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Oxide Nanocrystals (oxide + nanocrystal)

Distribution by Scientific Domains
Polymers and Materials Science60%
Chemistry40%

Selected Abstracts

UV-Light-Driven Immobilization of Surface-Functionalized Oxide Nanocrystals onto Silicon,

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2007
E. Fanizza
Abstract TiO2 nanorods (NRs) and ,-Fe2O3 nanocrystals (NCs) passivated with unsaturated long-chain carboxylic acids, namely 10-undecylenic acid (10UDA) and oleic acid (OLEA), are covalently anchored to Si(100) at room temperature by UV-light-driven reaction of hydrogenated silicon with the carbon,carbon double bond (,CC,) moieties of the capping surfactants. The high reactivity of vinyl groups towards Si provides a general tool for attaching particles of both materials via Si,C bonds. Interestingly, TiO2 NRs were efficiently attached to silicon even when capped by OLEA. This latter finding has been explained by a photocatalytic mechanism involving the primary role of hydroxyl radicals that can be generated upon bandgap TiO2 photoexcitation with UV light. The increased oxide coverage achievable on Si opens access to further surface manipulation, as demonstrated by the possibility of depositing an additional film of Au nanoparticles onto TiO2 via TiO2 -catalyzed visible-light-driven reduction of aqueous AuCl4, ions. Extensive morphological and chemical characterization of the obtained NC-functionalized Si substrates is provided to support the effectiveness of proposed photochemical approaches. [source]

Gas Sensors: Room-Temperature Gas Sensing Based on Electron Transfer between Discrete Tin Oxide Nanocrystals and Multiwalled Carbon Nanotubes (Adv. Mater.

ADVANCED MATERIALS, Issue 24 2009
24/2009)
Hybrid nanostructures consisting of multiwalled carbon nanotubes (CNTs) uniformly coated with SnO2 nanocrystals can be used as a novel gas sensing platform, exhibiting high sensitivity to low-concentration gases (NO2, H2, and CO) at room temperature, report Junhong Chen and co-workers on p. 2487. The hybrid nanomaterial provides a new opportunity to engineer sensing devices through electronic transfer between the nanocrystals and the CNT. [source]

From Hollow to Dense Spheres: Control of Dipolar Interactions by Tailoring the Architecture in Colloidal Aggregates of Superparamagnetic Iron Oxide Nanocrystals,

ADVANCED MATERIALS, Issue 6 2004
P. Tartaj
The synthesis of spherical colloidal aggregates (see Figure) of superparamagnetic iron oxide nanocrystals with different packing fractions is reported. Using a mean-field model, the magnitude of dipolar interactions between nanomagnets has been correlated with differences in their assembly. The results could help understanding of the magnetic behavior of magnetic liposomes and hollow capsules, which are promising for drug delivery. [source]

Size-Controlled Synthesis and Optical Properties of Monodisperse Colloidal Magnesium Oxide Nanocrystals,

ANGEWANDTE CHEMIE, Issue 34 2009
Ri Moon Dr.
MgO wird diskret: Monodisperse MgO-Nanokristalle können durch direkte Kolloidalsynthese hergestellt werden (siehe Bild). Der Durchmesser lässt sich durch Zusatz kleiner Wassermengen zum organischen Reaktionsmedium zwischen 2 und 8,nm einstellen. Obwohl Trioctylphosphanoxid bei der Reaktion anwesend ist, sind die gebildeten Nanokristalle in erster Linie mit Benzylether überzogen. Es wird eine blaue Lumineszenz mit annähernd 20,% Quantenausbeute beobachtet. [source]

Antimony-Doped Tin Oxide Nanocrystals: Synthesis and Solubility Behavior in Organic Solvents

CHEMPHYSCHEM, Issue 5 2009
Rafael O. da Silva
Abstract The right mix: SnO2:Sb nanocrystals (NCs) can be solubilized into organic solvents with a suitable solvent/surfactant combination to achieve a stable colloid (see picture). A single synthesis route and different solvent/amphiphilic molecule pairs are used to obtain soluble NC colloids, instead of requiring several syntheses to obtain soluble NCs in different solvents. This work focuses on the nonaqueous synthesis of antimony-doped tin oxide nanocrystals in the size range of 2,6 nm and the investigation of their solubility in organic solvents (CHCl3 and THF) in the presence of amphiphilic molecules (oleic acid and oleylamine). To unravel the underlying processes, a set of molecular dynamics simulations is performed involving the compatibility of oleic acid and oleylamine in mixtures with both CHCl3 and THF. The results show that the method is useful for obtaining the desired oxide, and that the interaction between amphiphilic molecules and solvents can be predicted by molecular dynamics simulations with very good qualitative agreement. [source]