不同金属触媒对金刚石中氮含量的影响

Effect of metal solvents on nitrogen content in synthetic diamonds

利用高温高压静压触媒法合成金刚石单晶过程中,如果不采取特殊除氮措施,晶体中的氮杂质含量会因为触媒不同而不同,晶体颜色表现出深度不同的黄色。本研究就不同触媒利用温度梯度法合成的宝石级金刚石单晶中的杂质氮进行了显微红外测试,并且发现当触媒中微量与氮有关的添加剂存在时,晶体中氮含量会发生明显变化。例如,使用N i基N iMnCo触媒得到的宝石级金刚石单晶含氮量大约在400×10-6;而采用Fe基FeN iCo触媒得到的晶体含氮量约在150×10-6。然而当触媒中存在微量(1wt‰)NaN3时,无论Fe基还是N i基触媒,晶体中的含氮量均提高到700×10-6左右,这说明触媒中存在微量添加剂时可能会明显影响到触媒和晶体的性质。

When growing diamond crystals with metal solvents under HPHT,if no special means to remove nitrogen impurity in crystals,the crystal color show pale yellow to green yellow according to different metal solvents.In this paper,Micro-IR absorption spectrum measurements are used to determine the nitrogen content in large synthetic diamonds grown with different metal solvents by temperature gradient method.It is found that,when a trace of additives related to dispersed nitrogen is added into the metal solvents,the nitrogen content changes obviously.For example,with Ni-based NiMnCo alloy as metal solvent,the nitrogen content in diamond crystals is about 400×10^(-6);but with Fe-based FeNiCo alloy,the content is about 150×10^(-6).However,when NaN_3(1wt‰) is added into the metal solvents,whether Fe-based or Ni-based catclyst was used,the nitrogen content in diamonds increase to about 700×10^(-6),this means that a trace of additives in the catalyst can influence the growth characters of crystals remarkably.