Formation and Properties of Aerocolloidal TiO2-Coated Microspheres Produced by Alkoxide Droplet Reaction

Li, Wanguano; Rassat, Scot D.; Foss, Willard R.; Davis, E. James

doi:10.1006/jcis.1994.1039

Cited by 31 publications

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“…There have been a number of contact and non-contact studies on core-shell systems reported in the literature, e.g. [15][16][17][18][19][20][21][22][23][24][25][26][27] The most relevant study is that by Hightower et al, 18 who trapped glass microspheres of B4 mm radius in vacuum using a quadrupole trap. The glass beads were coated in glycerine and the scattered light intensity was recorded at a fixed angle during the evaporation of glycerine.…”

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Atmospherically relevant core–shell aerosol studied using optical trapping and Mie scattering

2015

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Atmospherically relevant core–shell aerosol studied using optical trapping and Mie scattering

2015

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“…In the present system titanium(1V) ethoxide reacts with water vapor much faster than TEOS; as a consequence a titanium (hydrous) oxide shell is produced first, which slows down the overall process and especially the formation of silica. Recently, Davis and his associates (Li et al, 1994) studied the hydrolysis of a single electrodynamically levitated microdroplet of Ti(OEt), with water vapor. They were able to demonstrate that a TiO, shell is formed, which may eventually even stop the reaction, resulting in hollow particles.…”

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Preparation of Uniform Colloidal Dispersions by Chemical Reactions in Aerosols. VI. Silica/Titania Composite Particles

Matijević

Zhong

Partch

1995

Aerosol Science and Technology

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Spherical silica/titania particles were prepared by nebulizing with a nozzle liquid mixtures of tetraethyl orthosilicate iTEOS) and titaniumiIV) ethoxide [TiiOEt),] and contacting the resulting droplets with water vapor. The size distribution of the liquid aerosols was improved by mechanically eliminating the larger droplets and by the evaporation and condensation of the remaining droplets in the presence of AgCl nuclei introduced with the carrier gas. The composition of the resulting solids differed from that expected from the original liquids. Furthermore, the particles were not internally homogeneous; the surface layers contained a higher molar ratio of titania than the bulk. The electrokinetic data corroborated the surface composition. On calcination at 700°C, the titania component crystallized to anatase in the originally amorphous particles.

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“…The analog dot map is a Zdimensional visual representation of the spatial distribution of an element across the surface of a sample. The formation of shells by this electrodispersion precipitation process is closely related to the formation of coated-and porous shell-aerosol particles by simultaneous diffusion and chemical reaction (22)(23)(24)(25). It is well known in aerosol processes that the reaction between a reactive gas and an aeorsol droplet leads to the formation of spherical shells when the reaction rate is fast compared with diffusion within the droplet and when the solubility of the reaction product is low in the solution.…”

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Porous Spherical Shells and Microspheres by Electrodispersion Precipitation

et al. 1994

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Pulsed electric fields have been used to enhance the dispersion of aqueous metal (Zr and Al) salt solutions from a nozzle and into a nonconducting liquid continuous phase that is immiscible with the aqueous phase. The diameter of the resulting microdroplets ranged in size from approximately 0.1 to 10 pm. Precipitation of hydrous metal oxides occurred as ammonia, which was dissolved in varying amounts in the continuous phase, diffused into the aqueous microdroplets. Spherical shells were formed at higher ammonia concentrations and microspheres were produced at lower ammonia concentrations. Upon drying, dimples appeared in the particles that were synthesized at higher ammonia concentrations. The latter result accords with the well known fact that under certain conditions spherical shells collapse when a fluid is extracted from the core of the particle.No dimples were observed in the microspheres that were produced at lower ammonia concentrations. Analog X-ray dot maps for aluminum and zirconium were done to determine the spatial distribution of each metal in the particles.

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Formation and Properties of Aerocolloidal TiO2-Coated Microspheres Produced by Alkoxide Droplet Reaction

Cited by 31 publications

References 0 publications

Atmospherically relevant core–shell aerosol studied using optical trapping and Mie scattering

Atmospherically relevant core–shell aerosol studied using optical trapping and Mie scattering

Preparation of Uniform Colloidal Dispersions by Chemical Reactions in Aerosols. VI. Silica/Titania Composite Particles

Porous Spherical Shells and Microspheres by Electrodispersion Precipitation

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