Enhancing thermoelectric performance in P-type Mg_(3)Sb_(2)-based Zintls through optimization of band gap structure and nanostructuring  

作　　者：Yi-bo Zhang Ji-Sheng Liang Chengyan Liu Qi Zhou Zhe Xu Hong-bo Chen Fu-cong Li Ying Peng Lei Miao 

机构地区：[1]Guangxi Key Laboratory of Information Material,Engineering Research Center of Electronic Information Materials and Devices,Ministry of Education,School of Material Science and Engineering,Guilin University of Electronic Technology,Guilin 541004,China [2]Guangxi Key Laboratory for Relativity Astrophysics,Center on Nanoenergy Research,Guangxi Key Laboratory of Processing for Nonferrous Metal and Featured Materials,School of Physical Science&Technology,Guangxi University,Nanning 530004,China [3]Guangxi Key Laboratory of Precision Navigation Technology and Application,Guilin University of Electronic Technology,School of Information and Communication,Guilin 541004,China

出　　处：《Journal of Materials Science & Technology》2024年第3期25-32,共8页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.U21A2054,52273285,52061009,52262032);the National Key Research and Development Program of China(No.2022YFE0119100);the Guangxi Science and Technology Planning Project(Grant No.AD21220056).

摘　　要：P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relatively low TE performance,limiting their application in TE devices.In this work,we simultaneously introduce Bi alloying at Sb sites and Ag doping at Mg sites into the Mg_(3)Sb_(2)to coopera-tively optimize the electrical and thermal properties for the first time,acquiring the highest ZT value of∼0.85 at 723 K and a high average ZT of 0.39 in the temperature range of 323-723 K in sample Mg_(2.94)Ag_(0.06)Sb_(1.9)Bi_(0.1).The first-principle calculations show that the codoping of Ag and Bi can shift the Fermi level into the valence band and narrow the band gap,resulting in the increased carrier concentration from 3.50×10^(17)cm^(-3)in the reference Mg 3 Sb 0.9 Bi 0.1 to∼7.88×10^(19)cm^(-3)in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.As a result,a remarkable power factor of∼778.9μW m^(-1)K^(-2)at 723 K is achieved in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.Meanwhile,a low lattice thermal conductivity of∼0.48 W m^(-1)K^(-1)at 723 K is also obtained with the help of phonon scattering at the distorted lattice,point defects,and nano-precipitates in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.The synergistic effect of using the multi-element co-doping/-alloying to optimize electrical properties in Mg_(3)Sb_(2)holds promise for further improving the TE performance of Zintl phase materials or even others.

关 键 词：Thermoelectric materials Band engineering Nanostructuring P-type Mg_(3)Sb_(2) Ag and Bi Co-doping 

分 类 号：TG1[金属学及工艺—金属学]