Researchers from CEA DAM Ile-de-France developed a procedure and a computer model capable of simulating variable conditions of explosions
Nanodiamonds are pieces of crystalline carbon, which are hundreds of thousands of times smaller than a grain of sand. These nanodiamonds have intriguing surface and chemical properties that find application in medicine, optoelectronics, and quantum computing. Researchers expose organic explosive molecules to powerful detonations in a controlled environment to forge these nanodiamonds. However, these explosive forces pose challenge to study the nanodiamond formation process.
Now a team of researchers from CEA DAM Ile-de-France developed a procedure and a computer model that helps to simulate highly variable conditions of explosions in short time scales. The team used a type of simulation known as Reactive Molecular Dynamics. The approach simulates the time evolution of complex and chemically reactive systems down to the atomic level. Actual experimental investigation is impractical, owing to the extreme and fleetingly brief conditions of a detonation. This caused the team to depend on atomic-level simulations and the results demonstrate that a precise balance of temperature and pressure evolution is required for formation of nanodiamonds. The low initial detonation pressure leads to the formation of carbon solids instead of diamonds. In instances of more than required or high pressure, the carbon ‘seeds’ of nanodiamonds become polluted with other elements including oxygen or nitrogen. This inhibits the transition to diamond.
Although the formation of nanodiamonds from detonations is described in previous studies, the atomic-level details of their formation were not analyzed in the recent past. In industrial methods, nanodiamonds are synthesized by detonation of carbon-rich organic high explosives. Moreover, nanodiamonds are produced naturally from explosive volcanic eruptions or asteroid impacts on Earth. “Our work shows that the right path seems to be a high initial pressure followed by a sharp pressure decrease,” said Xavier Bidault, a researcher at CEA DAM Ile-de-France, and a co-author on the paper. “If the precise conditions are met, nanodiamonds form. These complex pressure paths are typical of detonation processes.” The research was published in AIP Journal of Chemical Physics on September 18, 2018.