Effects of B-NiS co-doping on diamonds growing along {1 1 1}-orientation under high pressure and high temperature

Abstract

Large single diamonds were successfully synthesized from NiS or B-NiS co-doping FeNi-C system under high pressure and high temperature (HPHT) in this paper. In this study, the effects of different additive amounts of NiS doping alone or B-NiS co-doping on the crystal shape, color and quality of diamond were investigated. The color of NiS doped diamonds change from bright yellow to bright green and then to grayish yellow. The color of B-NiS co-doped diamonds change from yellowish green to grayish green and black. Besides, the shape of doped crystals gradually changes from plate to tower. Fourier transform infrared (FTIR) spectra shows that with the increase of additive NiS content, the entry of nitrogen is suppressed to some extent by the entry of S into the diamond lattice, while with B-NiS co-doping, the content of nitrogen impurities increase with the increase of B content. It can be found from the x-ray photoelectron spectroscopy (XPS) results that the obtained diamonds contain B/S/N elements, with S present in the diamond lattice in the form of C–S–O. Raman measurements show that with increasing B content, the peak positions of co-doped diamonds are shifted and the full width at half maximum (FWHM) become slightly larger, but still have a high quality sp3 structure. This study not only contributes to the investigation of the formation mechanism of natural diamond, but also has important implications for the enrichment of diamond species and the expansion of synthetic diamond applications.