a1 State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
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.
(Received December 14 2010)
(Accepted March 15 2011)
a) These authors contributed equally to the work.