Formation of 250-μm-diameter diamond crystals by combustion flame method: Effects of preformation of molybdenum oxide on the substrate

Abstract

Combustion flame method using acetylene and oxygen has recently proved itself to be a powerful tool to obtain qualified diamond microcrystals with excellent easiness of the performance. Analysis on the spatial variation of the morphology of the deposited film by this method indicates that both the carbon-bearing radicals from the inner flame and the molybdenum oxide formed by the outer flame are the essence of the growth. The latter aspect has therefore been more definitely incorporated into the process by forming an oxide film prior to the deposition. This preoxidation, together with the simultaneous application of a magnetic field proposed recently by the authors, has led to a drastic suppression of the graphite formation and an excellent increase of the deposited area and of the microcrystal diameter of the diamond. Especially, crystals as large as 250 μm have been successfully grown.