Structure and Thermoelectric Properties of Te- and Ge-Doped Skutterudites CoSb_2.875−xGe_0.125Te_x

Authors: Su, XianLi¹; Li, Han¹; Guo, QuanSheng¹; Tang, Xinfeng²; Zhang, Qingjie¹; Uher, Ctirad³

Source: Journal of Electronic Materials, Volume 40, Number 5, May 2011 , pp. 1286-1291(6)

Publisher: Springer

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Abstract:

n-Type CoSb_2.875−xGe_0.125Te_x (x = 0.125 to 0.275) compounds with different Te contents have been synthesized by a melt-quench-anneal-spark plasma sintering method, and the effects of Te content on the structure and thermoelectric properties have been investigated. The results show that all specimens exhibited n-type conduction characteristics. The solubility limit of Te in CoSb_2.875−xGe_0.125Te_x is found to be x = 0.25. The solubility of Te in CoSb₃ is increased through charge compensation of the element Ge. The room-temperature carrier concentration N _p of CoSb_2.875−xGe_0.125Te_x skutterudites increases with increasing Te content, and the compounds possess high power factors. The maximum power factor of 3.89 × 10⁻³ W m⁻¹ K⁻² was obtained at 720 K for the CoSb_2.625Ge_0.125Te_0.25 compound. The thermal conductivity decreases dramatically with increasing Te content due to strong point defect scattering. The maximum value of the thermoelectric figure of merit ZT = 1.03 was obtained at 800 K for CoSb_2.625Ge_0.125Te_0.25, benefiting from a lower thermal conductivity and a higher power factor. The figure of merit is competitive with values reported for single-filled skutterudites.

Keywords: Te-doped skutterudite; structure; thermoelectric properties

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s11664-011-1617-x

Affiliations: 1: State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070, China 2: State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070, China, Email: tangxf@whut.edu.cn 3: Department of Physics, University of Michigan, Ann Arbor, MI, 48109, USA

Publication date: 2011-05-01