Enhanced Thermoelectric Properties of Melt-Spun p-Type Yb0.9Fe3CoSb12

초록

We herein report an enhancement of the thermoelectric properties of p-type Yb0.9Fe3CoSb12 skutterudite by melt spinning combined with spark plasma sintering (SPS). By thermal aging (873 K for 120 h) of the starting Yb0.9Fe3 CoSb12 compound for melt spinning, fabricated by conventional melting and quenching, highly dense single phase bulks with reduced grain sizes of similar to 300 nm are successfully fabricated after SPS. The power factor value of the sample (similar to 3.6 mW m(-1) K-2 at 723 K) is increased, benefiting from an enhancement of the electrical conductivity due to the elimination of the secondary phase CoSb2 during the thermal aging process. In addition, lattice thermal conductivity is significantly decreased due to the reduced grain size, thus intensifying the grain boundary phonon scattering. Through these synergetic effects, the maximum dimensionless figure of merit ZT increases by 25% (0.70 at 723 K) compared to a pristine sample with microscale grains.

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