中国物理B ›› 2023, Vol. 32 ›› Issue (1): 16101-016101.doi: 10.1088/1674-1056/ac6db5

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Pressure-induced stable structures and physical properties of Sr-Ge system

Shuai Han(韩帅)1, Shuai Duan(段帅)1, Yun-Xian Liu(刘云仙)1,2,†, Chao Wang(王超)1,2, Xin Chen(陈欣)1,2, Hai-Rui Sun(孙海瑞)1,2, and Xiao-Bing Liu(刘晓兵)1,2,‡   

  1. 1 Laboratory of High Pressure Physics and Material Science, School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China;
    2 Advanced Research Institute of Multidisciplinary Sciences, Qufu Normal University, Qufu 273165, China
  • 收稿日期:2022-03-24 修回日期:2022-04-19 接受日期:2022-05-07 出版日期:2022-12-08 发布日期:2022-12-27
  • 通讯作者: Yun-Xian Liu, Xiao-Bing Liu E-mail:yunxianliu1988@163.com;xiaobing.phy@qfnu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 52102335, 11704220, 11804184, 11974208, and 11804185) and the Shandong Provincial Natural Science Foundation, China (Grant Nos. ZR2021MA050, ZR2017BA020, ZR2018PA010, ZR2019MA054, and ZR2017BA012).

Pressure-induced stable structures and physical properties of Sr-Ge system

Shuai Han(韩帅)1, Shuai Duan(段帅)1, Yun-Xian Liu(刘云仙)1,2,†, Chao Wang(王超)1,2, Xin Chen(陈欣)1,2, Hai-Rui Sun(孙海瑞)1,2, and Xiao-Bing Liu(刘晓兵)1,2,‡   

  1. 1 Laboratory of High Pressure Physics and Material Science, School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China;
    2 Advanced Research Institute of Multidisciplinary Sciences, Qufu Normal University, Qufu 273165, China
  • Received:2022-03-24 Revised:2022-04-19 Accepted:2022-05-07 Online:2022-12-08 Published:2022-12-27
  • Contact: Yun-Xian Liu, Xiao-Bing Liu E-mail:yunxianliu1988@163.com;xiaobing.phy@qfnu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 52102335, 11704220, 11804184, 11974208, and 11804185) and the Shandong Provincial Natural Science Foundation, China (Grant Nos. ZR2021MA050, ZR2017BA020, ZR2018PA010, ZR2019MA054, and ZR2017BA012).

摘要: We have systematically investigated the structures of Sr-Ge system under pressures up to 200 GPa and found six stable stoichiometric structures, they being Sr$_{3}$Ge, Sr$_{2}$Ge, SrGe, SrGe$_{2}$, SrGe$_{3}$, and SrGe$_{4}$. We demonstrate the interesting structure evolution behaviors in Sr-Ge system with the increase of germanium content, Ge atoms arranging into isolated anions in Sr$_{3}$Ge, chains in Sr$_{2}$Ge, square units in SrGe, trigonal units and hexahedrons in SrGe$_{2}$, cages in SrGe$_{3}$, hexagons and Ge$_{8}$ rings in SrGe$_{4}$. The structural diversity produces various manifestations of electronic structures, which is of benefit to electrical transportation. Among them, these novel phases with metallic structures show superconductivity (maximum $T_{\rm c}\sim 8.94$ K for Pmmn Sr$_{3}$Ge). Notably, the n-type semiconducting Pnma SrGe$_{2}$ structure exhibits high Seebeck coefficient and excellent electrical conductivity along the $y$ direction, leading to a high $ZT$ value up to 1.55 at 500 K, which can be potential candidates as high-performance thermoelectrics. Our results will enable the development of fundamental science in condensed matter physics and potential applications in novel electronics or thermoelectric materials.

关键词: high pressure, first-principle calculation, germanium-strontium compounds, superconductivity, thermoelectric property

Abstract: We have systematically investigated the structures of Sr-Ge system under pressures up to 200 GPa and found six stable stoichiometric structures, they being Sr$_{3}$Ge, Sr$_{2}$Ge, SrGe, SrGe$_{2}$, SrGe$_{3}$, and SrGe$_{4}$. We demonstrate the interesting structure evolution behaviors in Sr-Ge system with the increase of germanium content, Ge atoms arranging into isolated anions in Sr$_{3}$Ge, chains in Sr$_{2}$Ge, square units in SrGe, trigonal units and hexahedrons in SrGe$_{2}$, cages in SrGe$_{3}$, hexagons and Ge$_{8}$ rings in SrGe$_{4}$. The structural diversity produces various manifestations of electronic structures, which is of benefit to electrical transportation. Among them, these novel phases with metallic structures show superconductivity (maximum $T_{\rm c}\sim 8.94$ K for Pmmn Sr$_{3}$Ge). Notably, the n-type semiconducting Pnma SrGe$_{2}$ structure exhibits high Seebeck coefficient and excellent electrical conductivity along the $y$ direction, leading to a high $ZT$ value up to 1.55 at 500 K, which can be potential candidates as high-performance thermoelectrics. Our results will enable the development of fundamental science in condensed matter physics and potential applications in novel electronics or thermoelectric materials.

Key words: high pressure, first-principle calculation, germanium-strontium compounds, superconductivity, thermoelectric property

中图分类号:  (Crystallographic aspects of phase transformations; pressure effects)

  • 61.50.Ks
62.50.-p (High-pressure effects in solids and liquids) 63.20.dk (First-principles theory) 71.20.-b (Electron density of states and band structure of crystalline solids)