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Anisotropy in Thermoelectric Properties of CsBi4Te6

Published online by Cambridge University Press:  01 February 2011

Duck-Young Chung
Affiliation:
Department of Chemistry and Center for Fundamental Materials Research, Michigan State University, East Lansing, MI 48824, USA
S. D. Mahanti
Affiliation:
Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
Wei Chen
Affiliation:
Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA.
Citrad Uher
Affiliation:
Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA.
Mercouri G. Kanatzidis
Affiliation:
Department of Chemistry and Center for Fundamental Materials Research, Michigan State University, East Lansing, MI 48824, USA
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Abstract

CsBi4Te6 (ZT ∼ 0.8 at 225 K) shows highly anisotropic features in its crystal morphology and structure as expressed by the parallel infinite [Bi4Te6] rods which are linked via Bi-Bi bonds. Band calculations also point to a significant anisotropy in the carrier effective masses, and for this reason we examined the anisotropic thermoelectric properties of CsBi4Te6. The electrical conductivity, thermopower and thermal conductivity were measured along the three different crystallographic directions of the monoclinic structure of CsBi4Te6. These measurements were performed on samples with different degrees of doping. The strong charge transport anisotropy of these samples was confirmed and also observed that the thermopower values along the c-axis direction (which is perpendicular to the layer of Cs atoms) was negative (-80 μV/K) while those along the needle direction (b-axis) and parallel to the [Bi4Te6] layers (a-axis) were p-type (50–100 μV/K at room temperature. Other anisotropic features in the crystal growth habit, electronic band structure, and electrical and thermal conductivities are also presented.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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References

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