中国物理B ›› 2012, Vol. 21 ›› Issue (5): 56301-056301.doi: 10.1088/1674-1056/21/5/056301

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First-principles investigation on the elastic stability and thermodynamic properties of Ti2SC

杨则金1,郭云东2,令狐荣锋3,程新路4,杨向东4   

  1. 1. School of Science, Zhejiang University of Technology, Hangzhou 310023, China;
    2. School of Physics, Neijiang Normal University, Neijiang 641112, China;
    3. School of Physics, Guizhou Normal College, Guiyang 550018, China;
    4. Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
  • 收稿日期:2011-11-15 修回日期:2012-04-27 出版日期:2012-04-01 发布日期:2012-04-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 10974139, 10964002, 11104247, and 11176020), the Natural Science Foundation of Guizhou Province, China (Grant Nos. [2009]2066 and [2009]07), the Project of Aiding Elites' Research Condition of Guizhou Province, China (Grant No. TZJF-2008-42), and the Science Foundation from Education Ministry of Zhejiang Province, China (Grant No. Y201121807).

First-principles investigation on the elastic stability and thermodynamic properties of Ti2SC

Yang Ze-Jin(杨则金)a)†, Guo Yun-Dong(郭云东)b), Linghu Rong-Feng(令狐荣锋)c), Cheng Xin-Lu(程新路)d), and Yang Xiang-Dong(杨向东)d)   

  1. a. School of Science, Zhejiang University of Technology, Hangzhou 310023, China;
    b. School of Physics, Neijiang Normal University, Neijiang 641112, China;
    c. School of Physics, Guizhou Normal College, Guiyang 550018, China;
    d. Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
  • Received:2011-11-15 Revised:2012-04-27 Online:2012-04-01 Published:2012-04-01
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 10974139, 10964002, 11104247, and 11176020), the Natural Science Foundation of Guizhou Province, China (Grant Nos. [2009]2066 and [2009]07), the Project of Aiding Elites' Research Condition of Guizhou Province, China (Grant No. TZJF-2008-42), and the Science Foundation from Education Ministry of Zhejiang Province, China (Grant No. Y201121807).

摘要: Using Vanderbilt-type plane-wave ultrasoft pseudopotentials within the generalized gradient approximation (GGA) in the frame of density functional theory (DFT), we have investigated the crystal structures, elastic, and thermodynamic properties for Ti2SC under high temperature and high pressure. The calculated pressure dependence of the lattice volume is in excellent agreement with the experimental results. The calculated structural parameter of the Ti atom experienced a subtle increase with applied pressures and the increase suspended under higher pressures. The elastic constants calculations demonstrated that the crystal lattice is still stable up to 200 GPa. Investigations on the elastic properties show that the c axis is stiffer than the a axis, which is consistent with the larger longitudinal elastic constants (C33, C11) relative to transverse ones (C44, C12, C13). Study on Poisson's ratio confirmed that the higher ionic or weaker covalent contribution in intra-atomic bonding for Ti2SC should be assumed and the nature of ionic increased with pressure. The ratio (B/G) of bulk (B) and shear (G) moduli as well as B/C44 demonstrated the brittleness of Ti2SC at ambient conditions and the brittleness decreased with pressure. Moreover, the isothermal and adiabatic bulk moduli displayed opposite temperature dependence under different pressures. Again, we observed that the Debye temperature and Gr黱eisen parameter show weak temperature dependence relative to the thermal expansion coefficient, entropy, and heat capacity, from which the pressure effects are clearly seen.

关键词: first-principles, elasticity, thermodynamic properties, Ti2SC

Abstract: Using Vanderbilt-type plane-wave ultrasoft pseudopotentials within the generalized gradient approximation (GGA) in the frame of density functional theory (DFT), we have investigated the crystal structures, elastic, and thermodynamic properties for Ti2SC under high temperature and high pressure. The calculated pressure dependence of the lattice volume is in excellent agreement with the experimental results. The calculated structural parameter of the Ti atom experienced a subtle increase with applied pressures and the increase suspended under higher pressures. The elastic constants calculations demonstrated that the crystal lattice is still stable up to 200 GPa. Investigations on the elastic properties show that the c axis is stiffer than the a axis, which is consistent with the larger longitudinal elastic constants (C33, C11) relative to transverse ones (C44, C12, C13). Study on Poisson's ratio confirmed that the higher ionic or weaker covalent contribution in intra-atomic bonding for Ti2SC should be assumed and the nature of ionic increased with pressure. The ratio (B/G) of bulk (B) and shear (G) moduli as well as B/C44 demonstrated the brittleness of Ti2SC at ambient conditions and the brittleness decreased with pressure. Moreover, the isothermal and adiabatic bulk moduli displayed opposite temperature dependence under different pressures. Again, we observed that the Debye temperature and Grüneisen parameter show weak temperature dependence relative to the thermal expansion coefficient, entropy, and heat capacity, from which the pressure effects are clearly seen.

Key words: first-principles, elasticity, thermodynamic properties, Ti2SC

中图分类号:  (First-principles theory)

  • 63.20.dk
62.20.D- (Elasticity) 65.40.-b (Thermal properties of crystalline solids)