Microstructural analysis and thermoelectric properties of skutterudite CoSb3 materials produced by melt spinning and spark plasma sintering

Skutterudite CoSb3 thermoelectric materials were synthesized by a combination of melt spinning (MS) and consolidation by spark plasma sintering (SPS). Microstructural analysis was carried out on the MS-SPS samples using various analytical techniques such as XRD, SEM, EBSD and DSC/TGA. In the melt-spun ribbons, the initial microstructure consisted of a multiphase mixture of Sb and CoSbx (x = 1, 2, or 3) where CoSb3 is the only thermoelectric phase. Subsequent SPS processing caused conversion of other phases present (Sb, CoSb and CoSb2) into single-phase CoSb3 and recrystallization concurrently. The phase conversion mechanism has been explained in the present work using a thermodynamic interpretation. Thermoelectric transport measurement results show that the thermal conductivity of MS-SPS sample was significantly decreased as compared with that of the sample prepared by traditional methods combined with SPS (TM-SPS) due to the reduction of its grain size. Compared with TM-SPS sample, MS-SPS sample has a high ZT value at room temprerature because of its high electrical conductivity and low lattice thermal conductivity.

Automated summary

Skutterudite CoSb3 thermoelectric materials were synthesized using melt spinning and spark plasma sintering, with microstructural analysis revealing high ZT value and low thermal conductivity due to grain size reduction.