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 o xyacetylene flame on the molybdenum substrates under atmospheric condi tions. The study deals with morphological evolution of diamond films i n combustion synthesis at different temperatures of the substrate as a basis for understanding the nucleation and growth mechanisms of the d iamond phase. The films and particles were studied by scanning and tra nsmission electron microscopes and were characterized by Raman spectro scopy. The best results, namely, a polycrystalline diamond film and pe rfect octahedral crystals, were obtained at R (O-2/C2H2) = 1.0, gas fl ow rate F= 2.21 min(-1), distance between flame-corn and the surface o f the substrate d=2 mm. Raman shift: 1332 cm(-1), the crystal growth r ate: 50 Angstrom s(-1). It has been stated that diamond particles on m olybdenum 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.