DETONATION AND SHOCK SYNTHESIS OF NANODIA MONDS

A comprehensive bibliography describes the current knowledge about the synthesis of diamond. The synthesis by explosives has been realized b y a simple device allowing us to follow the thermal and light effects. Carbon yields (detonation soot) are from 32 to 36% by using TNT and h exolite. The presence of diamond, about 60%, in the soot, has been con firmed by X-ray diffraction. The synthesis by shock compression has be en carried out by an original device. The X-ray results of the carbon products obtained from different carbon precursors (graphite, coal, ca rbon black) show the presence of nanodiamonds because of the high pres sure applied by our device. The diamond yield is influenced by the par ticle size and the dispersion of black carbon. The obtained nanodiamon ds have a structure of a diamond core with a graphitic shell. It seems that the graphitic shell observed systematically around the diamond p articles are formed during the regraphitisation of diamonds when the p ressure drops sharply and the temperature of the sample stays high. Th e copper powder, acting as a thermal buffer, makes it possible to stop the process before the total graphitisation. Finally our experience s hows that we can obtain diamond with all the carbon materials on condi tion that adequate pressures and temperatures are applied. The synthes is process of diamond by shock seems reconstructive, which could corre spond to the very first steps of the synthesis by high pressure and hi gh temperature.