Issue 40, 2015

Enhanced average thermoelectric figure of merit of n-type PbTe1−xIx–MgTe

Abstract

The thermoelectric properties of sintered samples of n-type PbTe1−xIxyMgTe (x = 0.0012–0.006; y = 0 and 1%) were investigated over the temperature range of 300 K to 900 K. Scanning electron microscopy revealed two different length scales of grains in samples with higher I and MgTe contents, while a homogenous microstructure for samples with a lower dopant content. Transmission electron microscopy revealed ubiquitous spherical nanoprecipitates in PbTe1−xIx with MgTe and nanoscale disk like precipitates in both, PbTe1−xIx with and without MgTe. The nanostructured PbTe showed higher Seebeck coefficients than expected values. We also observed a slower rate of increase in the electrical resistivity with rising temperature in PbTe1−xIxyMgTe below ∼550 K, leading to a higher thermoelectric power factor. The nanostructures and mixed microstructures scatter phonons, reducing the lattice thermal conductivity as low as 0.4 W K−1 m−1 at 600 K. A high ZT of 1.2 at 700 K was achieved as well as a high average ZT of 0.8 was observed in PbTe0.996I0.004–1 mol% MgTe for a cold-side temperature of 303 K and a hot-side temperature of 873 K.

Graphical abstract: Enhanced average thermoelectric figure of merit of n-type PbTe1−xIx–MgTe

Supplementary files

Article information

Article type
Paper
Submitted
05 jun 2015
Accepted
31 jul 2015
First published
03 aug 2015

J. Mater. Chem. C, 2015,3, 10401-10408

Author version available

Enhanced average thermoelectric figure of merit of n-type PbTe1−xIx–MgTe

P. Jood, M. Ohta, M. Kunii, X. Hu, H. Nishiate, A. Yamamoto and M. G. Kanatzidis, J. Mater. Chem. C, 2015, 3, 10401 DOI: 10.1039/C5TC01652E

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