Effect of nitrogen–hydrogen co-doping on diamond growth

Abstract

Nitrogen and hydrogen impurities play a vital role in the growth of diamonds. A series of nitrogen–hydrogen co-doped diamonds was synthesized through the temperature gradient growth method using melamine (C3H6N6) and ferrocene (Fe(C5H5)2) as nitrogen and hydrogen sources at 6.0 GPa and 1368–1384 °C. NiMnCo alloy was used to catalyze the synthesis of the diamond, and Ni was used as a hydrogen storage material to facilitate the introduction of hydrogen into the diamond. The results showed that the introduction of hydrogen slightly affected the growth rate of the diamond crystal. In contrast, the introduction of nitrogen impurities decreased the growth rate of the diamond crystal. The PL spectra of the samples showed that the high‑nitrogen content in the diamond was not conducive to the formation of the NV color center, and the appropriate nitrogen content favored the formation of the NV color center. Fourier transform infrared spectra of the diamond revealed that the introduction of hydrogen promoted the aggregation of nitrogen atoms and increased the A-center nitrogen ratio in the diamond. Raman spectroscopy results showed that the introduction of hydrogen weakened the residual stress in the diamond. These findings help to understand the crystal quality of natural diamonds with hydrogen-rich and aggregated nitrogen impurities and also provide a solution for reducing the residual stress of diamonds.