Researchers at Lin University found that in the process of growing gem-quality diamond single crystals by high temperature and high pressure temperature gradient method, metastable graphite is often found in the stable region of diamond.
The study found that as a crystal, the precipitation and growth of a large amount of recrystallized graphite have a significant inhibitory effect on the growth rate of gem-quality diamond single crystal, and recrystallized graphite is more likely to appear in the higher temperature synthesis region. For example, in the synthesis of gem-quality diamond single crystals using NiMnCo catalyst, as the synthesis temperature increases, when a large amount of excess carbon source is no longer precipitated in the form of diamond spontaneous nuclei, it is surrounded by a large amount of sheet-like recrystallized graphite. At the time, the growth rate of the crystal has been greatly reduced, from about 3.0 mg/h at a relatively low temperature to 1.0 mg at a higher temperature.
The current boron-doped diamond is a research hotspot, but there are not many articles on the synthesis of diamond doped with boron oxide using Fe70Ni30 catalyst. In the experiment, a certain proportion of boron oxide was added to the graphite-Fe70Ni30 powder system and mixed uniformly, and the boron oxide-doped diamond was synthesized by high temperature and high pressure on a six-face press. The experimental results show that the addition of a certain amount of boron oxide has little effect on the synthesis pressure and temperature of diamond, but the diamond synthesized by boron oxide is different from the undoped synthetic diamond in color and surface morphology.
Diamond crystals have many remarkable features, but they are not suitable for conducting current: a pyramid-shaped lattice known to be composed of carbon atoms is an insulator. But in recent years, diamonds have been made conductive by introducing foreign atoms through a step called doping. However, this method is time consuming and not very efficient. Dr. Lothar Ley, the chief professor of experimental physics at Erlangen-Nuremberg University, and his research team proposed another method of doping: precipitation of C60 molecules on the surface of hydrogen-saturated diamonds .
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