CHINESE JOURNAL OF COMPUTATIONAL PHYSICS ›› 2017, Vol. 34 ›› Issue (1): 89-98.

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Structural,Electronic and Thermodynamic Properties of Tetragonal,Monoclinic and Orthorhombic Ge3N4

YAO Xiaoling1, CHEN Dong2   

  1. 1. Institute of Architectural Engineering, Xinyang Vocational and Technical College, Xinyang 464000, China;
    2. College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China
  • Received:2015-12-14 Revised:2016-05-16 Online:2017-01-25 Published:2017-01-25
  • Supported by:
    Supported by National Natural Science Foundation of China (61501392,11304141)

Abstract: We calcuate lattice constants, volumes, elastic moduli, Vickers hardnesses and density of states of the tetragonal, monoclinic and orthorhombic Ge3N4.Fundamental properties obtained are compared with experimental data and other theoretical results, which shows good agreement.Negative formation enthalpy, linear relation between lattice deformation and pressure, and volume show that three phases retain stabilities in a pressure range of 0~20 GPa.Density of states show that Ge3N4 are semiconductors with strong s-p hybridizations.All polymorphs are brittle materials but anisotropic.Several thermodynamic properties are investigated with quasi-harmonic approach considering lattice vibrations and anharmonic effects.Helmholz free energy and internal energy show strong dependences on pressure.Interesting features are seen in heat capacity of the novel Ge3N4 nitrides, especially at high temperatures.

Key words: numerical simulation, density of states, heat capacity, free energy

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