SHOCK-WAVE-INDUCED PHASE-TRANSITION IN C-N FILMS

New data on the phase transition in C:N films during shock wave compre ssion are discussed. The initial films were obtained by ion-assisted c arbon condensation method under the conditions of nitrogen-carbon glow discharge. Electron diffraction patterns of these films are character ized by a broad diffraction maximum d=3.79 Angstrom. The structure of the films can be interpreted in terms of densely packed carbon chain c lusters (a=4.38 Angstrom). These films were subjected to impulse compr ession at 14 GPa in recovery experiments (duration of compression impu lse is 2 mu s). The electron diffraction investigation shows that unde r these conditions partial crystallization of the specimen takes place . The mean size of crystallites is about 1 mu k. The crystal lattice i s of hexagonal type with a=4.38 Angstrom, which coincides with diffrac tion maximum of the initial film and demonstrates the crystallization of an amorphous phase. Electron diffraction pattern treatment by the P atterson function method have yielded the (001) projection of charge d ensity distribution. This C:N phase significantly differs from that pr edicted theoretically. By Auger Electron spectroscopy and carbon KVV A uger lineshape deconvolution treatment the distribution of electron de nsity in the valence band of C:N films was performed. (C) 1997 Elsevie r Science S.A.