碳源扩散不均一性对宝石级金刚石单晶生长的影响

Influence of inhomogeneous diffusion of carbon source on growth of gem-grade synthetic diamonds

高温高压温度梯度法生长优质宝石级金刚石单晶过程中,晶体生长主要由碳源在触媒中的扩散过程决定。本研究通过有限元对碳源对触媒的扩散过程进行了简单模拟,结果发现,受温度梯度法特定组装结构影响,实际晶体在生长过程中,由高温端扩散下来的碳源在触媒中的分布是相当不均匀的。对晶体生长来说,这种碳源扩散不均一性会直接影响晶体的生长过程。在籽晶粒度超过2mm时,晶体中心部位出现较多包裹体,或者生长表面无法生长愈合。

For the growth of superior gem-grade large synthetic diamond crystals by temperature gradient method （TGM）, the crystal growth was mainly determined by the diffusion process of carbon source in the metal/solvent. In this paper, the diffusion process of carbon source is simulated by the Finite Element Analysis （FEA）, and it is found that the diffusion of carbon source in metal/solvent from higher temperature position is very inhomogeneous in the growth process, which is resulted from the special assembly structure, and this inhomogeneous diffusion is also observed directly by the shapes of remnant carbon source. It can influence markedly the gem-grade diamond growth process, especially for growing crystals with seed crystals more than 2.0mm grit sizes . More inclusions will occur at the center part of the crystal or the growing surface can not he healed up in that case.