多壁碳纳米管复合BiSbTe材料的热电性能

Effect of Multiwall Carbon Nanotubes on the Thermoelectric Properties of BiSbTe Based Composites

摘要:

研究了BiSbTe/多壁碳纳米管(MWCNTs)复合材料的球磨法制备及其热电性能(300~500 K)。采用商用BiSbTe块体作为基体材料,利用球磨及压力辅助的感应加热烧结进行致密化得到了不同复合比的BiSbTe/0.5、1.0 vol% MWCNTs复合材料。复合MWCNTs后,引入的纳米复合结构增强了声子散射,大幅降低了热导率,同时由于载流子散射的增强和较低的致密度使电导率恶化。尽管电导率降低但热导率得到抑制,BiSbTe/1.0 vol% MWCNT复合材料的热电优值与BiSbTe基体接近。结果表明,优化加工参数获得更高的致密度可以优化BiSbTe/MWCNTs复合材料的热电性能。

Abstract:

The effects of ball milling with simultaneous addition of multiwall carbon nanotubes (MWCNTs) on the thermoelectric properties of BiSbTe based nanocomposites were investigated in the temperature range from 300 K to 500 K. The MWCNTs in 0.5 vol% and 1.0 vol% were incorporated in fine BiSbTe powder that was processed from commercially available BiSbTe lumps and consolidated through pressure assisted induction heated sintering. The results show that the electrical and thermal transport properties of the composites are altered substantially. The thermal conductivity of the composites decreases significantly from pure BiSbTe bulk due to enhanced phonon scattering caused by nanostructuring and nanoinclusion effects. While the electrical conductivity deteriorates with the addition of MWCNTs, which is attributed partly to enhanced electron scattering and predominantly, rather low densification of the composites. The figure of merit of 1.0 vol% MWCNTs/BiSbTe composite remains close to that of pristine BiSbTe, snice the decrease in electrical conductivity is compensated by the significant reduction in thermal conductivity. The result suggests that optimizing the processing parameters for enhanced densification could improve the figure of merit for BiSbTe based MWCNTs composites.