微波热压优化分层微观结构BixSb2−xTe3合金的热电性能

Thermoelectric properties of BixSb2−xTe3 alloy with layered microstructure optimized by microwave hot pressing

通过机械合金化结合微波活化热压新技术(MAHP)制备分层结构的p型BixSb2−xTe3(x=0.30,0.35和0.40,质量分数)合金,研究Bi含量对BixSb2−xTe3合金组织与热电性能的影响。结果表明,合金中存在不规则纳米颗粒,为原位纳米结构,是由微波电弧效应引起的。随Bi含量增加,载流子浓度明显降低,使得电阻率和塞贝克系数增加。同时,由于不规则纳米颗粒减少,合金的晶格热导率增加。Bi0.3Sb1.7Te3具有最大功率因子3.81 mW/(m·K^2)和最小晶格热导率0.33 W/(m·K),从而在70℃时获得最大的无量纲热电优值1.23。本研究引入的MAHP技术具有明显提升BixSb2−xTe3合金热电性能的效果。

The p-type BixSb2-xTe3 alloys with hierarchical microstructures were prepared by mechanical alloying and a new sintering technique of microwave activated hot pressing(MAHP).The effects of Bi content on the microstructure and thermoelectric properties of BixSb2−xTe3 alloy were studied.The results show that there are irregular nanoparticles,which are in-situ nanostructures caused by microwave arc effect.With increasing Bi content,the electrical resistivity and Seebeck coefficient increase due to the obvious decrease of carrier concentration.At the same time,the lattice thermal conductivity increases due to the decrease in the amount of irregular nanograins.BixSb2−xTe3 has a maximum power factor of 3.81 mW/(m·K^2)and a minimum lattice thermal conductivity of 0.33 W/(m·K),so as to obtain the maximum dimensionless figure of merit value of 1.23 at 70℃.The MAHP technique introduced in this work has achieved a significant improvement in the thermoelectric properties of the BixSb2−xTe3 alloy.