Air Oxidation Disaggregates the Nanodiamond Powder

The surface modification to nanodiamond (ND) powder was performed through air oxidation to avoid the nanoscale particle aggregation of suspension. The ND powders treated for varied oxidation duration were analyzed by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and laser particle size analysis. The results show that the best effect was achieved when the ND powder was subjected to air oxidation at 450°C for 12 h. A ND suspension was prepared using the ND powder oxidized in air for 12 h, resulting in an average particle size of 11.8 nm. This ND suspension was then used for seed crystal formation on silicon substrates via ultrasonic treatment, with a seeding density of 10¹¹ achieved.