Synthesis and characterization of IIa-type S-doped diamond in FeNi catalyst under high pressure and high temperature conditions

In this work, service through nitrogen getter we have successfully synthesized sulfur(S) doped IIa-type diamond single crystals at 1400 °C and 5.5 GPa in FeNi-C system. We found that the synthetic diamond are mainly composited of the {111} faces because of the addition of S in the synthesis system. In addition, the color of our produced diamond changed from white to light brown and the shape of diamond changed from Cub-Octahedron to Octahedron with increase of S addition in the FeNi-C system. Furthermore, we notice that many kinds of defects, such as stratiform defects, craters and inverted pyramid defects appeared on the surfaces of diamonds induced by the additive of S. The FTIR results show that the obtained diamond crystals are IIa-type diamonds, containing less than 1 ppm nitrogen. XPS measurement indicates that S was successfully incorporated into our produced diamond lattice in the SC and CSO forms. Raman spectra reveal that the as-growth S-doped IIa-type diamond single crystals possess a high-quality sp3 structure. Photoluminescence (PL) spectra demonstrate that nitrogen-vacancy is formed during diamond growth. Our work also helpful for understanding the formation of nature diamond.