中国物理B ›› 2017, Vol. 26 ›› Issue (2): 26501-026501.doi: 10.1088/1674-1056/26/2/026501

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

Anomalous low-temperature heat capacity in antiperovskite compounds

Xin-Ge Guo(郭新格), Jian-Chao Lin(林建超), Peng Tong(童鹏), Shuai Lin(蔺帅), Cheng Yang(杨骋), Wen-Jian Lu(鲁文建), Wen-Hai Song(宋文海), Yu-Ping Sun(孙玉平)   

  1. 1 Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China;
    2 University of Science and Technology of China, Hefei 230026, China;
    3 High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China;
    4 Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
  • 收稿日期:2016-09-19 修回日期:2016-11-04 出版日期:2017-02-05 发布日期:2017-02-05
  • 通讯作者: Peng Tong E-mail:tongpeng@issp.ac.cn
  • 基金资助:

    Project supported by the National Key Basic Research Program of China (Grant Nos. 2011CBA00111) and the National Natural Science Foundation of China (Grant Nos. 51322105, U1632158, 51301165, and 51301167).

Anomalous low-temperature heat capacity in antiperovskite compounds

Xin-Ge Guo(郭新格)1,2, Jian-Chao Lin(林建超)1, Peng Tong(童鹏)1, Shuai Lin(蔺帅)1, Cheng Yang(杨骋)1, Wen-Jian Lu(鲁文建)1, Wen-Hai Song(宋文海)1, Yu-Ping Sun(孙玉平)1,3,4   

  1. 1 Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China;
    2 University of Science and Technology of China, Hefei 230026, China;
    3 High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China;
    4 Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
  • Received:2016-09-19 Revised:2016-11-04 Online:2017-02-05 Published:2017-02-05
  • Contact: Peng Tong E-mail:tongpeng@issp.ac.cn
  • Supported by:

    Project supported by the National Key Basic Research Program of China (Grant Nos. 2011CBA00111) and the National Natural Science Foundation of China (Grant Nos. 51322105, U1632158, 51301165, and 51301167).

摘要:

The low-temperature heat capacities are studied for antiperovskite compounds AXM3 (A=Al, Ga, Cu, Ag, Sn, X=C, N, M=Mn, Fe, Co). A large peak in (C-γT)/T3 versus T is observed for each of a total of 18 compounds investigated, indicating an existence of low-energy phonon mode unexpected by Debye T3 law. Such a peak is insensitive to the external magnetic field up to 80 kOe (1 Oe=79.5775 A·m-1). For compounds with smaller lattice constant, the peak shifts towards higher temperatures with a reduction of peak height. This abnormal peak in (C-γT)/T3 versus T of antiperovskite compound may result from the strongly dispersive acoustic branch due to the heavier A atoms and the optical-like mode from the dynamic rotation of XM6 octahedron. Such a low-energy phonon mode may not contribute negatively to the normal thermal expansion in AXM3 compounds, while it is usually concomitant with negative thermal expansion in open-structure material (e.g., ZrW2O8, ScF3).

关键词: low-temperature heat capacity, low-energy phonon modes, antiperovskite compound, negative thermal expansion

Abstract:

The low-temperature heat capacities are studied for antiperovskite compounds AXM3 (A=Al, Ga, Cu, Ag, Sn, X=C, N, M=Mn, Fe, Co). A large peak in (C-γT)/T3 versus T is observed for each of a total of 18 compounds investigated, indicating an existence of low-energy phonon mode unexpected by Debye T3 law. Such a peak is insensitive to the external magnetic field up to 80 kOe (1 Oe=79.5775 A·m-1). For compounds with smaller lattice constant, the peak shifts towards higher temperatures with a reduction of peak height. This abnormal peak in (C-γT)/T3 versus T of antiperovskite compound may result from the strongly dispersive acoustic branch due to the heavier A atoms and the optical-like mode from the dynamic rotation of XM6 octahedron. Such a low-energy phonon mode may not contribute negatively to the normal thermal expansion in AXM3 compounds, while it is usually concomitant with negative thermal expansion in open-structure material (e.g., ZrW2O8, ScF3).

Key words: low-temperature heat capacity, low-energy phonon modes, antiperovskite compound, negative thermal expansion

中图分类号:  (Heat capacity)

  • 65.40.Ba
65.40.De (Thermal expansion; thermomechanical effects) 75.20.En (Metals and alloys)