On phase changes of carbon under dynamic conditions as observed by STEM

A mechanism of diamond formation under dynamic conditions was proposed recently. In its essence, four stages were discussed of nucleation, growth and survival of diamond articles formed by application of ultrashort pressure pulses at very high temperatures to mixtures of graphite and copper or iron. Formation of diamond nuclei via a solid-gas-liquid-solid sequence of phase transitions was suggested. The results of numerous experiments were found to be in satisfactory agreement with the proposed model and are described elsewhere. Many analyses of the recovered samples were carried out with a Philips 300 transmission electron microscope. The resolution, however, of a conventional TEM is not always sufficient to detect very small particles. Therefore, additional work was carried out using a STEM (VG Microscopes Ltd, HB5). The very unique structures observed will be briefly described in this note.