急冷甩带对Bi_2Te_(2.7)Se_(0.3)热电材料微观结构与电性能的影响

Effects of Melt Spinning Process on Microstructure and Electrical Properties of Bi_2Te_(2.7)Se_(0.3) Thermoelectric Material

采用急冷甩带法和放电等离子体烧结(SPS)制备得到了块体Bi2Te2.7Se0.3热电材料,在室温下测量其热电性能,Seebeck系数最高达到-139.33μV.K-1,功率因子也有所提高,最大值1.71×103W.m-.1K-2,计算得到最大热电优值0.421。材料经急冷甩带后,微观组织结构发生变化,内部缺陷增多,晶粒细化,改变了载流子的散射机制,增强了声子散射。虽然电导率有一定程度减小,但Seebeck系数增大,热导率减小,提高了热电性能。

Bulk Bi2Te2.7Se0.3 thermoelectric materials were prepared by combining melt spinning technique with spark plasma sintering. Thermoelectric properties were investigated at room temperature, the Seebeck co- efficient was increased by -139.33μV·K-1 , and the power factor was improved by 1.71×10^3w·m-1·K-2. The calculated maximum figure of merit was ZT = 0. 421. The microstructure study showed that the ob- tained microstructure had small grains and big defects which was very different from those obtained by normal cooling, these led to dispersion change of the carrier, and increase of the scatter of phonon.