HPHT synthesis of diamond with high concentration nitrogen using powder catalyst with additive Ba(N 3) 2

In this paper, high quality green industrial diamond crystals were synthesized from the system of Fe 70Ni 30–graphite with additive Ba(N 3) 2 in a china-type large volume cubic high-pressure apparatus (CHPA). FTIR spectra show that the highest nitrogen concentration in the synthesized diamond crystals is up to approximately 2400 ppm. The synthetic diamond crystals exhibit green or deep green color. The shape of synthetic crystals is mainly cub-octahedron. Partial strip crystals are also observed, which may be formed from the stretched cub-octahedron having elongated (100) and (111) crystal faces. It is also found that the synthesis conditions (temperature and pressure) increase with the increasing quantity of Ba(N 3) 2 additive.