Laser pyrolysis - a platform technology to produce functional nanoscale materials for a range of applications
S. Chiruvolu, W. Li, M. Ng, K. Du, N.K. Ting, W.E. McGovern, N. Kambe, R. Mosso and K. Drain
NanoGram Corporation, US
nanoparticles, nanomaterials, TiO2, phosphors, high-index nanocomposites, battery, nanocrystalline, CO2 Laser pyrolysis
Nanoscale materials continue to generate ever increasing levels of interest for applications in a broad-range of fields. Concurrently variety of synthesis methods are being explored and developed for the synthesis and production of nanoparticles including sol-gel, mechanical or chemo-mechanical grinding, hydrothermal method, spray and flame Pyrolysis. However, nanoscale materials, especially complex compounds, have not yet attained the status of standard commercial powder materials. Majority of nanomaterials are either only available in sample quantities or are of poor or inconsistent quality (1).
Laser Pyrolysis, which is a gas phase process, has been pioneered and developed as a viable manufacturing platform (NPMTM) by NanoGram Corporation. It has been successfully employed in synthesizing various nanoscale materials including metals, simple and complex metal oxides, carbides, nitrides, rare-earth doped oxides, multi-elemental glasses among others. NPMTM processing routinely produces very high-quality nanoscale particles with high degree of crystallinity, generally spheroidal morphology and exceptionally tight particle size distributions. In this paper we will introduce and describe laser pyrolysis-based NPMTM process as a platform technology to produce nanoscale materials at commercial scales of kg/hr. Nanoscale materials made by laser pyrolysis are currently being developed for a range of product applications such as phosphors in LED encapsulants, high-index fillers for optical polymer composites, cathode materials for lithium ion batteries. Nanomaterials from NPMTM process have already been commercialized in an exceptionally high-rate battery as cathode material for defibrillators batteries (2). In this paper we briefly present the capabilities of NPMTM processing by showing examples complex materials currently being synthesized, and outline the levels of control available to enable functional materials.
Examples will be presented to demonstrate excellent control of application-specific properties of the nanoparticles. These include control of concentration and oxidation state of a rare-earth dopant ion to produce high quantum efficiency phosphors such as BAM, YAG-Ce, control of phase to produce phase pure nanocrystalline rutile or anatase TiO2 for polymer nanocomposites, and complex composition and crystalline structure control for a range of nanocrystalline lithium-ion battery materials. The paper will present the outstanding level of application-specific properties achievable by NPMTM processing.
As a specific example TiO2 can be controlled either in the pure anatase phase or in the anatase-rutile mixed phases. This presentation will discuss the successes achieved in the concurrent control of crystal structure, phase and size by NPMTM process. This puts forth the flexibility of producing TiO2 powders in the anatase and rutile phases at sub-20nm particle size. Also, the high dispersability of the synthesized powders in various solvents is demonstrated and discussed. The switching between the anatase and rutile phases of the particles, and the average particle size can be easily achieved by varying reaction conditions in the laser reaction zone.
Several other examples will be presented to demonstrate the capabilities and versatility of NPMTM processing.
(1)Peter Hubert Lux Research Report December 2004
(2)Dania Ghantous 18th International Seminar & Exhibit on Primary and Secondary Batteries.
March 5-8, 2001. Fort Lauderdale, FL
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Nanotech 2006 Conference Program Abstract