研究目的
Investigating the synthesis of monolithic mesoporous nanopolycrystalline diamond from periodic mesoporous carbon and the pressure-dependence of its porosity.
研究成果
The synthesis of transparent, mesoporous, nanopolycrystalline diamond monoliths from periodic mesoporous SBA-15 type carbon at pressures between 15 and 21 GPa and a temperature of 1300 °C was successful. The porosity and surface area of nanopolycrystalline diamond increase with increasing synthesis pressure, which may be due to the earlier onset of diamond nucleation at higher pressure.
研究不足
The study is limited to the synthesis conditions of 15 to 21 GPa and a temperature of 1300 °C. The minimal pressure required for the formation of nanopolycrystalline diamond and the dependence of pressure on the porosity were not fully explored.
1：Experimental Design and Method Selection:
The synthesis of nanopolycrystalline diamond was performed using a periodic mesoporous carbon material with cylindrical pores (SBA-15 type) as a precursor under high-pressure high-temperature conditions.
2：Sample Selection and Data Sources:
The precursor SBA-15 type periodic mesoporous carbon material has a pore size of
3：3 nm, a BET surface area of ~650 m2 g?1 and a pore volume of 6 cm3/g. List of Experimental Equipment and Materials:
High-pressure experiments were performed using an 8/3 cell assembly in a multianvil apparatus. The samples were compressed to 15, 18, and 21 GPa and heated at temperatures of 1300 °C for 180 min respectively.
4：Experimental Procedures and Operational Workflow:
The sample was compressed to the desired pressure at a rate of 2 GPa/h at room temperature and then heated to the final temperature at a rate of 50 °C/min. After the final temperature was reached, the temperature was kept constant for 3 h. Then, the pressure was released at a rate of 2 GPa/h.
5：Data Analysis Methods:
The synthesized diamond was characterized with X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The porosity was quantified with 3-D electron tomography.
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