Nanostructures in Sb-Doped Pb 0.97 Cd 0.03 Te Thermoelectric Alloys

Gangjian Tan*, Xiaomi Zhang, Shiqiang Hao, Hang Chi, Trevor P. Bailey, Xianli Su, Ctirad Uher, Vinayak P. Dravid, Chris Wolverton, Mercouri G. Kanatzidis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Here we report that CdTe alloying and Sb doping increase the density-of-states effective mass and introduce endotaxial nanostructuring in n-type PbTe, resulting in enhanced thermoelectric performance. A prior theoretical prediction for the presence of resonance states in the conduction band of this system, however, could not be confirmed. An amount of 3 mol % CdTe alloying widens the band gap of PbTe by 50%, leading to enhanced carrier effective mass and Seebeck coefficient. This effect is even more pronounced at high temperatures where the solubility of CdTe increases. At 800 K, when the carrier concentration is the same (4 × 10 19 cm -3 ), the Seebeck coefficient of CdTe-alloyed PbTe is -195 μV K -1 , 16% higher than that of the Cd-free control sample (-168 μV K -1 ). Sb doping considerably increases the electron concentration of Pb 0.97 Cd 0.03 Te, giving rise to optimized power factors of ∼17 μW cm -1 K -2 at 800 K. More importantly, Sb induces strained endotaxial nanostructures evenly distributed in the matrix. These Sb-rich nanostructures account for the ∼40% reduction in the lattice thermal conductivity over the whole measured temperature range. As a result, a maximum ZT of 1.2 is attained at 750 K in 0.5 mol % Sb-doped Pb 0.97 Cd 0.03 Te alloys.

Original languageEnglish (US)
Pages (from-to)9197-9204
Number of pages8
JournalACS Applied Materials and Interfaces
Volume11
Issue number9
DOIs
StatePublished - Mar 6 2019

Keywords

  • electronic structure
  • lead telluride
  • nanostructuring
  • thermal conductivity
  • thermoelectric

ASJC Scopus subject areas

  • Materials Science(all)

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