This invention provides a method for preparing transparent
polycrystalline diamond nanoparticles at low temperatures, comprising the following steps: S1: Mixing: Using
hydrogen-
modified carbon nanospheres as raw materials, the raw materials are mixed after removing
moisture and impurities; S2: Pressing: The mixed raw materials are pressed into cylindrical shapes according to the size of the synthesis chamber using a
hydraulic press; S3:
Assembly: The cylindrical raw materials are placed into a heating container and then assembled in the synthesis chamber; S4: Synthesis: The pressure is controlled at 9.0-15 GPa, the temperature at 1250-2300℃, and the
holding time is 1-15 min, to synthesize the raw materials assembled in step S3 to obtain the product; S5: Cooling and depressurization: After the product synthesized in step S4 is cooled and depressurized, transparent
polycrystalline diamond nanoparticles are obtained. This invention provides a low-cost and relatively simple method for preparing transparent
polycrystalline diamond nanoparticles at low temperatures, which has high commercial and promotional value.