Plasmachemical technology for high-dispersion products

Vissokov, G. P.; Stefanov, B.; Gerasimov, N.; Oliver, D.; Enikov, R.; Vrantchev, A. I.; Balabanova, E; Pirgov, P

doi:10.1007/bf01111897

Cited by 10 publications

(3 citation statements)

References 4 publications

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“…C sca = 24π 3 (ν«") 4 ν 2 |α ν | 2 (5) where α ν = (ε ν -ε")/(ε ν + 2s m ) (6) and ε = m 2 = (n + ik) 1 n m is the refractive index for the matrix, V is the particle volume (4/3πΓ 3 ), α ν is the polarizability of a sphere, and ε ν and s m are the dielectric constants for the particle and the matrix, respectively. Im signifies the imaginary component of the complex expression.…”

Section: Infrared Light Scattering By Particlesmentioning

confidence: 99%

In-Situ Particle Size and Shape Analysis During Flame Synthesis of Nanosize Powders

Farquhanson¹,

Charpenay²,

Ditaranto³

et al. 1997

Synthesis and Characterization of Advanced Materials

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The unique chemical, electromagnetic and mechanical properties of nanosize particles have generated a demand for a supply of uniform and well characterized particles to develop new applications. Although flame synthesis has been successfully scaled up to commercial production of micron and sub-micron particulates, control of nano-particle size, shape, phase composition, and aggregate size is difficult because flame temperature, residence time and precursor loading all influence these parameters. A Fourier transform infrared spectrometer was interfaced to a diffusion flame reactor to measure these parameters during the production of TiO 2 and SiO 2 by oxidation of TiCl 4 and SiCl 4 , respectively. Rayleigh scattering theory was used to generate spectra to match measured infrared absorbance spectra based on particle size, shape and number density. The approach successfully monitored changes in particle size and shape as a function of process conditions. Theoretical spectra matched to in-situ measurements identified shapes, ranging from spheres to needles. These shapes were confirmed by post -process transmission electron microscopy.Recently, nanosize particles (diameters below 100 nm) have demonstrated enhanced properties in a number of applications. For example, ceramic layers formed from nano-particles demonstrate improved adhesion, ductility, and mechanical strength (7). Changes in chemical, physical and mechanical properties compared to bulk materials, such as a lower melting point, are attributed to the relative number of atoms or molecules on the surface of the particle becoming comparable to that inside the particle (7). The predominant methods of preparing these particles are based on aerosol processes, such as flames (2), tube furnaces (3), gas-condensations (¥), thermal plasmas (5), etc., designed to provide sufficient temperature to promote gas-to-particle conversion. However, until now, only flame 170

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Section: Infrared Light Scattering By Particlesmentioning

confidence: 99%

In-Situ Particle Size and Shape Analysis During Flame Synthesis of Nanosize Powders

Farquhanson¹,

Charpenay²,

Ditaranto³

et al. 1997

Synthesis and Characterization of Advanced Materials

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“…Compared to droplet-to-particle or wet chemical processes, it is more difficult to produce multicomponent materials, and special care has to be taken in handling hazardous off-gases and precursors. Examples of these processes include flame [11], hot-wall [12,13], evaporation-condensation [14,15], plasma [16,17], laser [18] and sputtering [19,20].…”

Section: Process Classificationmentioning

confidence: 99%

Aerosol Flame Reactors for the Synthesis of Nanoparticles

Wegner

Pratsinis

2000

KONA

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This paper presents an overview of recent basic research on flame aerosol reactors for the gasphase synthesis of nanoparticles. Emphasis is placed on flame reactor technology as it is widely used in industry for the large-scale manufacture of oxide and carbon nanoparticles. The importance of reactant gas mixing, additives and external electric fields in flame technology is highlighted for the control of product particle properties by affecting the chemistry, temperature and collision histories. Laser-induced fluorescence (L!F), Fourier transform infrared spectroscopy (FTIRJ and thermophoretic sampling are addressed as some of the promising diagnostic tools in flame aerosol research and even for on-line process control. Recent work on aerosol dynamics modeling is presented, and the growing importance of computational fluid dynamics (CFD) aimed at better understanding the particle formation and growth mechanisms in flames is emphasized, focusing on the synthesis of non-aggregated nanoparticles.

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“…Herein we report a morphologically selective synthesis of nanocrystalline aluminum nitride ( nano -AlN) by low-temperature nitridation of nanocrystalline aluminum ( nano -Al) . Particle morphologies are varied from predominately equiaxed to predominately whisker-like, apparently by the presence of vapor-transport species during nitridation.…”

mentioning

confidence: 99%