Synthesis of diamond crystals from oxygen-acetylene flames on a metal substrate at low temperature

Diamond films and particles that were synthesized by deposition from oxyacetylene flame on the molybdenum substrates under atmospheric conditions. The study deals with morphological evolution of diamond films in combustion synthesis at different temperatures of the substrate as a basis For understanding the nucleation and growth mechanisms of the diamond phase. The films and particles were studied by scanning and transmission electron microscopes and were characterized by Raman spectroscopy. The best results, namely, a polycrystalline diamond film and perfect octahedral crystals, were obtained at R (O-2/C2H2) = 1.0, gas how rate F = 2.2 l min(-1), distance between flame-corn and the surface of the substrate d = 2 mm. Raman shift: 1332 cm(-1), the crystal growth rate: 50 Angstrom s(-1). It has been stated that diamond particles on molybdenum surface can be grown at the surface temperature T = 873-1123 K which is lower by ca 100-150 K than the temperature reported in the known studies of the flame method. (C) 1998 Elsevier Science Ltd. All rights reserved.