n-Type Nanostructured Thermoelectric Materials Prepared from Chemically Synthesized Ultrathin Bi2Te3 Nanoplates
n-Type Nanostructured Thermoelectric Materials Prepared from Chemically Synthesized Ultrathin Bi2Te3 Nanoplates
复制标题
DOI：
10.1021/nl203389x
复制
发表时间：
2012-02-01
期刊：
影响因子：
10.8
通讯作者：
Hyeon, Taeghwan
中科院分区：
文献类型：
--
作者：
Son, Jae Sung;Choi, Moon Kee;Hyeon, Taeghwan
在这里，我们报道了大规模合成超薄Bi2Te3纳米板和随后的放电等离子烧结制备n型纳米结构块体热电材料。用硫化铋与三正辛基碲化膦在油胺中反应合成了Bi2Te3纳米片。纳米板的厚度约为1 nm，相当于Bi2Te3晶体中的单层。采用放电等离子烧结技术对去除表面活性剂的Bi2Te3纳米板进行烧结，制备了Bi2Te3纳米块体材料。研究发现，烧结温度对Bi2Te3纳米块体材料的热电性能有很大的影响，烧结温度对Bi2Te3纳米块体材料的热电性能有很大的影响。电导率随着烧结温度的升高而增加，这是由于晶粒长大和致密化导致界面密度降低所致。随着烧结温度的升高，Seebeck系数大致减小。有趣的是，电子浓度和迁移率强烈依赖于烧结温度，这表明界面处存在势垒散射以及缺陷和有机残留物的掺杂效应。由于晶粒长大和致密化，材料的热导率也随着烧结温度的升高而增加。最大热电优值ZT在400K时为0.62，是以化学合成纳米颗粒为基础的n型纳米结构材料中最高的数值之一。这种ZT的增加显示了通过化学合成来制备高效热电材料的可能性。
We herein report on the large-scale synthesis of ultrathin Bi2Te3 nanoplates and subsequent spark plasma sintering to fabricate n-type nanostructured bulk thermoelectric materials. Bi2Te3 nanoplates were synthesized by the reaction between bismuth thiolate and tri-n-octylphosphine telluride in oleylamine. The thickness of the nanoplates was similar to 1 nm, which corresponds to a single layer in Bi2Te3 crystals. Bi2Te3 nanostructured bulk materials were prepared by sintering of surfactant-removed Bi2Te3 nanoplates using spark plasma sintering. We found that the grain size and density were strongly dependent on the sintering temperature, and we investigated the effect of the sintering temperature on the thermoelectric properties of the Bi2Te3 nanostructured bulk materials. The electrical conductivities increased with an increase in the sintering temperature, owing to the decreased interface density arising from the grain growth and densification. The Seebeck coefficients roughly decreased with an increase in the sintering temperature. Interestingly, the electron concentrations and mobilities strongly depended on the sintering temperature, suggesting the potential barrier scattering at interfaces and the doping effect of defects and organic residues. The thermal conductivities also increased with an increase in the sintering temperature because of grain growth and densification. The maximum thermoelectric figure-of-merit, ZT, is 0.62 at 400 K, which is one of the highest among the reported values of n-type nanostructured materials based on chemically synthesized nanoparticles. This increase in ZT shows the possibility of the preparation of highly efficient thermoelectric materials by chemical synthesis.