再结晶石墨对宝石级金刚石单晶生长的影响

Influence of recrystalized graphite on gemological class diamond monocrystal growth

高温高压温度梯度法生长宝石级金刚石单晶的过程中,尽管处在金刚石稳定区内,却经常发现,有亚稳态的再结晶石墨存在。本研究发现,作为一种晶体,大量再结晶石墨的析出和生长对宝石级金刚石单晶的生长速度有较为明显的抑制作用,并且再结晶石墨更容易在较高温度合成区内出现。例如,使用N iM nCo触媒进行宝石级金刚石单晶合成过程中,随着合成温度的提高,当大量多余碳源不再以金刚石自发核形式析出,而是以大量片状再结晶石墨形式围绕在晶体周围时,晶体的生长速度有了大幅度的降低,从相对低温时的约3.0m g/h降到较高温度时的1.0m g/h。

During the process of gemological class diamond growing by temperature grads method at high temperature and high pressure,metastable re-crystallized graphite often has been found in the area though it is in a diamond stable area.The research has found that as a crystal,the separation and growth of large amount of re-crystallized graphite would have obviously restrained the growing speed of the gemological class single diamond crystal and the re-crystallized graphite tends to occur in a relatively high temperature synthetic area.For example,during gemological class diamond monocrystal synthesizing process with NiMnCo catalyst,with increasing the synthesis temperature,when the excess carbon source no longer separate out in a form of diamond spontaneous nucleus and surround the crystal in form of slice recrystallized graphite,growing speed of the crystal reduces considerably from about 3.0 mg/h at relatively lower temperature to 1.0mg/h at higher temperature.