About this Abstract |
| Meeting |
MS&T22: Materials Science & Technology
|
| Symposium
|
Mesoscale Phenomena in Functional Polycrystals and Their Nanostructures
|
| Presentation Title |
A New Carbon Solid: Layered Amorphous Graphene — Its Structure, Cohesion and Space-projected Conductivity |
| Author(s) |
Rajendra Thapa, Chinonso Ugwumadu, Kishor Nepal, Jason Trembly, David Drabold |
| On-Site Speaker (Planned) |
David Drabold |
| Abstract Scope |
Using first principles molecular dynamics, we have shown that carbon with densities in a window around 2.4 gm/cc undergoes a disorder-order transition when annealed near 3000K. The network self-organizes and forms planes after 10-20 ps — planes of amorphous graphene, separated by approximately the experimental inter-plane distance of .33 nm in graphite. The amorphous graphene planes are sp2, but with ring disorder (pentagons, hexagons, heptagons etc.). The galleries are filled with a fairly homogeneous electron gas arising from the pi orbitals. The cohesion is not due to van der Waals (fluctuating dipole) interactions as sometimes asserted for graphite (since these effects are not included in our Hamiltonian). We observed graphitization even for a random initial configuration, leading to more defects than for an amorphous carbon initial state. For all the models, we discuss the electronic properties and the space-projected electronic conductivity, which provides real-space information about conduction pathways in materials. |