Fe doped skutterudite CoSb3 with a nominal composition of FexCo1-xSb12 (0≤x≤2.5) have been synthesized by mechanical alloying (MA) of elemental powders, followed by vacuum hot pressing. Phase transformations during mechanical alloying and vacuum hot pressing were systematically investigated using XRD. Single phase skutterudite was successfully produced by vacuum hot pressing using as-milled powders without subsequent annealing. However, second phase of FeSb2 was found to exist in case of x≥2, suggesting the solubility limit of Fe with Co in this system. Thermoelectric properties as functions of temperature and Fe contents were evaluated for the hot pressed specimens. Fe doping up to x=1.5 with Co in FexCo4-xSb12 appeared to increase thermoelectric figure of merit (ZT) and the maximum ZT was found to be 0.78 at 525K in this study.

Undoped powders were synthesized by mechanical alloying (MA) of elemental powders using a nominal stoichiometric composition. Nano-structured, single-phase skutterudite was successfully produced by vacuum hot pressing (VHP) using MA powders without subsequent annealing. Phase transformations during synthesis were investigated using XRD, and microstructure was observed using SEM and TEM. Thermoelectric properties in terms of Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit(ZT) were systematically measured and compared with the results of analogous studies. Lattice thermal conductivity was reduced owing to increasing phone scattering in nano-structured MA , leading to enhancement in the thermoelectric figure of merit. MA associated with VHP technique offers an alternative potential processing route for the process of skutterudite.