"NANOPARTICLE AND NANOTUBE PRODUCTION BY A NOVEL LASER-LIQUID-SOLID INTERACTION TECHNIQUE"

Inventor: J. Singh

ARL Inv. Disc. No. 648

Issued U.S. Patent Nos. 5,770,126 & 6,068,800

Nanoparticles (1-100 nm diam.) are used in a wide range of biomedical, catalytic, magnetic, electronic, and structural applications. Conventional methods for producing nanoparticles include mechanical milling, spray pyrolysis, chemical precipitation, and vapor-phase synthesis. Each of these methods has shortcomings associated with the control of particle size and morphology, material contamination, excessive particle agglomeration, and hazardous chemical wastes.

Dr. Singh has developed an alternative method for the production of nanoparticles that overcomes many of the shortcomings of the conventional methods. He uses a pulsed or continuous laser to locally heat a metallic substrate that is immersed in a liquid, chemical precursor. The resulting laser-liquid-solid interaction (LLSI) is an unprecedented process for producing nanoparticles and nanotubes. The synthesis rate and morphology of the nanoparticles are dependent upon four major process variables: (1) laser wavelength, (2) precursor composition and concentration, (3) laser energy, and (4) interaction time.

Manipulating these variables has led to the production of nanoparticles of silver, nickel and nickel oxide, immiscible alloys (such as silver-nickel), and metallic oxides (cobalt, iron, vanadium).

Major advantages of this technique include:

control of particle size and clusters, from 1 nm to 100 nm

high quality and purity of particles

synthesis rates of 2-3 grams/hour

flexibility in terms of scale and particles composition

environmentally compliant

Laser power of 300 W is sufficient to drive the process allowing the possibility of using a single high power laser and beam splitters to increase production and reduce costs.