Ag rearrangement induced metal-insulator phase transition in thermoelectric MgAgSb

Zhang，Zhou1; Zhu，Yifan2; Ji，Jialin1; Zhang，Jianxin1; Luo，Huifang1; Fu，Chenguang3; Li，Qianqian1; Brod，Madison4; Snyder，G. Jeffrey4; Zhang，Yubo5; Yang，Jiong1,6; Zhang，Wenqing7,8

2022-07-01

10.1016/j.mtphys.2022.100702

Materials Today Physics   影响因子和分区

2542-5293

2542-5293

In recent years, materials with metal-to-insulator phase transitions have attracted great attention due to their property variations before and after the transition. As nearly all good thermoelectric materials are small band-gap semiconductors, a metal-insulator transition makes a profound difference in thermoelectric performance. Revealing the microscopic reasons for these variations is critical to understanding the structure-property relation in these materials. MgAgSb is an important thermoelectric material around room temperature, due to its high zT value and intrinsic low lattice thermal conductivity in the semiconducting α-phase. However, the thermoelectric properties of mid-temperature β-phase MgAgSb significantly deteriorate because the β-phase has no band gap. In this work, we reveal that the Ag atomic rearrangement between the two phases is the major reason responsible for the metal-insulator transition and deterioration of thermoelectric properties. In MgAgSb, there are strong interactions between Mg and Sb, as well as Ag and Sb, leading to bands of mixed character around the Fermi Level. In α-MgAgSb, the Mg–Sb bands in the conduction band minimum separate well with the bands around the valence band maximum, and form a finite band gap. Due to the Ag rearrangement and the formation of a quasi-two-dimensional structure of β-MgAgSb, the interactions among Mg–Ag–Sb atoms form multiple bands crossing the Fermi level, and realize the “two-dimensional metallization”. In addition, the structural variations in the β-phase results in higher phonon velocities and removal of additional low-frequency optical phonons as only shown in the α-phase, both of which leading to the relatively high κ of the β-phase. Our work provides new perspectives for the performance research and application of materials with metal-insulator phase transitions.

Atomic rearrangement Metal-insulator phase transition MgAgSb Structure-property relation

SCI ; EI

英语

其他

National Key Research and Development Program of China[2018YFB0703600];National Key Research and Development Program of China[2019YFA0704901];National Natural Science Foundation of China[52172216];National Natural Science Foundation of China[92163212];

Materials Science ; Physics

Materials Science, Multidisciplinary ; Physics, Applied

WOS:000797903100002

ELSEVIER

20221912100386

Atoms ; Deterioration ; Electronic structure ; Energy gap ; Fermi level ; Magnesium compounds ; Metal insulator boundaries ; Metal insulator transition ; Phonons ; Semiconductor insulator boundaries ; Silver ; Silver compounds ; Thermal conductivity ; Thermoelectric equipment

Precious Metals:547.1 ; Thermoelectric Energy:615.4 ; Thermodynamics:641.1 ; Electricity: Basic Concepts and Phenomena:701.1 ; Semiconductor Devices and Integrated Circuits:714.2 ; Atomic and Molecular Physics:931.3 ; Materials Science:951

2-s2.0-85129767732

Scopus

1.Materials Genome Institute,Shanghai University,Shanghai,200444,China
2.State Key Laboratory of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai,200050,China
3.State Key Laboratory of Silicon Materials and School of Materials Science and Engineering,Zhejiang University,Hangzhou,310027,China
4.Department of Materials Science and Engineering,Northwestern University,60208,United States
5.MinJiang Collaborative Center for Theoretical Physics,College of Physics and Electronic Information Engineering,Minjiang University,Fuzhou,350108,China
6.Zhejiang Laboratory,Hangzhou,Zhejiang,311100,China
7.Department of Materials Science and Engineering,And Shenzhen Institute for Quantum Science & Technology,Southern University of Science and Technology,Shenzhen,Guangdong,518055,China
8.Shenzhen Municipal Key-Lab for Advanced Quantum Materials and Devices,And Guangdong Provincial Key Lab for Computational Science and Materials Design,Southern University of Science and Technology,Shenzhen,Guangdong,518055,China

Zhang，Zhou,Zhu，Yifan,Ji，Jialin,et al. Ag rearrangement induced metal-insulator phase transition in thermoelectric MgAgSb[J]. Materials Today Physics,2022,25.

Zhang，Zhou.,Zhu，Yifan.,Ji，Jialin.,Zhang，Jianxin.,Luo，Huifang.,...&Zhang，Wenqing.(2022).Ag rearrangement induced metal-insulator phase transition in thermoelectric MgAgSb.Materials Today Physics,25.

Zhang，Zhou,et al."Ag rearrangement induced metal-insulator phase transition in thermoelectric MgAgSb".Materials Today Physics 25(2022).