Synthesis of nanoparticles in carbon arc: measurements and modeling
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Research Letter
Synthesis of nanoparticles in carbon arc: measurements and modeling Shurik Yatom, Alexander Khrabry, James Mitrani*, Andrei Khodak, Igor Kaganovich, Vladislav Vekselman, Brent Stratton, and Yevgeny Raitses, Princeton Plasma Physics Laboratory, Princeton University, NJ 08540, USA Address all correspondence to Shurik Yatom at [email protected] (Received 17 February 2018; accepted 25 April 2018)
Abstract This work presents a study of the region of nanoparticle growth in an atmospheric pressure carbon arc. The nanoparticles are detected using the planar laser-induced incandescence technique. The measurements revealed large clouds of nanoparticles in the arc periphery bordering the region with a high density of diatomic carbon molecules. Two-dimensional computational fluid dynamic simulations of the arc combined with thermodynamic modeling show that this is due to the interplay of the condensation of carbon molecular species and the convection flow pattern. These results show that the nanoparticles are formed in the colder, peripheral regions of the arc and describe the parameters necessary for coagulation.
Introduction In recent decades, nanomaterials have been extensively studied by many scientific and engineering communities. The unique optical, electronic, and mechanical properties of these materials are very attractive for a variety of potential applications[1–5]; thus, efficient pathways for the production and modification of nanomaterials are of great interest. Synthesis of nanomaterials, referred to below as nanosynthesis, facilitated by plasma sources has become a standard technique for nanomaterial production.[6–8] Some nanomaterials can only be synthesized with plasma, and for some nanomaterials, plasma synthesis is favored due to industrial scale yield, better selectivity, and improved material characteristics.[9] The plasma arc is a widely used source for producing nanoparticles,[10,11] and carbon arc is utilized for making a variety of carbon nanomaterials including fullerenes, carbon nanotubes, nanohorns, nanofibers, and graphene.[12–21] In the arc, single-walled nanotubes, nanoparticles, and nanohorns are synthesized, while in flight in the gas phase, as opposed to surface growth in chemical vapor deposition. Gas phase synthesis also occurs in laser ablation experiments[22,23]; however, arc synthesis is a less expensive method and also has a significantly higher yield. Unfortunately, the growth mechanism of nanostructures in plasma and gas phases is still poorly understood on both the microscopic and atomistic levels due to the inability to monitor key steps in the synthesis processes, including nucleation and growth. Most previous understanding in this area comes from post-growth, ex situ evaluation of the nanostructures, nanoparticles, and the attached impurities
* Current address: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
using various laser and x-ray spectroscopic techniques and high-resolution electron microscopy,[24–26] together with a trial and error experimental
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