Achieving High Thermoelectric Performance in Rare-Earth Element-Free CaMg_(2)Bi_(2) with High Carrier Mobility and Ultralow Lattice Thermal Conductivity

作     者：Muchun Guo Fengkai Guo Jianbo Zhu Li Yin Qian Zhang Wei Cai Jiehe Sui 

作者机构：National Key Laboratory for Precision Hot Processing of MetalsHarbin Institute of TechnologyHarbin 150001China Department of Materials Science and EngineeringHarbin Institute of TechnologyShenzhenGuangdong 518055China 

出 版 物：《Research》 (研究（英文）)

年 卷 期：2020年第2020卷第1期

页      面：824-833页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学] 070301[理学-无机化学] 

基　　金：This work was supported by the National Natural Science Foundation of China(Nos.51771065 and 51871082) 

主　　题：alloying substitution Rare 

摘      要：CaMg_(2)Bi_(2)-based compounds,a kind of the representative compounds of Zintl phases,have uniquely inherent layered structure and hence are considered to be potential thermoelectric ***,alloying is a traditional and effective way to reduce the lattice thermal conductivity through the mass and strain field fluctuation between host and guest *** cation sites have very few contributions to the band structure around the fermi level;thus,cation substitution may have negligible influence on the electric transport *** is more,widespread application of thermoelectric materials not only desires high ZT value but also calls for low-cost and environmentally benign constituent ***,Ba substitution on cation site achieves a sharp reduction in lattice thermal conductivity through enhanced point defects scattering without the obvious sacrifice of high carrier mobility,and thus improves thermoelectric ***,by combining further enhanced phonon scattering caused by isoelectronic substitution of Zn on the Mg site,an extraordinarily low lattice thermal conductivity of 0.51Wm^(-1) K^(-1) at 873 K is achieved in(Ca_(0.75)Ba_(0.25))_(0.995)Na_(0.005)Mg_(1.95)Zn_(0.05)Bi_(1.98) alloy,approaching the amorphous *** maintenance of high mobility and realization of ultralow lattice thermal conductivity synergistically result in broadly improvement of the quality factorβ.Finally,a maximum ZT of 1.25 at 873K and the corresponding ZTave up to 0.85 from 300 K to 873K have been obtained for the same composition,meanwhile possessing temperature independent compatibility *** our knowledge,the current ZTave exceeds all the reported values in AMg_(2)Bi_(2)-based compounds so ***,the low-cost and environmentfriendly characteristic plus excellent thermoelectric performance also make the present Zintl phase CaMg_(2)Bi_(2) more competitive in practical application.