Controlled Synthesis of Sub-Five-Nanometer Diamond Particles

Diamond nanoparticles in the sub-five-nanometer size regime are crucial for several emerging technologies including subcellular imaging, quantum information processing, and drug delivery. State-of-the-art methods to produce nanodiamonds include mechanical grinding of bulk crystals, decomposition of hydrocarbon molecules, and detonation of explosives. However, no existing technique is capable of precise size control in the sub-five-nanometer regime.<br/>Here we describe a method for controlled synthesis of nanodiamond with 2-5 nm diameter. The key innovation lies in the utilization of metal carbide nanoparticles as carbon sources. The reaction between these metal carbides with metal oxides under high-pressure-high-temperature conditions yields diamond nanoparticles with &lt;5 nm diameter, uniform size, and high crystallinity. The size of the nanodiamond is precisely tuned by the nanostructured carbon precursor. Chemical doping of the precursor allows controlled incorporation of functional defects, enabling these nanodiamonds for key applications as bio-compatible high-resolution fluorescent markers, storage bits for quantum information processing, photon and electron sources as well as vehicles for targeted drug delivery. &lt;!--![endif]----&gt;