Study on synthesis of diamond by adding magnesium silicate pentahydrate in Fe–Ni–C system

Abstract

Abstract In this paper, diamond crystals are successfully synthesized by adding magnesium silicate pentahydrate (Mg2Si3O8·5H2O) into the Fe–Ni–C system at 5.8–6.3 GPa pressure and 1300–1420 °C temperature. Our results show that the decomposition products of Mg2Si3O8·5H2O under high temperature and high pressure have significant inhibitory effects on the nucleation and growth of diamond. Moreover, with add the amount, the temperature and pressure of synthetic diamond also gradually increased. The SEM shows that the surface defects of the crystal also increase with the increase of the add amount. The IR spectroscopy results show that the content of nitrogen decreases with the increase of the add amount of Mg2Si3O8·5H2O in the crystals. The Raman spectrum shows that the Raman peak of the crystal shifts to the right as the added amount of Mg2Si3O8·5H2O increases. The PL spectrum results show that the increase in magnesium silicate pentahydrate reduces the intensity of NV− and NV0 centers in the crystal. Therefore, our research results provide important ways for understanding the formation mechanism of natural diamond.