中国物理B ›› 2012, Vol. 21 ›› Issue (8): 86103-086103.doi: 10.1088/1674-1056/21/8/086103

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

Pressure-induced structural transition and thermodynamic properties of RhN2 and effect of metallic bonding on its hardness

刘俊a, 邝小渝a, 王振华a, 黄肖芬b   

  1. a Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;
    b College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, China
  • 收稿日期:2011-10-14 修回日期:2011-12-26 出版日期:2012-07-01 发布日期:2012-07-01
  • 基金资助:
    Project supported by the Doctoral Education Fund of the Education Ministry of China (Grant No. 20100181110086) and the National Natural Science Foundation of China (Grant Nos. 11104190 and 10974138).

Pressure-induced structural transition and thermodynamic properties of RhN2 and effect of metallic bonding on its hardness

Liu Jun (刘俊)a, Kuang Xiao-Yu (邝小渝)a, Wang Zhen-Hua (王振华)a, Huang Xiao-Fen (黄肖芬 )b   

  1. a Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;
    b College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, China
  • Received:2011-10-14 Revised:2011-12-26 Online:2012-07-01 Published:2012-07-01
  • Contact: Kuang Xiao-Yu E-mail:scu_kuang@163.com
  • Supported by:
    Project supported by the Doctoral Education Fund of the Education Ministry of China (Grant No. 20100181110086) and the National Natural Science Foundation of China (Grant Nos. 11104190 and 10974138).

摘要: The elastic constant, structural phase transition, and effect of metallic bonding on the hardness of RhN2 under high pressure are investigated through the first principles calculation by means of the pseudopotential plane-waves method. Three structures are chosen to investigate for RhN2, namely, simple hexagonal P6/mmm (denoted as SH), orthorhombic Pnnm (marcasite), and simple tetragonal P4/mbm (denoted as ST). Our calculations show that the SH phase is energetically more stable than the other two phases at zero pressure. On the basis of the third-order Birch-Murnaghan equation of states, we find that phase transition pressures from SH to marcasite structure and from marcasite to ST structure are 1.09 GPa and 354.57 GPa, respectively. Elastic constants, formation enthalpies, shear modulus, Young's modulus, and Debye temperature of RhN2 are derived. The calculated values are, generally speaking, in good agreement with the previous theoretical results. Meanwhile, it is found that the pressure has an important influence on physical properties. Moreover, the effect of metallic bonding on the hardness of RhN2 is investigated. This is a quantitative investigation on the structural properties of RhN2, and it still awaits experimental confirmation.

关键词: phase transition, elasticity, hardness

Abstract: The elastic constant, structural phase transition, and effect of metallic bonding on the hardness of RhN2 under high pressure are investigated through the first principles calculation by means of the pseudopotential plane-waves method. Three structures are chosen to investigate for RhN2, namely, simple hexagonal P6/mmm (denoted as SH), orthorhombic Pnnm (marcasite), and simple tetragonal P4/mbm (denoted as ST). Our calculations show that the SH phase is energetically more stable than the other two phases at zero pressure. On the basis of the third-order Birch-Murnaghan equation of states, we find that phase transition pressures from SH to marcasite structure and from marcasite to ST structure are 1.09 GPa and 354.57 GPa, respectively. Elastic constants, formation enthalpies, shear modulus, Young's modulus, and Debye temperature of RhN2 are derived. The calculated values are, generally speaking, in good agreement with the previous theoretical results. Meanwhile, it is found that the pressure has an important influence on physical properties. Moreover, the effect of metallic bonding on the hardness of RhN2 is investigated. This is a quantitative investigation on the structural properties of RhN2, and it still awaits experimental confirmation.

Key words: phase transition, elasticity, hardness

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

  • 61.50.Ks
62.20.D- (Elasticity) 46.55.+d (Tribology and mechanical contacts)