碳素扩散场对塔状晶体合成的影响

Effects of carbon diffusion field on the synthesis of tower shape diamond crystals

高温高压温度梯度法生长宝石级金刚石时,碳素的扩散场会对晶体品质产生很大影响。不同分布的扩散场适合生长不同形貌的晶体。研究发现,图1的碳素扩散场适合生长尺寸较大的板状晶体。合成高温塔状晶体时,若β>0.6,合成出的绝大多数晶体内都会出现大量的包裹体。该扩散场不适合生长β值较大的塔状晶体。通过有限元模拟,得到了该扩散场碳素浓度等值线分布图。找到了该扩散场适合板状晶体生长的原因是碳素在扩散场的分布与板状晶体的形貌要求相匹配,与塔状晶体生长的要求相违背导致的。

In the process of growing gem diamond crystals by TGM （temperature gradient method） under HPHT （high temperature and high pressure）, carbon diffusion field has important effect on crystal quality. Certain distribution carbon diffusion field fits certain shape diamond crystals growing. It was found that the carbon diffusion field of this paper adapts to grow big tabular diamond crystals. When growing high temperature tower shaped crystals, if β〉0.6, a great deal of inclusions will appear in most of synthetic diamond crystals. The diffusion field does not fit growing tower shape diamond crystals whose β （β〉0. 6） is big. Using finite element analysis software ANSYS, we got the carbon concentration isoline distribution chart of the carbon diffusion field. We found the reason that the carbon diffusion field fits to synthesizing tabular diamond crystals and does not adapt to big β tower shape diamond crystals growing. The reason is that distribution of the carbon diffusion field mismatches with tabular diamond crystals.