宝石级金刚石的生长速度与晶体品质的关系

Relationship between gem diamond quality and growth rate

高温高压温度梯度法是一种有效的合成宝石级金刚石单晶的方法。金刚石生长速度的控制非常关键。金刚石生长速度过快,得不到优质单晶;生长速度太慢又不利于商业化生产。在本文中我们在国产六面顶液压机上合成Ib型宝石级金刚石。对短时间(3小时)合成的晶体生长速度与金刚石品质之间的关系进行了研究。对于生长时间小于3小时的金刚石:当生长速度超过2mg／h时,晶体的品质较差;当生长速度小于2mg／h时,可以获得优质晶体。我们分析了实验中包裹体、熔坑、自发核和连晶的形成原因。并认为过快的生长速度是导致这些现象出现的主要因素。所以为获得优质晶体,在金刚石生长的初期(3小时内)生长速度应控制在2mg／h以下。

HPHT gradient temperature method is an effective technique to grow gem diamonds. In this paper type Ib diamond crystals was synthesized in a China-made cubic press. The relationship between diamond quality and growth rate was researched. All the crystals were grown within 3 hours. When the growth rate was faster than 2mg/h, the quality of the diamond was poor. High quality diamonds were obtained when the growth rate is slower than 2mg/h. Inclusions, cave, spontaneous nucleation and crystal stock were studied. The fast growth rate is the main reason to cause these phenomena. So it is concluded that the growth rate should be slower than 2mg/h to get high quality diamonds when the growth time is shorter than 3 hours.