Defect Elimination in Nanoscale Materials


Generating defect-free nanotubes or nanowires with superior mechanical, thermal, and electrical properties for devices such as MEMS/NEMS, ICs, and resistors, as well as for ultimate-strength materials Creating sophisticated heterojunctions in a MWNT by refining specific sections and not others


Allows control of nanotube diameter, length, defect concentration, and thermal and electrical conductivity Improves the quality of MWNTs and nanowires Easily scalable, low temperature process


Bulk synthesis techniques have been unable to offer fully controlled growth of multiwall carbon nanotubes (MWNT) and other nanomaterials such as nanowires, yet this type of quality control will be required for many commercial nanomaterial applications. Alex Zettl and his team at Berkeley Lab have developed a low temperature, scalable method of refining MWNTs to produce nanotubes with superior mechanical and electrical properties and to generate heterojunctions within the tubes which serve as schottky interfaces or p/n junctions.

In the Berkeley Lab refinement process, a carbon-loaded catalyst particle is either incorporated into each original MWNT via the original synthesis process or inserted later. An electrical current is passed through the tubes, driving the melted catalyst beads down the tube. The catalyst bead consumes and re-forms the original low-grade nanotube as it migrates, ejecting a higher quality MWNT from the trailing end. Because the carbon particles in the catalyst are replenished, defect-free nanotubes as long as the original tube can be generated. The electrical current determines the speed of the nanotube formation or refinement, which in turn allows control of the tube’s defect concentration, and therefore, its electrical, thermal, and mechanical properties. The catalysts can be left on the nanotube or removed through acid etching.

Type of Offer: Licensing

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