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It is demonstrated that the Chapman-Jouguet parameters for high explosives used in nanodiamond synthesis are located in the region of liquid nanocarbon; therefore, the chemical reaction zone of the detonation wave involves formation of carbon nanodroplets, which are later crystallized into nanodiamonds on the segment of the isentrope of expansion of detonation products, passing through the region of stability of nanodiamonds in the pressure range of 16.5-10 GPa and the temperature range of 3400-2900 K. Soot in the resultant mixture is the product of amorphization of nanodroplets rather than graphitization of ultrafine diamonds. The influence of detonation conditions of high-explosive charges in an explosive chamber on nanodiamond synthesis is analyzed.

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In the phase diagram of carbon, the positions of the melting and thermodynamicequilibrium curves of detonation nanodiamonds or ultrafine diamonds are found as functions of diamond particle size. The position of the set of triple points located in the ranges of pressure 13.5-16.5 GPa and temperature 2210-4470 K and determining the region of the liquid state of nanocarbon is determined. In the phase diagram of nanocarbon, the diamond region is divided into three parts according to the type of nanoparticles: nanodiamond, liquid nanocarbon (nanodrops), and amorphous nanocarbon.

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