Effect of Fe₆N₂ on diamond growth under high pressure and high temperature conditions

A study on the growth of high-nitrogen diamond with Fe6N2 addition in the FeNi-C system was conducted at P = 5.5-5.6 GPa and T = 1320-1350 degrees C. The experiments indicate that an increase in the addition ratio of Fe6N2 from 1 wt% to 4 wt% significantly leads to a rise in the crystal nitrogen content from 200 ppm to 2043 ppm and a decrease in the growth rate value of crystals from 1.48 mg/h to 0.11 mg/h. However, the growth of high-quality crystals becomes exceedingly challenging when the addition ratio exceeds 4 wt%. After growth regulation, the results demonstrated the successful cultivation of high-quality diamonds with a 4.5 wt% addition ratio, with a maximum nitrogen content reaching 2800 ppm. Infrared spectroscopy measurements conducted at different positions within the crystal indicate a relatively uniform distribution of nitrogen concentration within the crystals grown with a 4.5 wt% addition ratio. Furthermore, the multi-seed growth method was employed to achieve multi-particle growth of high-quality high-nitrogen diamonds within the same synthesis chamber under addition ratios of 3 wt%. and 4.5 wt% respectively.