Interplay of chemical expansion, Yb valence, and low temperature thermoelectricity in the YbCu2Si2-xGex solid solution

Gloria J. Lehr, Donald T. Morelli

Research output: Contribution to journalArticle

  • 2 Citations

Abstract

YbCu2Si2 is a promising low temperature thermoelectric material because of the large broad peak in the Seebeck coefficient near 100 K combined with a low electrical resistivity. This behavior is thought to arise from fluctuating, or intermediate, valence effects due to partial occupation of Yb 4f energy states near the Fermi level. Previous studies of the magnetic properties under pressure have demonstrated that the average Yb valence is sensitive to the contraction of unit cell volume. By forming a solid solution of YbCu2Si2 with YbCu2Ge2, an isostructural compound with a larger unit cell volume, here we examine the subtle effects of lattice expansion on the transport properties and average Yb valence. We observe a shift in the peak of the Seebeck coefficient towards higher temperatures, as well as an enhanced power factor in the solid solutions. At the same time, a reduction in thermal conductivity due to alloy scattering enhances the thermoelectric figure of merit. Chemical pressure effects may thus be utilized to control and optimize the thermoelectric properties of these alloys in the cryogenic temperature range.

LanguageEnglish (US)
Article number135101
JournalJournal of Applied Physics
Volume117
Issue number13
DOIs
StatePublished - Apr 7 2015

Profile

thermoelectricity
solid solutions
Seebeck effect
valence
expansion
thermoelectric materials
pressure effects
cryogenic temperature
cells
figure of merit
occupation
contraction
thermal conductivity
transport properties
magnetic properties
electrical resistivity
shift
scattering
energy

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Interplay of chemical expansion, Yb valence, and low temperature thermoelectricity in the YbCu2Si2-xGex solid solution. / Lehr, Gloria J.; Morelli, Donald T.

In: Journal of Applied Physics, Vol. 117, No. 13, 135101, 07.04.2015.

Research output: Contribution to journalArticle

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