AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
The Sintering Rate of Aerosol Nanoparticles
Beat Buesser, Arto Groehn, SOTIRIS E. PRATSINIS, ETH Zurich
Abstract Number: 123 Working Group: Nanoparticles and Materials Synthesis
Abstract The basic sintering mechanism and growth rate of aerosol nanoparticles is investigated by accelerated molecular dynamics. Primarily, the sintering or coalescence of TiO2 nanoparticles, the dominant photocatalytic material and a promising candidate for photovoltaics and organic vapor sensors, is elucidated by monitoring the detailed motion of Ti and O atoms with accelerated molecular dynamics. It is shown how rutile nanoparticles realign themselves during sintering to match their fusing lattice plains (1). It is revealed that sintering by surface diffusion dominates the growth of such particles with minimal displacement of inner atoms (sintering by grain boundary diffusion). This is in stark contrast with classical ceramics where compacts of particles are used in sintering studies. In addition, a long-standing question on the significance and sequence of these two sintering mechanisms for TiO2 is resolved contributing a quantitative expression for the accelerated sintering rate of nanoparticles that beautifully converges to that of much larger ones (2,3) at only about 5 nm instead of 10 or 20 nm. This expression can be readily used in phenomenological sintering models for the design, scale-up and optimization of gas-phase manufacture of nanoparticles. Furthermore it is extended to metal nanoparticles and multiparticle structures exploring the role of geometry in deciphering sintering mechanisms and extracting their sintering or coalescence rates.
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[3] T. Seto, M. Shimada, K. Okuyama, Evaluation of sintering of nanometer-sized titania using aerosol method. Aerosol Sci. Technol. 23, 183 (1995).