Method Produces Fine-Grained Targets

Langley Research Center, Hampton, Virginia

NASA Langley originally developed a Free Electron Laser (FEL) ablation technique to synthesize single-walled carbon nanotubes. FEL provides a vast improvement over other techniques employed to make carbon nanotubes. The nanotubes produced by FEL are very pure, straight, homogenous, and defect-free. Most notable is that these nanotubes can be produced in much larger quantities than by other laser-based techniques.

Now, the scientists have further provided incremental improvement in this technology by creating a recipe and procedure for the inexpensive and simple production of fine-grained targets required for the synthesis of carbon nanotubes using FEL. Previously used targets employed metal powders that did not have a particularly small grain size or small size dispersibility. The targets used here are made of powder forge metals that are both small and dispersible. The targets facilitate a significant cost reduction in the supply of high-quality single-walled carbon nanotubes.

The fine-grained targets are a matrix of a prismatic edge natural flake graphite that produces strong structural pi bonds when pressed at room temperature. The targets have an approximate grain size of 2 microns. The graphite provides a carbon source that is combined with a metal catalyst made of powder forge nickel and powder forge cobalt.

Previously used targets involved pressing and binding targets with Dylon carbon cement. These particles had an approximate 200-micron particle size, which led to large regions of uncatalyzed target. The new metal powders are small (~0.5 micron), highly dispersible, and two orders of magnitude less expensive. The powders are mixed in appropriate quantities and subjected to low-energy ball-milling to ensure mingling. Targets undergo additional preparatory steps including high-pressure processing. The targets are then subjected to a series of ultrafast infrared laser light pulses at a high repetition rate to vaporize the layers of the spinning targets and create a plume of nanotubes.

NASA is actively seeking licensees to commercialize this technology. Please contact NASA’s Licensing Concierge at This email address is being protected from spambots. You need JavaScript enabled to view it. or call us at 202-358-7432 to initiate licensing discussions. Follow this link here for more information.