High performance of Mg_(3)Bi_(1.5)Sb_(0.5) based materials for power generation:Revealing the counter-intuitive effect of tuning Bi content on the thermoelectric properties  

作　　者：Nuo Qu Yuke Zhu Jianbo Zhu Kuai Yu Fengkai Guo Zihang Liu Qian Zhang Wei Cai Jiehe Sui 

机构地区：[1]State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,Harbin 150001,China [2]School of Materials Science and Engineering,Harbin Institute of Technology,Harbin,150001,China [3]Department of Materials Science and Engineering,Harbin Institute of Technology,Shenzhen 518055,China

出　　处：《Journal of Magnesium and Alloys》2024年第11期4538-4546,共9页镁合金学报(英文)

基　　金：National Natural Science Foundation of China(Nos.52130106);Heilongjiang Touyan Innovation Team Program;Fundamental Research Funds for the Central Universities(FRFCU5710053021 and HIT.OCEF.2021014)。

摘　　要：Recently,Mg_(3)Sb_(2)-xBixalloys have attracted intensive attention,with the aim of maximizing the electrical transport performance via donor element doping,increasing the grain size,as well as electronic band structure engineering.However,less attention has been paid to other significant factors,like how these intrinsic point defects and accompanied secondary phases influence thermoelectric properties.In this study,the microstructure and thermoelectric transport properties of Mg_(3.2)Sb_(0.5)Bi_(1.495-x)Te_(0.005)(x=0~0.2)compounds were systematically investigated,where tuning the Bi content shows the counter-intuitive impact on the thermoelectric properties.It was found that the Bipoor environment associated with Bi impurities facilitated the increment of cation vacancy formation energy and then increased the carrier concentration,leading to the enhancement of power factor.Simultaneously,the reduction of Bi-rich second phase content weakened the carrier scattering by grain boundaries whereas high carrier mobility was maintained.Moreover,the bipolar thermal conductivity decreased obviously due to the increased majority carrier concentration to suppress the intrinsic excitation.The synergistic optimization pushes the average ZT value(300-573 K)up to 0.95 in the Mg_(3.2)Sb_(0.5)Bi_(1.295)Te_(0.005)sample.Moreover,the calculated single-leg conversion efficiency is increased up to 9.7%with the hot-side temperature of 573 K,as the record-high value in this system.

关 键 词：Mg_(3)Sb_(2)-xBix alloys Nanoscale Bi-rich phase Bipolar thermal conductivity Thermoelectric performance 

分 类 号：TG146.22[一般工业技术—材料科学与工程]