SPS烧结工艺对填充方钴矿热电性能的影响

In this study, filled skutterudites Yb_0.3Co₄Sb₁₂ were synthesized by meltting quenching and annealing method. Then high-energy ball milling was employed to prepare micro/nano-structured powders. After that bulk materials were sintered by the technology of spark plasma sintering (SPS). The phase structure and morphology of the powder and the bulk materials were studied by XRD, SEM and TEM. The grain size after high-energy ball milling was 50~500 nm and the distribution is wide. The thermoelectric properties of the samples with different sintering processes like sintering temperature and sintering pressure were investigated in detail. The results show that with the increase of sintering temperature, the thermoelectric properties first increase and then decrease, which is caused by the increase of the sample density first and then the grain growth. And the densities and thermoelectric properties can be improved slightly by increasing sintering pressure. After sintered at about 875 K with 90 MPa, the thermoelectric properties of the material are the best, and the thermoelectric figure of merit (ZT value) reached 1.19 at 750 K.