A systematic study of the diamond-graphite structural phase transition in ultradisperse-diamond clusters obtained by the detonation technique is reported. Samples of two types, differing in the kinetics of detonation-product cooling, were investigated. The phase transition was achieved under heating in an inert atmosphere in the temperature range 720–1400 K. The transition was identified by Raman scattering and x-ray diffraction data. Raman and x-ray characterization showed the ultradisperse diamond, irrespective of the cooling rate used, to be cluster material possessing diamond structure with a characteristic nanocrystal size of 43 Å. The diamond-graphite phase transition in ultradisperse diamond is shown to start from the cluster surface inwards at T pt ≈1200 K, i.e. at substantially lower temperatures than is the case with bulk diamond single crystals.
No takes yet. Share an insight, caveat, or question.
Aleksenskii et al. (1997) studied this question.