Preparation and characterization of diamond single crystals in Fe-B-C system under high pressure and high temperature

High quality boron-doped diamond single crystal was synthesized by using low value pure iron powder as catalyst using a China-type cubic high-pressure apparatus.It is found that the synthetic conditions(temperature and pressure)of diamond increases with the increase of boron addition.The crystal color changes from light yellow to black, and the crystal is mainly in octahedral form.Scanning electron microscopy(SEM)is used to analyze the morphology of boron-doped diamond.It is found that there are round pits in micron size on the {111} crystal surface.According to Raman spectroscopy, the characteristic peak of diamond is blue shifted, and the crystal quality decreases with the increase of half peak width.The strong 2 800 cm^-1 B-C bond absorption peak of Ⅱ b-type diamond can be found by infrared spectrum.In the pure iron catalyst system, the suitable boron addition amount is 0.2%~0.8%, and the quality boron-doped diamond can be synthesized by optimizing preparation technology.