The effect of ionic additives on aerosol coagulation

Xiong, Yi; Pratsinis, Sotiris E.; Mastrangelo, S. V. R.

doi:10.1016/0021-9797(92)90301-2

Cited by 59 publications

(24 citation statements)

References 19 publications

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“…3 This is attributed to the attachment of unipolar ions on the particle surface, thus hindering particle collisions and growth, in agreement with data on suppression of soot formation and growth in hydrocarbon flames by ionizing alkali salt solutions. 4 Hardesty and Weinberg 5 found that the primary particle size of flame-made silica was reduced by a factor of 3 with increasing applied electric potential under positive polarity.…”

Section: Corona-assisted Flame Synthesis Of Ultrafine Titania Particlessupporting

confidence: 70%

Corona-assisted flame synthesis of ultrafine titania particles

Vemury

Pratsinis

1995

Applied Physics Letters

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Synthesis of ultrafine titania particles is investigated in a diffusion flame aerosol reactor in the presence of a gaseous electric discharge (corona) created by two needle electrodes. The corona wind flattens the flame and reduces the particle residence time at high temperatures, resulting in smaller primary particle sizes and lower level of crystallinity. Increasing the applied potential from 5 to 8 kV reduces the particle size from 50 to 25 nm and the rutile content from 20 to 8 wt %. Coronas provide a clean and simple technique that facilitates gas phase synthesis of nanosized materials with controlled size and crystallinity.

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Section: Corona-assisted Flame Synthesis Of Ultrafine Titania Particlessupporting

confidence: 70%

Corona-assisted flame synthesis of ultrafine titania particles

Vemury

Pratsinis

1995

Applied Physics Letters

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“…[13] Collisions are then inhibited, resulting in a larger number of small particles with a narrower size distribution. Though this approach is promising for certain systems, the extent of agglomeration control is not well known.…”

Section: Agglomeration Of Flame-synthesized Particlesmentioning

confidence: 99%

A flame process for synthesis of unagglomerated, low-oxygen nanoparticles: Application to Ti and TiB2

Axelbaum

Sastry

DuFaux

et al. 1997

Metall Mater Trans B

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A gas-phase flame process for synthesizing unagglomerated nanoparticles of metals, intermetallics, ceramics, and composites is described. Employing this process, titanium and titanium boride have been synthesized by the vapor-phase reaction of sodium with titanium tetrachloride and a 1:2 mixture of titanium tetrachloride and boron trichloride, respectively. To minimize agglomeration and protect the particles from postflame oxidation, the NaCl by-product is allowed to condense onto the particles in situ, yielding NaCl-encapsulated particles. In this way, stable, unagglomerated Ti and TiB 2 nanoparticles have been produced and the encapsulated powders have been handled in air without oxidation. Particle size has also been varied with the encapsulation process, and titanium particles with mean sizes of 10 and 60 nm have been produced by varying operating conditions. The NaCl has been removed by water washing as well as vacuum annealing. Thermodynamic results show that the sodium/halide process is applicable for synthesis of many materials, with yields approaching 100 pct under a wide range of operating conditions. Similarly, the encapsulation process is generally applicable, making the sodium/halide flame and encapsulation process a viable one for large-scale synthesis of environmentally insensitive nanopowders.

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“…Some of these metal ions preferentially adsorb onto the particle surfaces and give rise to a unipolar or at least an asymmetrical charge on the particles, which hinders particle growth by coagulation. Xiong et al (1992a) developed a simple model to study the effect of ionic additives on aerosol coagulation using Coulomb's law and Maxwell's images method for calculating the electrostatic repulsive forces between unipolarly charged particles. A thermochemical equilibrium calculation was performed to estimate the charging ability of the alkali metals based on their ionization potential.…”

Section: Effect Of Particle Charging On Aerosol Coagulationmentioning

confidence: 99%

Aerosol Processing of Materials

Gurav,

Kodas,

Pluym

et al. 1993

Aerosol Science and Technology

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384

225

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Recent advances in aerosol generation of materials are reviewed. Gas-to-particle and spray processes (spray pyrolysis) for powder generation and various routes for film generation are discussed from the experimental and theoretical perspectives. The range of materials generated by these routes has increased in recent years to include fullerenes and ceramic superconductors. Many metals and various oxide and nonoxide ceramics have also been added to the list of materials generated by gas-phase routes. Established aerosol routes such as vapor condensation have found widespread applications for generation of nanophase materials. The formation of quantum dots via aerosol approaches has also been demonstrated. The theoretical understanding of gas-to-particle conversion routes has advanced to include the finite rate of particle fusion or sintering occurring after collisions of particles. The modeling of spray pyrolysis systems has provided insight into the control of particle morphology and reactor design. In this review, these recent developments in aerosol generation of powders and films via gas-phase and spray routes are discussed with an emphasis on the material chen~istries involved and the synthesis of nanophase materials.

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The effect of ionic additives on aerosol coagulation

Cited by 59 publications

References 19 publications

Corona-assisted flame synthesis of ultrafine titania particles

Corona-assisted flame synthesis of ultrafine titania particles

A flame process for synthesis of unagglomerated, low-oxygen nanoparticles: Application to Ti and TiB2

Aerosol Processing of Materials

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