Vacancies tailoring lattice anharmonicity of Zintl-type thermoelectrics

Jinfeng Zhu; Qingyong Ren; Chen Chen; Chen Wang; Mingfang Shu; Miao He; Cuiping Zhang; Manh Duc Le; Shuki Torri; Chin-Wei Wang; Jianli Wang; Zhenxiang Cheng; Lisi Li; Guohua Wang; Yuxuan Jiang; Mingzai Wu; Zhe Qu; Xin Tong; Yue Chen; Qian Zhang; Jie Ma

doi:10.1038/s41467-024-46895-4

Vacancies tailoring lattice anharmonicity of Zintl-type thermoelectrics

Nat Commun. 2024 Mar 23;15(1):2618. doi: 10.1038/s41467-024-46895-4.

Authors

Jinfeng Zhu^#¹, Qingyong Ren^#^{2

3

4}, Chen Chen^#^{5

6}, Chen Wang⁷, Mingfang Shu¹, Miao He^{8

9}, Cuiping Zhang¹, Manh Duc Le¹⁰, Shuki Torri¹¹, Chin-Wei Wang¹², Jianli Wang^{13

14}, Zhenxiang Cheng¹⁴, Lisi Li^{15

16

17}, Guohua Wang¹, Yuxuan Jiang¹⁸, Mingzai Wu¹⁸, Zhe Qu^{8

9}, Xin Tong^{19

20

21}, Yue Chen²², Qian Zhang^{23

24}, Jie Ma^{25

26}

Affiliations

¹ Key Laboratory of Artificial Structures and Quantum Control, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
² Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China. renqy@ihep.ac.cn.
³ Spallation Neutron Source Science Center, Dongguan, China. renqy@ihep.ac.cn.
⁴ Guangdong Provincial Key Laboratory of Extreme Conditions, Dongguan, China. renqy@ihep.ac.cn.
⁵ School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, China.
⁶ School of Physical Sciences, Great Bay University, Dongguan, Guangdong, China.
⁷ Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China.
⁸ Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, CAS Key Laboratory of Photovoltaic and Energy Conservation Materials, High Magnetic Field Laboratory of Chinese Academy of Sciences (CHMFL), HFIPS, CAS, Hefei, China.
⁹ Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, China.
¹⁰ ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, England, UK.
¹¹ Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tokai, Ibaraki, Japan.
¹² Neutron Group, National Synchrotron Radiation Research Center, Hsinchu, Taiwan.
¹³ College of Physics, Jilin University, Changchun, China.
¹⁴ Institute for Superconducting and Electronic Materials, Faculty of Engineering and Information Sciences, University of Wollongong, Innovation Campus, North Wollongong, Australia.
¹⁵ Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
¹⁶ Spallation Neutron Source Science Center, Dongguan, China.
¹⁷ Guangdong Provincial Key Laboratory of Extreme Conditions, Dongguan, China.
¹⁸ School of Physics and Optoelectronics Engineering, Anhui University, Hefei, Anhui, China.
¹⁹ Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China. tongxin@ihep.ac.cn.
²⁰ Spallation Neutron Source Science Center, Dongguan, China. tongxin@ihep.ac.cn.
²¹ Guangdong Provincial Key Laboratory of Extreme Conditions, Dongguan, China. tongxin@ihep.ac.cn.
²² Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China. yuechen@hku.hk.
²³ School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, China. zhangqf@hit.edu.cn.
²⁴ State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, China. zhangqf@hit.edu.cn.
²⁵ Key Laboratory of Artificial Structures and Quantum Control, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China. jma3@sjtu.edu.cn.
²⁶ Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, Jiangsu, China. jma3@sjtu.edu.cn.

^# Contributed equally.

Abstract

While phonon anharmonicity affects lattice thermal conductivity intrinsically and is difficult to be modified, controllable lattice defects routinely function only by scattering phonons extrinsically. Here, through a comprehensive study of crystal structure and lattice dynamics of Zintl-type Sr(Cu,Ag,Zn)Sb thermoelectric compounds using neutron scattering techniques and theoretical simulations, we show that the role of vacancies in suppressing lattice thermal conductivity could extend beyond defect scattering. The vacancies in Sr₂ZnSb₂ significantly enhance lattice anharmonicity, causing a giant softening and broadening of the entire phonon spectrum and, together with defect scattering, leading to a ~ 86% decrease in the maximum lattice thermal conductivity compared to SrCuSb. We show that this huge lattice change arises from charge density reconstruction, which undermines both interlayer and intralayer atomic bonding strength in the hierarchical structure. These microscopic insights demonstrate a promise of artificially tailoring phonon anharmonicity through lattice defect engineering to manipulate lattice thermal conductivity in the design of energy conversion materials.