Crystallization and characteristics of {100}-oriented diamond with CH4N2S additive under high pressure and high temperature**Project supported by the National Natural Science Foundation of China (Grant No. 11604246), Natural Science Foundation of Guizhou Province Education Department of China (Grant Nos. KY2017053 and KY2018343), Natural Science Foundation of Guizhou Procince Science and Technology Agency of China (Grant Nos. 20181163 and LH 20177311),

Abstract

Diamond crystallization was carried out with CH4N2S additive in the FeNiCo-C system at pressure 6.0 GPa and temperature ranging from 1290 °C to 1300 °C. The crystallization qualities of the synthetic crystals were characterized by Raman spectra and the Raman peaks located at 1331 cm−1. Fourier transform infrared (FTIR) results showed that the hydrogen-related absorption peak of the as-grown diamond was at 2920 cm−1, respectively. Interestingly, A-center nitrogen was observed in the obtained diamond and the characteristic absorption peaks located at 1095 cm−1 and 1282 cm−1. Especially, the absorption peak at 1426 cm−1 attributing to the aggregation B-center nitrogen defect was distinctly found when the CH4N2S content reached 0.3 mg in the synthesis system, which was extremely rare in synthetic diamond. Furthermore, optical color centers in the synthesized crystals were investigated by photoluminescence (PL).