细晶Bi2Te3块体材料的制备及其热电性能

Preparation and Thermoelectric Properties of Bi2Te3 Fine-grained Bulk Materials

摘要:

采用惰性气体保护蒸发-冷凝 (IGC) 法制备了纳米Bi及Te粉末，结合机械合金化 (MA) 和放电等离子烧结 (SPS) 工艺，在不同烧结温度 (663~723 K) 下制备出了n型Bi2Te3细晶块体材料。利用X射线衍射分析(XRD)确定机械合金化粉末和SPS烧结块体的物相组成，借助TEM观察了粉体的粒度及形貌，SEM观察了块体试样断口显微组织结构。在323~473 K温度范围内测试了烧结块体的电热输运特性。实验结果表明：纳米粉末合成的细晶Bi2Te3与粗晶材料相比，电输运性能变化不大，热导率大幅度降低，在423 K时，热导率由粗晶材料的1.93 W/m·K降至1.29 W/m·K，并且在693 K烧结的细晶块体的无量纲热电优值 (ZT) 在423 K时取得最高ZT值达到0.68

Abstract:

Bismuth and Tellurium nanoparticles were prepared by evaporation-condensation method in argon atmosphere, and n-type Bi2Te3 fine-grained thermoelectric bulk materials were fabricated by spark plasma sintering (SPS) at different temperatures from 663 to 723 K using mechanically alloyed (MA) powders. The phase compositions of powder and bulk samples were characterized by X-ray diffraction (XRD). The sizes and microscopic structures of nanoparticles and fractured cross section of the bulk samples were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. The thermoelectric transport properties were measured at 323~473 K. The results show that electrical transport properties are almost unchanged but thermal conductivity is reduced significantly from 1.93 W/m·K to 1.29 W/m·K at 423 K for the fine-grained bulks prepared by nanoparticles comparing with coarse-grained materials. The maximum ZT value after SPS at 693 K reaches 0.68 at 423 K