Submicrosecond Aggregation during Detonation Synthesis of Nanodiamond

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Physics

Background:

• Detonation nanodiamonds (DND) tend to form aggregates, diminishing their nanoscale properties and necessitating post-processing.
• The kinetics and mechanisms of DND aggregation remain experimentally uncharacterized, hindering strategies for aggregation control.

Purpose of the Study:

• To experimentally determine the time scales and mechanisms of detonation nanodiamond aggregation.
• To provide insights into controlling DND properties by understanding early-stage aggregation.

Main Methods:

• Time-resolved small-angle X-ray scattering (TR-SAXS) was employed.
• SAXS measurements were conducted in situ during high-explosive detonations producing carbon nanomaterials.

Main Results:

• DND aggregation into low fractal dimension structures was observed as early as 0.1 microseconds post-detonation.
• A distinct scattering signal, indicative of graphitic products, was observed concurrently.
• Explosives producing nano-onions showed no hierarchical scattering within 10 microseconds, suggesting delayed aggregation.

Conclusions:

• DND aggregation occurs on very short timescales, comparable to particle formation during detonation.
• The findings highlight the rapid nature of DND aggregation and its dependence on the carbon phase formed.
• This research provides a foundation for developing methods to mitigate DND aggregation.