Detonation nanodiamond

Lore & Background

Detonation nanodiamond is produced by detonating an oxygen-deficient mixture of TNT and RDX in a closed chamber. The diamond particles, about 5 nm in diameter, form at the detonation wave front within microseconds. The yield crucially depends on the cooling medium's heat capacity; water, air, or CO₂ can be used, with higher cooling capacity yielding more diamond, typically in the range of 10% to 50%.

After synthesis, diamond is extracted from the soot by boiling in acid under high temperature and pressure for one to two days. This removes metal contamination from the chamber and non-diamond carbon. The grains are structurally imperfect, with multiple twins as major defects, and have a diamond cubic lattice. Despite the nitrogen-rich explosive source, paramagnetic nitrogen concentration inside the diamond grains can vary, often reaching higher levels depending on synthesis conditions.

The nanodiamond grains spontaneously form micrometer-sized clusters due to strong adhesion. Their large relative surface area causes them to attach water and hydrocarbon molecules from the air, though a clean surface can be obtained with proper handling.

Reader's Guide

Detonation nanodiamond represents a significant class of nanomaterials, notable for its production method using conventional explosives. Its importance lies in the combination of diamond hardness and nanoscale size, enabling applications in lapping and polishing, as additives to engine oils and electroplating electrolytes, as dry lubricants for metal wire drawing, and as reinforcing or thermal fillers for plastics and rubber. In medicine, nanodiamond clusters can shuttle chemotherapy drugs to cancer cells, releasing them only at the target and reducing damage to healthy cells; the diamonds themselves do not induce inflammation. The synthesis method also gained public attention when the SKN Company received the Ig Nobel Peace Prize in 2012 for converting old Russian ammunition into nanodiamonds. Alternative synthesis methods exist, including ultrasonic cavitation of graphite in organic liquid, laser irradiation of graphite, and a microplasma process that forms nanodiamonds directly from gas without a surface. The field continues to explore the balance between yield, purity, and cost.

Did You Know?

• The diamond yield after detonation typically ranges from 10% to 50% depending on the cooling capacity of the medium.
• Paramagnetic nitrogen concentration inside detonation nanodiamond grains can vary and is often higher than one part per million, depending on synthesis conditions.
• In 2012 the SKN Company was awarded the Ig Nobel Peace Prize for converting old Russian ammunition into nanodiamonds.
• Nanodiamond clusters can shuttle chemotherapy drugs to cells and do not induce inflammation after release.