Journal
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
Volume 113, Issue 2, Pages 483-490Publisher
SPRINGER HEIDELBERG
DOI: 10.1007/s00339-013-7551-4
Keywords
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Funding
- Defense Threat Reduction Agency (DTRA) [BRBAA08-C-2-0130, HDTRA1-13-1-0025]
- US Nuclear Regulatory Commission Faculty Development Program [NRC-38-08-950]
- US Department of Energy (DOE) Nuclear Energy University Program (NEUP) [DE-NE0000325]
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We investigate the mechanical properties of proposed graphene-like hexagonal gallium nitride monolayer (g-GaN) using first-principles calculations based on density-functional theory. Compared to the graphene-like hexagonal boron nitride monolayer (g-BN), g-GaN is softer, with 40 % in-plane stiffness, 50 %, 46 %, and 42 % ultimate strengths in armchair, zigzag, and biaxial strains, respectively. However, g-GaN has a larger Poisson's ratio, 0.43, about 1.9 times that of g-BN. It was found that the g-GaN also sustains much smaller strains before rupture. We obtained the second-, third-, fourth-, and fifth-order elastic constants for a rigorous continuum description of the elastic response of g-GaN. The second-order elastic constants, including in-plane stiffness, are predicted to monotonically increase with pressure while the Poisson's ratio monotonically decreases with increasing pressure. The sound velocity of a compressional wave has a minima of 10 km/s at an in-plane pressure of 1 N/m, while as a shear wave's velocity monotonically increases with pressure. The tunable sound velocities have promising applications in nano waveguides and surface acoustic wave sensors.
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