Synthesis and growth mechanism of diamond and cubic boron nitride

本文将对金刚石和立方氮化硼的形成和生长机理进行综述。在本研究中，我们使用Ni、Ni- ti、Ni- nb、Fe-B、Fe-Co和Fe-Co- ti等金属合金溶剂进行金刚石的合成和生长实验。采用碱土和碱土氮化硼化合物CaLiBN2作为cBN生长的溶剂。氮是金刚石中的主要杂质，通过加入Ti、Zr、Nb等吸气元素可以去除氮。然而，对氮的捕集机理的研究很少。添加较高的Ti含量或在较高的温度下生长，使金刚石晶体中氮的含量大大降低。以Fe-Co - Ti合金为溶剂，氮含量明显降低。利用金刚石在晶种上的再结晶工艺，开发了高纯金刚石的生长方法。作为cBN生长溶剂的CaLiBN_2的晶体结构分析表明，结构中存在Li和N缺陷，这些缺陷可能对降低cBN生成的阈值压力起作用。

On the formation and growth mechanism of diamond and cubic BN carried out in the present study will be summarized.In the present study, we used metal alloy solvents such as Ni, Ni-Ti, Ni-Nb, Fe-B,Fe-Co and Fe-Co-Ti used for diamond synthesis and growth experiments. Alkali and alkaline earth boron nitride compound such as CaLiBN2 was used as solvent for cBN growth.Nitrogen, which is a major impurity in diamond, can be eliminated by the addition of getter element such as Ti, Zr and Nb. However, few studies have been reported on the mechanism of the nitrogen gettering. Content of nitrogen in the diamond crystals decreased greatly by adding higher Ti content or growth at higher temperature. The content of nitrogen decreased remarkably when we use Fe-Co Ti alloy as solvent.We developed growth method of high pure diamond utilized recrystallization process of diamond on the seed crystal.Crystal structure analysis of CaLiBN_2 which used as solvent of cBN growth suggested that Li and N defect are present in the structure and these defects plays possible role of decreasing threshold pressure of the cBN formation.