Mechanical Properties of Phagraphene Membranes: A Fully Atomistic Molecular Dynamics Investigation
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Mechanical Properties of Phagraphene Membranes: A Fully Atomistic Molecular Dynamics Investigation J. M. de Sousa1,2, A. L. Aguiar2, E. C. Girão2, Alexandre F. Fonseca1, A. G. Sousa Filho3, and Douglas S. Galvao1,4 1 Applied Physics Department, Institute of Physics “Gleb Wataghin”, University of Campinas – UNICAMP, Campinas, São Paulo, CEP 13083-859, Brazil.
2
Departamento de Física, Universidade Federal do Piauí, Teresina-PI, 64049-550, Brazil.
3
Departamento de Física, Universidade Federal do Ceará, Fortaleza-CE, 60445-900, Brazil.
4
Center for Computational Engineering and Sciences, UNICAMP, Campinas, São Paulo, Brazil.
ABSTRACT
Recently, a new 2D carbon allotrope structure, named phagraphene (PG), was proposed. PG has a densely array of penta-hexa-hepta-graphene carbon rings. PG was shown to present low and anisotropic thermal conductivity and it is believed that this anisotropy should be also reflected in its mechanical properties. Although PG mechanical properties have been investigated, a detailed and comprehensive study is still lacking. In the present work we have carried out fully atomistic reactive molecular dynamics simulations using the ReaxFF force field, to investigate the mechanical properties and fracture patterns of PG membranes. The Young's modulus values of the PG membranes were estimated from the stress-strain curves. Our results show that these curves present three distinct regimes: one regime where ripples dominate the structure and mechanical properties of the PG membranes; an elastic regime where the membranes exhibit fully planar configurations; and finally am inelastic regime where permanent deformations happened to the PG membrane up to the mechanical failure or fracture.
INTRODUCTION Recently, a new two-dimensional nanostructure composed of 5-6-7 rings of carbon atoms, named phagraphene (PG) [1], was proposed. This new form of carbon allotrope is predicted to have very interesting electromechanical properties, as compared to graphene [1]. PG presents anisotropic and relatively low thermal conductivity: in average of 218 ± 20 Wm-1K-1 along the armchair direction and 285 ± 29 Wm-1K-1 along the zigzag direction at room temperature [2]. Because of its distinct geometric
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arrangement of carbon atoms, PG exhibits interesting mechanical properties. A recently theoretical study performed using molecular dynamics (MD) methods with Tersoff empirical potential, showed that PG membranes have an elastic modulus of approximately 800 ± 14 GPa [2]. Another theoretical work showed that PG membranes might present other non-planar configurations [3], which can significantly influence PG mechanical properties. In spite of these studies a detailed and comprehensive study of PG mechanical properties is still missing and it is one of the objectives of the present work.
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