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This paper reprots that with Ni-based catalyst/solvent and with a dopant of NaN 3,large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus (SPD-6×1200),and the highest nitrogen concentration reaches approximately 1214-1257 ppm calculated by infrared absorption spectra.The synthesis conditions are about 5.5 GPa and 1240-1300 C.The growth behaviour of diamond with high-nitrogen concentration is investigated in detail.The results show that,with increasing the content of NaN 3 added in synthesis system,the width of synthesis temperature region for growth high-quality diamonds becomes narrower,and the morphology of diamond crystal is changed from cube-octahedral to octahedral at same temperature and pressure,the crystal growth rate is slowed down,nevertheless,the nitrogen concentration doped in synthetic diamond increases.
This paper reprots that with Ni-based catalyst / solvent and with a dopant of NaN 3, large green single crystal diamonds with perfect shape are are synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus (SPD-6 × 1200), and the highest nitrogen concentration reaches approximately 1214-1257 ppm calculated by infrared absorption spectra. The synthesis conditions are about 5.5 GPa and 1240-1300 C. The growth behavior of diamond with high-nitrogen concentration is investigated in detail. These results show that, with increasing the content of NaN 3 added in synthesis system, the width of synthesis temperature region for growth high-quality diamonds becomes narrower, and the morphology of diamond crystal is changed from cube-octahedral to octahedral at the same temperature and pressure, the crystal growth rate is slowed down, nevertheless, the nitrogen concentration doped in synthetic diamond increases.