熔体旋甩n型Bi_2Te_3基料微结构和电传输性能

Microstructure and Electrical Transport Properities of n-type Bismuth Telluride Based Compounds Prepared by Melt Spinning Technique

采用熔体旋甩(MS)结合放电等离子体烧结法(SPS),制备了具有层状纳米结构的n型Bi2Te3基热电材料。对薄带和SPS烧结后块体材料的相组成和微结构进行了分析和表征,在300—420 K的温度范围内测量了电导率(σ)和Seebeck系数(α)。结果表明:得到的带状产物接触面是等轴状晶粒而自由面是枝状晶,铜辊转速从10 m/s增加到30 m/s时带状产物接触面和自由面的等轴状及枝状晶的尺寸明显减小,烧结块体的晶粒尺寸及层状厚度也明显减小,材料功率因子在300 K从1.7×10-3W/(mK2)增大到了3.1×10-3W/(mK2)。

N-type bismuth telluride based compounds with layered nano-structure are prepared by combining melt spinning （MS） technique with spark plasma sintering （SPS）. The phase structure and the microstructure of the ribbons prepared by MS and the bulk samples obtained by SPS are investigated. Electrical conductivity （ σ ） and Seebeck coefficient （ α ） of bulk materials are measured in the temperature range of 300-420 K. The contact surface of melt-spinning ribbons consists of equaled grains, while the free surface consists of dendritic grains. When the linear speed of copper roller increases from 10 m/s to 30 m/s, equaled grains of contact surface and the dendritic grains of free surface become small, the sizes of grain and layered structure of the SPS sample significantly reduce, and power factor of the corresponding bulk sample increases from 1.7 × 10^-3 W/（mK2） to 3.1× 10^-3 W/（mK^2） at 300 K.