Relationship between content of carbide in catalyst and growth of diamond single crystal

Diamond single crystal was synthesized at high temperature and high pressure in a six-anvil high pressure apparatus with iron-based catalyst made by powder metallurgy.It is found that the synthesized products on different section in a same assembled bulk are markedly different even under the same synthetic technology.The phase and composition of catalyst that corresponds to different synthesizing effects were investigated by means of XRD and EPMA.The results indicate that the better quality and higher yield of diamond can be obtained for the catalyst with more carbides.However,only few diamond nucleates in the catalyst with less carbide and bulk graphite.It is suggested that in order to obtain better results of diamond growth,a large number of metal carbides is essential because it likely is the direct carbon source for diamond growth at high temperature and high pressure.