Thermoelectric Properties of Two-Phase PbTe with Indium Inclusions

Bali, Ashoka and Kim, Il-Ho and Rogl, Peter and Mallik, Ramesh Chandra (2014) Thermoelectric Properties of Two-Phase PbTe with Indium Inclusions. In: JOURNAL OF ELECTRONIC MATERIALS, 43 (6). pp. 1630-1638.

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Abstract

The thermoelectric figure of merit (zT) can be increased by introduction of additional interfaces in the bulk to reduce the thermal conductivity. In this work, PbTe with a dispersed indium (In) phase was synthesized by a matrix encapsulation technique for different In concentrations. x-Ray diffraction analysis showed single-phase PbTe with In secondary phase. Rietveld analysis did not show In substitution at either the Pb or Te site, and this was further confirmed by room-temperature Raman data. Low-magnification (similar to 1500x) scanning electron microscopy images showed micrometer-sized In dispersed throughout the PbTe matrix, while at high magnification (150,000x) an agglomeration of PbTe particles in the hot-pressed samples could be seen. The electrical resistivity (rho) and Seebeck coefficient (S) were measured from 300 K to 723 K. Negative Seebeck values showed all the samples to be n-type. A systematic increase in resistivity and higher Seebeck coefficient values with increasing In content indicated the role of PbTe-In interfaces in the scattering of electrons. This was further confirmed by the thermal conductivity (kappa), measured from 423 K to 723 K, where a greater reduction in the electronic as compared with the lattice contribution was found for In-added samples. It was found that, despite the high lattice mismatch at the PbTe-In interface, phonons were not scattered as effectively as electrons. The highest zT obtained was 0.78 at 723 K for the sample with the lowest In content.

Item Type:	Journal Article
Publication:	JOURNAL OF ELECTRONIC MATERIALS
Publisher:	SPRINGER
Additional Information:	Copyright for this article belongs to the SPRINGER, USA.
Keywords:	Thermoelectric; scanning electron microscopy; Raman spectroscopy; interfaces; thermal conductivity
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	16 Jul 2014 09:02
Last Modified:	16 Jul 2014 09:02
URI:	http://eprints.iisc.ac.in/id/eprint/49428

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