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Effects of Hydrostatic Pressure and Biaxial Strains on the Elastic and Electronic Properties of β ‐Si 3 N 4
Author(s) -
Zhu Haiyan,
Shi Liwei,
Li Shuaiqi,
Zhang Shaobo,
Tang Tianliang,
Xia Wangsuo
Publication year - 2018
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201700676
Subject(s) - hydrostatic pressure , materials science , debye model , band gap , vickers hardness test , condensed matter physics , anisotropy , strain (injury) , ultimate tensile strength , elastic modulus , bulk modulus , composite material , thermodynamics , optics , physics , optoelectronics , medicine , microstructure
First principles calculations have been performed to investigate the effects of hydrostatic pressure and biaxial strains ( ϵ xx ) on the electronic and elastic properties of β ‐Si 3 N 4 . Both bulk modulus and Vickers hardness enhance (decrease) with pressure and compressive (tensile) ϵ xx . The evolution of B H / G H ratio indicates that β ‐Si 3 N 4 has a better (worse) ductile behavior under pressure and compressive (tensile) ϵ xx . The 3D plots of Young's modulus show huge difference in mechanical properties between [0001] direction and a‐b plane and the anisotropy becomes larger by using strain engineering. The sound velocities and Debye temperature are also discussed. The energy gap increases monotonically with pressure, however, strain‐induced changes in band gap are asymmetric and nonlinear. β ‐Si 3 N 4 undergoes an indirect to direct band gap transition at biaxial strain of 5%, while β ‐Si 3 N 4 is always an indirect band gap semiconductor under pressure and compressive strains.