Aerosol-assisted synthesis of monodisperse single-crystalline α-cristobalite nanospheres.
ABSTRACT Monodisperse single-crystalline α-cristobalite nanospheres have been synthesized by hydrocarbon-pyrolysis-induced carbon deposition on amorphous silica aerosol nanoparticles, devitrification of the coated silica at high temperature, and subsequent carbon removal by oxidation. The nanosphere size can be well controlled by tuning the size of the colloidal silica precursor. Uniform, high-purity nanocrystalline α-cristobalite is important for catalysis, nanocomposites, advanced polishing, and understanding silica nanotoxicology.
SourceAvailable from: Makoto Ogawa[Show abstract] [Hide abstract]
ABSTRACT: This review highlights the current status on the synthesis and applications of mesoporous silica spherical particles. Mesoporous silica spherical particles are expected to be applied in various fields and the properties depend on the size and size distribution. Many researchers have been working on the synthesis of mesoporous silica spherical particles by means of several approaches and a variety of synthetic parameters have been correlated to the nature of the products. The synthetic approaches are categorized into following four; emulsion based approach, formation from a homogeneous solution, aerosol and morphology template. In this review, the preparation and the potential applications of mesoporous silica spherical particles are summarized.Journal of Nanoscience and Nanotechnology 04/2013; 13(4):2483-94. DOI:10.1166/jnn.2013.7423 · 1.34 Impact Factor
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ABSTRACT: Fabrication of monodisperse porous polymeric nanospheres with diameters below 500 nm remains a great challenge, due to serious crosslinking between neighboring nanospheres during pore-making process. Here we show how a versatile hypercrosslinking strategy can be used to prepare monodisperse microporous polystyrene nanospheres (MMPNSs) with diameters as low as ca. 190 nm. In our approach, an unreactive crosslinked PS outer skin as protective layer can be in-situ formed at the very beginning of hypercrosslinking treatment to minimize the undesired inter-sphere crosslinking. The as-prepared MMPNSs with a well-developed microporous network demonstrate unusual multifunctional properties, including remarkable colloidal stability in aqueous solution, good adsorption-release property for drug, and large adsorption capacity toward organic vapors. Surprisingly, MMPNSs can be directly transformed into high-surface-area monodisperse carbon nanospheres with good colloidal stability via a facile hydrothermal-assisted carbonization procedure. These findings provide a new benchmark for fabricating well-defined porous nanospheres with great promise for various applications.Scientific Reports 03/2013; 3:1430. DOI:10.1038/srep01430 · 5.08 Impact Factor
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ABSTRACT: Piezoelectric nanostructured quartz films of high resonance frequencies are needed for microelectronic devices; however, synthesis methods have been frustrated by the inhomogeneous crystal growth, crystal twinning, and loss of nanofeatures upon crystallization. We report the epitaxial growth of nanostructured polycrystalline quartz films on silicon [Si(100)] substrates via the solution deposition and gelation of amorphous silica thin films, followed by thermal treatment. Key to the process is the combined use of either a strontium (Sr(2+)) or barium (Ba(2+)) catalyst with an amphiphilic molecular template. The silica nanostructure constructed by cooperative self-assembly permits homogeneous distribution of the cations, which are responsible for the crystallization of quartz. The low mismatch between the silicon and α-quartz cell parameters selects this particular polymorph, inducing epitaxial growth.Science 05/2013; 340(6134):827-831. DOI:10.1126/science.1232968 · 31.48 Impact Factor