Synthesis and characterization of boron and nitrogen co-doped diamond crystals under high pressure and high temperature conditions

Abstract

In this study, diamond crystals co-doped with boron and nitrogen were synthesized via a temperature gradient method at 5.3–5.8 GPa and 1300–1550 °C by adding B and N dopants to a system of carbon and an Fe-based solvent catalyst. The obtained co-doped diamond crystals were characterized via optical microscopy (OM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Our results indicated that the obtained B/N-co-doped diamond crystals were green in color and nearly transparent. The surface characteristics were different for the (100) and (111) crystal faces. In the B/N-co-doped diamonds, B, C, and N combined with each other and formed stable chemical bonds. The nitrogen concentration of the co-doped diamond crystals was much higher than that of the single doped crystals, and the form of nitrogen atoms was also different. The Raman characteristic peak of the co-doped diamond crystals almost did not shift as compared to that of the undoped or single doped crystals.