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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(663～723K)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323～473K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423K时,热导率由粗晶材料的1.93W/m·K降至1.29W/m·K,并且在693K烧结的细晶块体的无量纲热电优值(ZT)在423K时取得最高ZT值达到0.68。
Nanostructured Bi and Te powders were prepared by inert gas evaporation-condensation (IGC) method. In combination with mechanical alloying (MA) and spark plasma sintering (SPS) Bi2Te3 fine-grained bulk material. The phase composition of mechanical alloying powder and SPS sintered compact was determined by X-ray diffraction (XRD). The particle size and morphology were observed by TEM. The microstructure of the fracture was observed by SEM. In the temperature range of 323 ~ 473K, the electric heat transfer characteristics of the sintered block were tested. The experimental results show that the thermal conductivity of the thin crystalline Bi2Te3 synthesized by nano-powder is less than that of the coarse-grained material, and its thermal conductivity is greatly reduced. The thermal conductivity at 423K is 1.93W / m · K down to 1.29 W / m · K, and the maximum ZT value of 0.27 at 423 K for the dimensionless thermoelectric figure of merit (ZT) of the sintered bulk of 693 K was achieved.