MWCNTs_X/Bi₂(Te_0.95Se_0.05)₃复合热电材料的制备及特性研究

Preparation and Properties of MWCNTs_X/Bi₂(Te_0.95Se_0.05)₃ Composite Thermoelectric Material

本文采用热压烧结法,通过在N型Bi2(Te0.95Se0.05)3热电材料中掺杂少量的多壁碳纳米管(MWCNTs),制备出了不同掺杂比例的MWCNTsX/Bi2(Te0.95Se0.05)3复合热电材料。利用X射线衍射仪、扫描电镜及热电特性分析装置等设备,对制备样品的微结构、形貌及热电特性等进行了分析。结果发现,少量MWNCTs的掺杂并未改变MWCNTsX/Bi2(Te0.95Se0.05)3复合热电材料的晶格结构,同时,少量掺杂还可在复合热电材料微结构中产生适量的晶界和生长缺陷。并且,均匀分散的MWNCTs还形成了三维导电通道,可显著增强晶格对声子和低能电子的散射,提升了材料的电导率,降低了其热导率。但对比研究也发现,过多MWNCTs的掺杂反而不利于MWCNTsX/Bi2(Te0.95Se0.05)3复合热电材料热电特性的提升。测试表明,在温度为T = 316 K时,掺杂MWNCTs质量比为x = 0.003的复合材料样品具有最大的ZT值,约为1.39,这比未掺杂的Bi2(Te0.95Se0.05)3样品的最大ZT值0.93提高了近50%。论文研究结果对进一步提升Bi2Te3类热电材料的热电优值,拓展其商业化应用范围提供了新的思路。

In this paper, the MWCNTsX/Bi2(Te0.95Se0.05)3 composite thermoe-lectric materials were prepared by doping a small amount of MWCNTs in the N-type Bi2(Te0.95Se0.05)3 thermoelectric materials with different MWCNTs mass ratio by hot-pressing sintering method in the special mould. The crystal microstructure, surface morphology and thermoelectric parameters of the fabricated samples were analyzed by XRD, SEM, and thermoelectric performance testing equipment, etc. It was found that the lattice structure of the synthesized MWCNTsX/Bi2(Te0.95Se0.05)3 composite samples was not changed by doping a small amount of MWNCTs. However, doping with a small amount of homogeneous dispersion MWNCTs can produce a moderate amount of grain boundaries, growth defects and three-dimensional conductive channels of MWNCTs in the microstructure of composite, which can increase the scattering effect of phonons and low energy electrons in the lattice, effectively enhance the conductivity, and reduce thermal conductivity of the composite samples. But it was also found that excessive MWNCTs doping is not conducive to the improvement of thermoelec-tric properties of MWCNTsX/Bi2(Te0.95Se0.05)3 composite samples. As x = 0.003, the prepared MWCNTsX/ Bi2(Te0.95Se0.05)3 composite thermoelectric sam-ples exhibited the maximum dimensionless figure of merit (ZT) of 1.39, which is nearly 50% higher than that of the undoped Bi2(Te0.95Se0.05)3 sam-ple with the maximum ZT value of 0.93 at T = 316 K. The results in this paper can provide a new re-searching method to improve the ZT value of the Bi2Te3-based thermoelectric materials and expand their commercial application range.