Synthesis of high- nitrogen-content doped-g-C 3 N 4 (A new nitrogen source) diamond under high-pressure and high-temperature conditions

This study reports the successful synthesis of high -nitrogen -content diamond (2723 ppm) within the Fe -Ni -C -N system, utilizing g-C 3 N 4 as a new nitrogen source via the temperature gradient method under high -pressure and high-temperature (HTHP) conditions. The study investigated the role of nitrogen atoms in facilitating the growth of large diamonds with {111} plane orientation. Analysis of crystal morphology, nitrogen defect content, and nitrogen incorporation forms were conducted. As the amount of g-C 3 N 4 increased, the crystal size decreased, the color changed from yellow to green with increasing depth, and the growth rate notably decreased. The Fourier transform microscopy infrared spectroscopy (FT-IR) characterization revealed increased nitrogen content within the crystal due to nitrogen atom introduction. Raman characterization indicated increased residual stress with higher nitrogen content, leading to shifts in Raman peak positions and broadening of half-peak widths of the diamond. Photoluminescence (PL) characterization indicated that g-C 3 N 4 addition increased, resulting in a fading state of NV - and W8 defects. The results indicated that g-C 3 N 4 , as a new nitrogen source, exhibited superior doping efficiency within the diamond lattice compared with traditional nitrogen sources. The study offered valuable insights into the preparation and potential applications of high -nitrogen diamond single crystals.