Nanocarbon Phase Diagram and Conditions for Detonation Nanodiamond Formation

Shock-induced melting of diamond powders

“…For example, according to (9), for a typical size of 4 nm, it is only 7% lower than that for a single crystal. In the diamond stability region in the phase diagram of carbon, there is a region of liquid nanocarbon sp 3 (or liquid nanodiamond) whose lower pressure boundary is the line of the family of triple points located in the interval of 13.5-16.5 GPa [8,9]. In the same region there are the detonation pressures and temperatures of powerful explosive compositions used for the synthesis of detonation nanodiamonds.…”

“…For detonation nanodiamonds, we obtained the following simple dependence of the melting point of nanodiamonds T d on the particle size d [8,9]:…”

“…4. Position of the family of triple points and melting curves of nanodiamonds [8,9]: open points show the position of triple points according to [24,25], dashed curves are curves of the phase diagram of carbon; the numbers at the curves denote the particle size, nm. nanodiamonds are formed by crystallization of nanosized droplets behind the detonation-wave front [9,22,23].…”

“…Due to the effect of surface energy, the calculated temperature of their melting decreases considerably [8,9], which increases the chances to melt nanodiamonds in experiments.…”

Diamond-like-carbon nanoparticle production and agglomeration following UV multi-photon excitation of static naphthalene/helium gas mixtures

“…Both models of phase transition, where the diamond is formed during the detonation wave, 56 and chemical pathway, where the detonation wave forms the chemical precursors necessary for diamond growth, 18 have been suggested. For chemical growth mechanisms, temperatures of less than 1000 K and pressures between 1 kPa and 100 kPa are required.…”