High figure of merit in nanostructured n-type KPbmSbTe m+2 thermoelectric materials

Pierre F.P. Poudeu, Aurélie Guéguen, Chun I. Wu, Tim Hogan, Mercouri G. Kanatzidis

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89 Citations (Scopus)

Abstract

We demonstrate that the KPbmSbTe2+m system (PLAT-m for tellurium, antimony, lead potassium, m = 19-21) of materials exhibits high thermoelectric performance. Samples with compositions K1-xPb m+δSb1-γTem+2 were prepared using several combinations of x, δ, γ and m and their thermoelectric properties were investigated in the temperature range of 300 - 800 K. All K 1-xPbm+δSb1+γTem+2 samples exhibited n-type conduction over the measured temperature range. Their lattice thermal conductivities were found to be significantly reduced when compared to PbTe and even AgPbmSbTem+2 For example, for K0.95Pb20Sb1.2Te22 a lattice thermal conductivity as low as 0.4 W/(m, K) was estimated at 650 K (based on a Lorenz number of 1.25 x 10-8 W, Ω/K2). High resolution transmission electron microscopy on several samples revealed a widely dispersed nanoscale particle with varying size and shape endotaxially embedded inside a PbTe-rich matrix which is believed to be responsible for the reduced lattice thermal conductivity of K1-x Pbm+δTem+2 materials. Because of their small size. the nanoinclusions are coherent with the matrix and therefore do not markedly degrade the electrical conductivity of the materials. As a result, very high figures of merit are achieved at high temperature for several compositions. For K0.95Pb20Sb 1.2Te22, a maximum figure of merit ZT ∼ 1.6 was obtained around 750 K. This value is similar to that of n-type LAST-18 and is two times larger than that of the-state-of-the-art n-type PbTe.

Original languageEnglish
Pages (from-to)1046-1053
Number of pages8
JournalChemistry of Materials
Volume22
Issue number3
DOIs
Publication statusPublished - Feb 9 2010

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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