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Published 2010 | Published
Journal Article Open

Synthesis, structure, magnetism, and high temperature thermoelectric properties of Ge doped Yb_(14)MnSb_(11)

Abstract

The Zintl phase Yb_(14)MnSb_(11) was successfully doped with Ge utilizing a tin flux technique. The stoichiometry was determined by microprobe analysis to be Yb_(13.99(14))Mn_(1.05(5))Sb_(10.89(16))Ge_(0.06(3)). This was the maximum amount of Ge that could be incorporated into the structure via flux synthesis regardless of the amount included in the reaction. Single crystal X-ray diffraction could not unambiguously determine the site occupancy for Ge. Bond lengths varied by about 1% or less, compared with the undoped structure, suggesting that the small amount of Ge dopant does not significantly perturb the structure. Differential scanning calorimetry/thermogravimetry (DSC/TG) show that the doped compound's melting point is greater than 1200 K. The electrical resistivity and magnetism are virtually unchanged from the parent material, suggesting that Yb is present as Yb^(2+) and that the Ge dopant has little effect on the magnetic structure. At 900 K the resistivity and Seebeck coefficient decrease resulting in a zT of 0.45 at 1100 K, significantly lower than the undoped compound.

Additional Information

© 2010 Royal Society of Chemistry. Received 30th September 2009, Accepted 4th November 2009. First published as an Advance Article on the web 30th November 2009. We thank Marilyn Olmstead for assistance with crystallography and Sarah Roeske for assistance with microprobe analysis. Portions of this work were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. This research was funded by NSF DMR-0600742 and the Beckman Foundation at Caltech.

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August 19, 2023
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