نتایج جستجو برای: amorphous silica
تعداد نتایج: 61469 فیلتر نتایج به سال:
0009-2614/$ see front matter 2011 Elsevier B.V. A doi:10.1016/j.cplett.2011.06.077 ⇑ Corresponding authors. E-mail addresses: [email protected] (M. uochb.cas.cz (L. Benda), [email protected] (P. Bouř). Fused silica light-scattering properties are important for many industrial and laboratory applications. In this work, ab initio molecular dynamics employing periodic boundary conditions are ...
Grafting reactive molecular complexes on dehydroxylated amorphous silica is a strategy to develop "single-site" heterogeneous catalysts. In general, only the reactivity of isolated silanols is invoked for silica dehydroxylated at 700 °C ([SiO(2-700)]), though ca. 10% of the surface silanols are in fact geminal Q2-silanols. Here we report the reaction of allyltributylstannane with [SiO(2-700)] a...
Self-assembled lamellar silica-surfactant mesophase composites have been prepared with crystal-like ordering in the silica frameworks using a variety of cationic surfactant species under hydrothermal conditions. These materials represent the first mesoscopically ordered composites that have been directly synthesized with structure-directing surfactants yielding highly ordered inorganic framewor...
Freestanding and well-ordered two-dimensional (2D) silica monolayers with tetrahedral (T-silica) and octahedral (O-silica) building blocks are found to be stable by first-principles calculations. T-silica is formed by corner-sharing SiO4 tetrahedrons in a rectangular network, and O-silica consists of edge-sharing SiO6 octahedrons. Moreover, the insulating O-silica is the strongest silica monola...
We report a simple and rapid method for the deposition of amorphous silica onto a gold surface. The method is based on the ability of lysozyme to mediate the formation of silica nanoparticles. A monolayer of lysozyme is deposited via non-specific binding to gold. The lysozyme then mediates the self-assembled formation of a silica monolayer. The silica formation described herein occurs on a surf...
[1] High‐silica materials have been observed on Mars, both from orbit by the CRISM spectrometer and in situ by the Spirit rover at Gusev Crater. These observations potentially imply a wet, geologically active Martian surface. To understand silica formation on Mars, it is useful to study analogous terrestrial silica deposits. We studied silica coatings that occur on the 1974 Kilauea flow in the ...
ZnOfilmswith thickness of 80 nmwere grownbypulsed laser deposition (PLD) onMgO (100) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnOsingle crystalwereperformedby slowpositron implantation spectroscopy (SPIS). Itwas found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreo...
The hydration behaviour of Ca3Al2O6, Ca12Al14O33 and CaAl2O4 with added amorphous silica at 40, 65 and 90 1C has been studied for periods ranging from 1 to 31 days. In hydrated samples crystalline phases like katoite (Ca3Al2(SiO4)3 x(OH)4x) and gibbsite, Al(OH)3, were identified, likewise amorphous phases like Al(OH)x, calcium silicate hydrates, C–S–H, and calcium aluminosilicate hydrates, C–S–...
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