Influence of fullerene dispersion on high temperature thermoelectric properties of BayCo4Sb12-based composites

Ba y Co 4 Sb 12 -based composites with dispersed fullerene or barium fulleride have been synthesized by the solid state reaction and spark plasma sintering technique. When fullerene was used as a dispersed phase, a part of barium in the filled skutterudite reacted with fullerene to form barium fullerides. Most of the extended impurity aggregated to form large defects at the grain boundaries of the matrix. The thermoelectric properties of the composites were measured from room temperature to 850 K. Both the electrical conductivity and thermal conductivity decreased with increasing impurity contents. We attributed these significant reductions to enhanced grain-boundary scattering of charge carriers and phonons. A large ZT value of 1.3 was obtained in a composite with an appropriate content of fullerene dispersants.