Thermal conductivity of nanostructured Fe<inf>0.04</inf>Co<inf>0.96</inf>Sb<inf>3</inf> skutterudite

In this study, Fe0.04Co0.96Sb3 nanopowder was synthesized using radio frequency induction plasma, starting from mechanically milled Fe, Co, and Sb powders. The as-synthesized powder was found to contain CoSb3, FeSb2, CoSb, and elemental Sb. Annealing of the synthesized powder at 600 °C for 12 h under argon atmosphere increased the fraction of CoSb3. Spark plasma sintering of the annealed powder was carried out at 625 °C under 60 MPa pressure for fabrication into bulk nanostructured material. Thermal conductivity (k) of disks thus fabricated was found to be 1.78 ± 0.16 W/m.K at room temperature, which is significantly lesser than its microcrystalline counterpart (5.58 ± 0.60 W/m.K). Such a reduction in k could mainly be attributed to the enhanced phonon scattering occurring at the grain boundaries and interfaces present in the bulk nanostructured Fe0.04Co0.96Sb3 sample, which is an added advantage for its use in the thermoelectric devices.