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Effect of the Microstructure on the Thermoelectric Properties of Polycrystalline Lanthanum Chalcogenides

Published online by Cambridge University Press:  25 February 2011

A. Lockwood
Affiliation:
Jet Propulsion Laboratory, Pasadena, CA 91109
C. Wood
Affiliation:
Jet Propulsion Laboratory, Pasadena, CA 91109
J. Vandersande
Affiliation:
Jet Propulsion Laboratory, Pasadena, CA 91109
A. Zoltan
Affiliation:
Jet Propulsion Laboratory, Pasadena, CA 91109
J. Parker
Affiliation:
Jet Propulsion Laboratory, Pasadena, CA 91109
L. Danielson
Affiliation:
Thermal Electron Corporation, Waltham, MA 02254
M. Alexander
Affiliation:
Thermal Electron Corporation, Waltham, MA 02254
D. Whittenberger
Affiliation:
NASA Lewis, Cleveland, OH 44135
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Abstract

Small amounts of second phase materials can have important effects on the thermoelectric properties of polycrystalline γ-La3-xX4 (X-S, Te; 0<x<l/3). Microscopic examination by SEM of hot pressed La3–xTe4 samples has revealed from 1–5 vol. % of La202Te, an amount which is not detected by x-ray powder diffraction measurements. This amount of La202Te resulting from oxygen contamination can reduce the concentration of electrons by as much as 10% to 75% below the electron concentration calculated for single phase La3–xTe4 in the composition range of greatest interest. Small amounts of second phase materials can also lower the lattice thermal conductivity by scattering low frequency phonons These results indicate that microstructural effects should be considered when electrical and thermal properties of polycrystalline materials are analyzed.

Type
Research Article
Copyright
Copyright © Materials Research Society 1987

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References

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