Synthesis and nitrogen content regulation of diamond in a high-pressure hydrogen-rich environment

Abstract

The regulating nitrogen content of diamond in a hydrogen rich high-temperature and high-pressure (HPHT) growth environment was systematically investigated in this work by developing three growth systems, namely, "FeNi+Ti", "FeNi+C3N6H6", and "FeNi+Ti+C3N6H6". Optical microscopy, infrared spectroscopy, and photoluminescence (PL) spectroscopy measurements were conducted to analyse the spectroscopic characteristics of diamonds grown in these three systems. From our analysis, it was demonstrated that the presence of hydrogen in the sp3 hybrid C-H does not directly affect the colour of the diamond and facilitates the increase of Nitrogen-Vacancy (NV) center concentration in a high nitrogen content diamond. In addition, titanium plays an important role in nitrogen removal, while its impact on hydrogen doping within the diamond lattice is insignificant. Most importantly, by regulating the ratio of nitrogen impurities that coexist in the nitrogen and hydrogen HPHT environment, the production of hydrogenous IIa type diamond, hydrogenous Ib type diamond, and hydrogenous high nitrogen type diamonds was achieved with a nitrogen content of less than 1 ppm to 1600 ppm.