Abstract
We developed a novel technique to synthesize nanodiamond powder through the decomposition of graphitic C3N4under high pressure and high temperature. The nanodiamond obtained by the present method is in an extremely pure form with no sp2carbon contaminations. Individual nanodiamond grains are very uniform in size and virtually monodispersed single crystals. The grain size can be controlled from less than 1 nm to several hundred nanometers by adjusting the heating temperature (and also potentially by controlling pressure) used for the synthesis. The present product requires neither post-surface treatment to remove outer shell made of sp2carbons nor deglomeration and size classification unlike the case for nanodiamond obtained by the conventional TNT detonation method.
Highlights
Nanodiamond powder has been adopted for many industrial uses such as for polishing, coating, lubricant additives, and catalysts due to its excellent thermal and chemical stability combined with the superhard nature [1]
All the nanodiamond samples were obtained through the decomposition of graphitic C3N4 (g-C3N4) at high P-T conditions
Note that there is clearly a space between the white diamond powders compacted in a cylindrical form and the surrounding platinum capsule (Figure 1(a) inset). This opening space is probably derived from the liquid nitrogen that had been formed through the decomposition of g-C3N4 at high temperature but was vaporized and released to the air during decompression
Summary
Nanodiamond powder has been adopted for many industrial uses such as for polishing, coating, lubricant additives, and catalysts due to its excellent thermal and chemical stability combined with the superhard nature [1]. The major commercially available technique for nanodiamond powder synthesis is the trinitrotoluene (TNT) detonation method. In this technique, nanodiamond crystals with grain sizes in nanometric ranges were obtained as a result of incomplete combustion of the explosive (TNT) in a closed container. Ozawa et al [6], for example, demonstrated that mechanical milling using ceramic micro-beads combined with ultrasonic vibration is effective for the deglomeration. Such mechanical milling may result in chemical/physical contamination by the milling media, and deglomeration of detonation nanodiamond particles is still a challenging task [7]
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