The influence of a convection field on the growth of high-quality diamond under high-temperature, high-pressure conditions using catalyst systems with different viscosities

In this work, the effect of catalyst viscosity on diamond growth was studied by simulating and analyzing the catalyst convection field in a diamond synthesis chamber in different viscous catalyst systems. The results showed that the low-viscosity catalyst had a high convection velocity, fast carbon flow, and large crystal growth volume, but it easily produced defects during long growth times. The convection velocity in the high-viscosity catalyst was slow, the precipitation rate of carbon was moderate, and the crystal quality was good. It is suitable for growing high-quality large-sized diamond single crystals. The structural properties of the synthesized samples were characterized by optical microscopy and Raman spectroscopy. The synthesis experiment and simulation results were consistent. In this experiment, a new viscosity concept is proposed to control the quality of diamond crystals, in which the crystal morphology is controlled by adjusting the flow field in the catalyst. This is not limited to controlling the synthesis of crystals with different morphologies by changing the temperature gradient in the diamond synthesis chamber. Therefore, this paper establishes the characteristics of a convection field suitable for the growth of diamond crystals using different viscous catalysts and provides an important theoretical reference for cavity optimization and the design of flow fields for new catalysts.