Thermoelectric nanocomposite from the metastable void filling in caged skutterudite


We report a novel approach to realize the formation of well-distributed nanodispersions in n-type filled skutterudite through the manipulation of metastable void fillers by a designed sophisticated process of materials synthesis. Metastable Ga filling in CoSb3 is proved to happen at high temperature. The subsequent controlled annealing procedure drives Ga out of the crystal voids and finally leads to the homogeneous dispersion of GaSb nanodots with an average size of 11 nm in CoSb3 matrix. The grain size of nanodispersions can be manipulated by the controlled cooling procedure. The well-distributed nanodispersions are observed to enhance Seebeck coefficients and reduce lattice thermal conductivity at low temperature. Therefore, the thermoelectric performance of nanocomposite is improved in the whole temperature range. The highest figure of merit (ZT) is obtained to be 1.45 at 850 K, and an average ZT of 0.99 in 300−850 K is achieved for Yb0.26Co4Sb12/0.2GaSb nanocomposite.

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We thank Prof. F.F. Xu and Ms. M.L. Ruan (Shanghai Institute of Ceramics, Chinese Academy of Sciences) for their careful TEM characterization and helpful discussions and Prof. X.F. Sun (Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China) for his kind low temperature thermal conductivity measurements. This work was partially supported by the National Basic Research Program of China (2007CB607502), Natural Science Foundation of China project (No. 50821004), and Corning Inc.

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Correspondence to Zhen Xiong or Lili Xi or Lidong Chen or Wenqing Zhang.



FIG. A1.

Powder x-ray diffraction patterns of the samples.

FIG. A2.

Scanning electron microscopy images for the polished surface after eroding.

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Xiong, Z., Xi, L., Ding, J. et al. Thermoelectric nanocomposite from the metastable void filling in caged skutterudite. Journal of Materials Research 26, 1848–1856 (2011).

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