Effect of Cooling and Depressurizing on the Efficiency of Shock-induced Nanodiamond Synthesis: A Molecular Dynamics Study
Paper ID : 1357-ICNS
Authors:
Maryam Mahnama *1, Ali Shomali2
1School of Mechanical Engineering, College of Engineering, University of Tehran, 11155-4563, Tehran, Iran
2Department of Mechanical and Process Engineering, ETH Zurich, Zurich,Switzerland
Abstract:
Shock-induced phase transitions of C60 fullerene crystal structure into amorphous nano-diamond is investigated through molecular dynamics simulations. For this purpose, the Hugoniostat scheme is employed to provide the material behavior in a wide range of shock strength. The shock pressure corresponding to the Hugoniot elastic limit and phase transition (PT) are extracted from the Hugoniot curves at 27 and 63 GPa, respectively, which are in close correlations with former experimental results. A quenching process is also imposed on the post-shock material to bring it into the ambient conditions. The quenching results revealed that the slower cooling rates show a slightly higher sp3 fraction and bring the material into a lower energy level. Depressurization results, highlight the fact that the cooling rate should be high enough to prevent the material from liquefying. Moreover, the simulation results emphasize on the importance of a quenching process within the shock compression. The simulation results are in agreement with some evidences in former experiments. These results, point out the substantial importance of higher rapid quenching rates for nano-diamond synthesis
Keywords:
Amorphous Nano-Diamond; Fullerene C60; Shock Compression and Rapid Quenching; Regraphitization; Molecular Dynamics Simulation
Status : Abstract Accepted (Poster Presentation)