Study On The HPHT Synthesis Of Diamond Single Crystals With Mg₂Si₃O₈·5H₂O Additive

Diamond is common in our daily life,industrial production and engineering construction.It has excellent insulation,thermal conductivity and high hardness.It can also be used as a kind of gem and is widely used in many scientific research fields.At present,most of the diamonds we use are artificial diamonds.Due to the progress of various technologies,the properties of artificial diamonds have been optimized,and many properties are even better than natural diamonds,which have been applied in many fields.However,the origin of natural diamond remains a mystery,and little is known about it.Therefore,the research on the formation of natural diamond and the understanding of its growth environment has been a hot topic in the field of diamond research.Since 1954,the first high temperature and high pressure test technique was used to synthesize synthetic diamond by solvent and graphite,some metals?such as Fe,Co,Ni,etc.?and their alloys have been used as catalysts to successfully synthesize diamond crystals.In addition,the researchers also grew diamond crystals in the nonmetallic system?Na₂CO₃,Na₂SO₄?.It is well known that diamonds are one of the major concentrators of carbon in the earth's crust and the most critical link in the deep carbon cycle.Magnesium and silicon are the most abundant elements on earth,and are also abundant in the earth's mantle.The underlying structure of the mantle consists of refractory peridotite rocks of different thickness,and peridotite is a magnesium-rich silicate rock.However,there are few studies on the addition of silicate to metal solvent for the growth of diamond.In this paper,some properties of Mg₂Si₃O₈·5H₂O under high temperature and high pressure were firstly studied.The results showed that Mg₂Si₃O₈·5H₂O was generated by other substances under high temperature and high pressure.On this basis,Mg₂Si₃O₈·5H₂O was added to the Fe-Ni-C system,and diamond crystals were successfully synthesized by the film growth method under 5.8-6.3GPa pressure and temperature of 1250-1420?.Diamond crystals were characterized by scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FTIR?,Raman spectroscopy and photoluminescence spectroscopy?PL?.The results showed that Mg₂Si₃O₈·5H₂O had a significant inhibitory effect on the nucleation and growth of diamond.With the increase of doping amount,the temperature and pressure conditions of synthetic diamond also increased gradually,and the crystal surface defects increased.The nitrogen content in the crystal decreases gradually.The crystal's Raman peak will also shift to higher frequencies.The core strength of NV^-and NV⁰decreases in the crystal.It is believed that our research results will provide reference value for understanding the formation mechanism of natural diamond.