Study of ultradispersed diamond powders obtained using explosion energy

The physico-chemical properties of diamon-containing blacks (A1) obtained by the dynamic method in srongly nonequilibrium conditions as well as of ultradispersed diamond (UDD) obtained by the treatment of A1 in perchloric acid (A2) and in a mixture of nitric and sulphuric acids (A3) are studied. According to electron microscopy data, the characteristic particle size in sample A1 ranges from 70–100 A. On dark-field micrographs there are reflections of graphite-like structures with the region of coherent scattering 5–10 A and reflections of diamond particles 20–50 A in size. The treatment of A1 with acids decreases the size of particles by some 10–15 A, their surfaces being modified with chlorine- (A2) and sulphur- and nitrogen-containing fragments (A3). As found by Fourier-IR spectroscopy, the UDD surface has a large amount of oxygen in the form of , and other groups. The presence of admixtures in the bulk and on the surface of diamond particles may cause the deviation of the lattice parameter a and density of the samples from the corresponding values for large diamond crystals. The presence of surface functional groups makes possible chemical modification of UDD.