Effect of Buoyant Force and Its Influence on the Process of Growing Diamond by the Excess Pressure Seed Method

In Excess Pressure Seed Method of synthesis diamond, we have observed the phenomenon that crystal seed grew floating up in the melting metal solvent under high-temperature and high-pressure by appropriate designing the composite cavity assembly, designing the way and the location of crystal seed plant and selecting of composite condition. The phenomenon is caused by the difference of specific gravity between metal and carbon. In the experiment, a close relation is shown between the crystal seed floating up phenomenon and the composite condition. An appropriately high temperature and pressure is necessary. The effect of buoyant has some influence on the formation of the diamond polycrystalline and crystal shape in excess pressure seed method.