The Effect of Catalyst Shape on Diamond Growth

In this work, we used finite element simulations to study the changes in the temperature field and convection field inside the cavity during diamond growth. The simulations revealed that the temperature around the diamond first decreases and then increases as the diamond grows. This is because diamond has a high thermal conductivity, and as the diamond grows, the diamond absorbs the surrounding heat, causing the temperature around the diamond to decrease. The location of the cylindrical catalyst (CYC) has a higher temperature, and as the diamond grows to a certain height, the diamond transfers the heat from CYC downward, which can cause the temperature at the bottom to rise. We then simulated the convection field during diamond growth and found that the convection velocity of CYC accelerated as the crystal grew. This will speed up the growth of the crystals, but too much speed will degrade the quality of the crystals. We then simulated the variation of the convection and temperature fields of the convex catalyst (COC). We found that the temperature and convection velocity of COC are less affected by the diamond on the cavity compared to the CYC. Moreover, when using COC in growing large-size diamonds, the convection velocity of the catalyst is more stable and it is easier to grow high-quality large single crystals. This work provides some theoretical reference for diamond growth.