Diamond growth in a high temperature and high pressure Fe–Ni–C–Si system: Effect of synthesis pressure

Pressure is one of the necessary conditions for diamond growth. Exploring the influence of pressure on growth changes in silicon-doped diamonds is of great value for the production of high-quality diamonds. This work reports the morphology, impurity content and crystal quality characteristics of silicon-doped diamond crystals synthesized under different pressures. Fourier transform infrared spectroscopy shows that with the increase of pressure, the nitrogen content in the C- center inside the diamond crystal decreases. X-ray photoelectron spectroscopy test results show the presence of silicon in the diamond crystals synthesized by adding silicon powder. Raman spectroscopy data shows that the increase in pressure in the Fe–Ni–C–Si system shifts the Raman peak of diamonds from 1331.18 cm⁻¹ to 1331.25 cm⁻¹, resulting in a decrease in internal stress in the crystal. The half-peak width decreased from 5.41 cm⁻¹ to 5.26 cm⁻¹, and the crystallinity of the silicon-doped diamond crystals improved, resulting in improved quality. This work provides valuable data that can provide a reference for the synthesis of high-quality silicon-doped diamonds.