Three-Dimensional Centimeter-Sized Colloidal Silica Crystals Formed by Addition of Base

Three-dimensional (3D) centimeter-sized colloidal crystals can be spontaneously formed simply by dropping a NaOH solution (10 mM, ∼10 μL) into an aqueous dispersion of dilute charged colloidal silica (particle diameter 110 nm, particle volume fraction φ = 0.023, 3−4 mL). The charge number of the sil...

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Bibliographic Details
Published in:Langmuir 2006-08, Vol.22 (18), p.7936-7941
Main Authors: Wakabayashi, Nao, Yamanaka, Junpei, Murai, Masako, Ito, Kensaku, Sawada, Tsutomu, Yonese, Masakastu
Format: Article
Language:English
Subjects:
Chemistry
Colloidal state and disperse state
Colloids
Crystallization
Exact sciences and technology
General and physical chemistry
Imaging, Three-Dimensional
Ions - chemistry
Physical and chemical studies. Granulometry. Electrokinetic phenomena
Silicon Dioxide - chemistry
Sodium Hydroxide - chemistry
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Summary:Three-dimensional (3D) centimeter-sized colloidal crystals can be spontaneously formed simply by dropping a NaOH solution (10 mM, ∼10 μL) into an aqueous dispersion of dilute charged colloidal silica (particle diameter 110 nm, particle volume fraction φ = 0.023, 3−4 mL). The charge number of the silica particle increases with pH. Upon adding the NaOH solution, first, sub-millimeter-sized polycrystals are formed in the upper part of the sample due to charge-induced crystallization. The local φ value in the crystal region becomes nonuniform. The crystals with a high φ value accumulate at the bottom of the cell and then grow upward as columnar crystals. The crystal widths increase discontinuously with the growth, and in some cases, 3D centimeter-sized crystals are formed. The centimeter-sized crystals are also obtainable by the controlled diffusion of the base from its dilute reservoir. The present findings may prove valuable in the fabrication of large 3D single-crystalline photonic materials.
ISSN:0743-7463
1520-5827
DOI:10.1021/la0607959