Improved thermoelectric performance of Te-doped and CNT dispersed CoSb3 skutterudite bulk materials via HTHP

Abstract

Carbon nanotubes (CNTs) were dispersed for the first time in Co₄Sb_11.5Te_0.5 skutterudite bulk materials via a high temperature and high pressure (HTHP) method, and the effects of the content of Te and CNTs on the structure and thermoelectric properties were investigated at different pressures. Compared with other traditional methods, the processing time of the HTHP method was sharply reduced from a few days to half an hour. With increasing temperature, the power factor evidently increases, and the thermal conductivity distinctly declines. The thermoelectric figure of merit (ZT) of the Co₄Sb_11.5Te_0.5 + 0.25 vol% CNTs synthesized at 3.5 GPa reaches 1.32 at 773 K, which is strongly enhanced in comparison to other results. Macroscopically speaking, the excellent thermoelectric transport properties of our samples are considered to be the common effect of high pressure, dopant atoms and dispersed CNTs. On the micro level, abundant grain boundaries produced by the smaller grain size, disorder in the lattice orientation, dislocations and the possible “nanodots” commonly existing in our samples have an improving effect on the thermoelectric performance.