Introduction of porous structure: A feasible and promising method for improving thermoelectric performance of Bi2Te3 based bulks
Introduction of porous structure: A feasible and promising method for improving thermoelectric performance of Bi2Te3 based bulks
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DOI：
10.1016/j.jmst.2018.05.010
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发表时间：
2018-11
影响因子：
10.9
通讯作者：
Jie Hu;Xi’an Fan;Chengpeng Jiang;Bo Feng;Qiusheng Xiang;Guangqiang Li;Zhu He;Yawei Li
中科院分区：
文献类型：
--
作者：
Jie Hu;Xi’an Fan;Chengpeng Jiang;Bo Feng;Qiusheng Xiang;Guangqiang Li;Zhu He;Yawei Li
在电阻压制烧结过程中，通过人工控制烧结样品的相对密度，获得了具有不规则和随机取向气孔的p型多孔Bi0.4Sb1.6Te3块体。结果表明，多孔结构对材料的热电性能有显著的影响，尤其是由于载流子散射和声子散射的增强，材料的导电性和热导性得到了显著的改善。随着孔隙率的增加，电导率和热导率明显降低，塞贝克系数变化不大。令人鼓舞的是，热导率的降低可以补偿电性能的恶化，从而导致热电优值(ZT)的提高。对于相对密度为90%的样品，在333 K时，ZT值达到最大值1.0。遗憾的是，气孔率的增加也导致维氏硬度从51.71HV下降到27.74HV。值得一提的是，相对密度为90%的样品的维氏硬度虽然下降到40.12 HV，但仍是区熔样品(21.25 HV)的两倍左右。综上所述，在块材中适当引入孔洞结构，不仅可以提高Bi2Te3基合金的ZT值，而且可以减少原料的使用，节约生产成本。
The porous p-type Bi0.4Sb1.6Te3bulks containing irregularly and randomly oriented pores were obtained by artificially controlling the relative density of sintered samples during resistance pressing sintering process. It is demonstrated that the thermoelectric performances are significantly affected by the porous structure, especially for the electrical and thermal conductivity due to the enhanced carrier scattering and phonon scattering. The increasing porosity resulted in the obvious decrease in electrical and thermal conductivity, and little change in Seebeck coefficients. It is encouraging that the reduction of thermal conductivity can compensate for the deterioration of electrical performance, leading to the enhancement in thermoelectric figure of merit (ZT). The maximum ZT value of 1.0 was obtained for the sample with a relative density of 90% at 333 K. Unfortunately, the increase in porosity also brought in obvious degradations in Vickers hardness from 51.71 to 27.74 HV. It is worth mentioning that although the Vickers hardness of the sample with a relative density of 90% decreased to 40.12 HV, it was still about twice as high as that of the zone melting sample (21.25 HV). To summarize, introducing pores structure into bulks properly not only enhances the ZT value of Bi2Te3based alloys, but also reduces the use of raw materials and saves production cost.