Tuning the Poisson's Ratio of Porous Graphene with Defects

Undergraduate #85
Discipline: Physics
Subcategory: Physics (not Nanoscience)

Greg Stewart - Rensselaer Polytechnic Institute

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In order to simulate the mechanical properties of porous graphene,
Schwarzites have been used as a model. Schwarzites are hypothetical
carbon crystals which possess negative Gaussian curvature from the introduction of
heptagonal or octagonal rings of carbon, in addition to having hexagonal rings
as in graphene. Some Schwarzites may possess Poisson’s ratios which make them ideal candidates for specialized applications.
In particular, we have analyzed three cubic families of Schwarzites
named the P, D, and G type Schwarzites. The calculations of the mechanical properties of these schwarzites were performed using the free LAMMPS source code along with the REBO empirical potential. The cell sizes range from hundreds to thousands of atoms per cubic cell. Our results show that the Poisson’s ratios can be tuned by the introduction of Stone-Wales type defects (rotation of bonds) to the schwarzites. At a critical number of defects, the Schwarzites exhibit negative Poisson’s ratios, and are stable according to the Max Born criteria. In this talk, I will show the details of our calculations and discuss possible applications of ordered porous graphene, such as auxetics.

Funder Acknowledgement(s): NSF

Faculty Advisor: Humberto Terrones, terroh@rpi.edu

Role: I performed calculations and analysis on the very large P family schwarzite, P8-31, along with all of the D and G family schwarzites.