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Structural Studies of GeTe-AgSbTe2 Alloys

Published online by Cambridge University Press:  01 February 2011

Alan Thompson ,
Jeff Sharp ,
C.J Rawn  and
B.C. Chackoumakos
Alan Thompson
Affiliation:
[email protected], Marlow Industries, Materials Research and Development, 10451 Vista Park Rd., Dallas, TX, 75238, United States, 214-342-4233
Jeff Sharp
Affiliation:
[email protected], Marlow Industries, Materials Research and Development, 10451 Vista Park Rd., Dallas, TX, 75238, United States
C.J Rawn
Affiliation:
[email protected], Oak Ridge National Laboroatory, Materials Science and Technology, Oak Ridge, TX, 37831, United States
B.C. Chackoumakos
Affiliation:
[email protected], Oak Ridge National Laboroatory, Materials Science and Technology, Oak Ridge, TX, 37831, United States
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Abstract

GeTe, a small bandgap semiconductor that has native p-type defects due to Ge vacancies, is an important constituent in the thermoelectric material known as “TAGS” [1]. TAGS is an acronym for alloys of GeTe with AgSbTe2, and compositions are normally designated as TAGS-x, where x is the fraction of GeTe. TAGS-85 is the most important with regard to applications, and there also is commercial interest in TAGS-80. The crystal structure of GeTe1+δ has a composition-dependent phase transformation at a temperature ranging from 430°C (δ = 0) to ∼ 400°C (δ = 0.02) [2]. The high temperature form is cubic. The low temperature form is rhombohedral for δ < 0.01, as is the case for good thermoelectric performance. Addition of AgSbTe2 shifts the phase transformation to lower temperatures, and one of the goals of this work is a systematic study of the dependence of transformation temperature on the parameter x. We present results on phase transformations and associated instabilities in TAGS compositions in the range of 70-85 at.% GeTe.

Keywords

thermoelectricityelectrical propertiessecond phases
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1044: Symposium U – Thermoelectric Power Generation , 2007 , 1044-U03-09
Copyright
Copyright © Materials Research Society 2008

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References

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