Pulsed-laser-induced transformation path of graphite to diamond via an intermediate rhombohedral graphite

The new phase transformation of hexagonal graphite to cubic diamond was exp erimentally produced without catalyst, using a high-power pulsed laser. Int erestingly, by the X-ray diffraction spectra, it was proved that this trans ition was not direct, but through an intermediate rhombohedral phase. Furth ermore, it is important that the rhombohedral phase, as the theoretical tra nsformation path of hexagonal graphite to cubic diamond, was first truly su bstantiated by our experimental results. The transformation mechanism was s uggested that diamond with hexagonal structure was obtained by the direct t ransforming of hexagonal graphite to hexagonal diamond, and diamond with cu bic structure was formed by the indirect transforming, i.e., hexagonal grap hite to rhombohedral graphite to cubic diamond.