计算物理 ›› 2017, Vol. 34 ›› Issue (1): 89-98.

• 研究论文 • 上一篇    下一篇

四方、单斜和正交Ge3N4的结构、电子结构和热力学性质

姚晓玲1, 陈东2   

  1. 1. 信阳职业技术学院 建筑工程学院, 信阳 464000;
    2. 信阳师范学院 物理电子工程学院, 信阳 464000
  • 收稿日期:2015-12-14 修回日期:2016-05-16 出版日期:2017-01-25 发布日期:2017-01-25
  • 通讯作者: 陈东(1982-),male,master,associate professor,major in computational physics,E-mail:chchendong2010@163.com

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)

摘要: 数值计算了四方、单斜和正交结构Ge3N4的点阵常数、晶胞体积、弹性模量、维氏硬度和态密度.计算结果与已有的实验数据和理论值符合得很好.形成焓为负、晶格形变和晶胞体积随压强呈线性变化,表明三种相在0~20 GPa压强范围内可以保持结构稳定.态密度研究表明三种氮化锗内部存在强烈的s-p杂化.三种相都属于脆性半导体材料,具备各向异性且硬度适中.采用包含原子振动和非谐效应的准谐波近似方案,研究材料的热力学性质,发现压强对赫姆霍兹自由能和内能有显著影响.结果为进一步理解氮化锗三种新结构的电子结构和热力学性质提供初步的物理图像.

关键词: 数值模拟, 态密度, 热容, 自由能

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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