放电等离子烧结制备的Bi2Te3／Sb2Te3复合材料的热电性能

Thermoelectric performance of Bi2Te3 / Sb2Te3 nanocomposites prepared by spark plasma sintering

研究了用低温湿化学法和水热法制备纳米级的Bi2Te3和sb挪e3颗粒，并通过透射电镜观察其微观形貌。Bi2Te3粉末的微观形貌为直径在30-50n之间的片状小颗粒，而sb2Te3颗粒的微观形貌为薄带状，直径约为70nm，长度则为从150-300nm不等，并对其晶体的形核和长大机理进行了讨论。认为，纳米小颗粒状的Bi2Te3晶体可能是通过“表面形核和侧向生长”形成的产物，而薄带状的sb2Te3晶体可能是在Te块解体形成的条带状碎屑基础上形成的。用放电等离子烧结法（spark plasma sintering）制备不同比例的Bi2Te3／Sb2Te3块状复合材料，测量并比较了其热电性能。通过改变Bi2Te3的量，可以提高复合材料的电性能。成分不同的层片间的散射，能更有效地降低块体材料的热导率。在500K的温度下，Bi2Te3和sb2Te3以摩尔比为1：1复合烧结的试样的热导率低达0．7W／（m·K）。进一步优化Bi2Te3和sb2Te3的复合比例，其热电性能可能会有进一步的提高。

Bi2Te3 and Sb2Te3 thermoelectric materials have been synthesized by low temperature aqueous chemical method in an open beaker and hydrothermal synthesis in a closed autoclave, respectively. The microstructure investigations show that the Bi2Te3 flakes have an average diameter of about 40nm, while about 70 nm for the Sb2Te3 belts, and with the length varying from about 150 to 300 nm. It indicates that the low-temperature aqueous chemical method can synthesize the nanostructure powders more easily than the hydrothermal method. Four bulk samples were prepared by spark plasma sintering with different ratios of Bi2Te3 and Sb2Te3. The materials have remarkably low thermal conductivity, the lowest thermal conductivity was found to be 0.7 W/（m.K） in the sample with the ratio of Bi2Te3：Sb2Te3 of 1：1. Improved thermoelectric properties could be expected by the doping optimization of the composites.