Materials Literature
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Colloidal ZnSe nanocrystals are coated with a ZnS shell and are investigated by means of time-resolved photoluminescence spectroscopy. These nanocrystals are stable against photooxidation and have photoluminescence quantum efficiencies around 15% even months after the synthesis. Recombination processes are investigate…
Preferentially oriented perovskite-structured Na0.5K0.5NbO3 (NKN) thin films have been deposited on hexagonal Al2O3(011_2) substrates using rf magnetron sputtering of a stoichiometric, high-density, ceramic target. Structural and film surface properties were measured using x-ray diffraction and atomic force microscopy…
A new procedure to directly pattern a luminescent porous silicon substrate by dry‐removal soft lithography is outlined. The ability to transfer a removed microstructure of porous silicon to a free‐standing flexible polymer film is also demonstrated, and by removing strips in orthogonal directions, an array of PSi pill…
The microstructure of distributed electron cyclotron resonance plasma-deposited hydrogenated amorphous carbon films (a-C:H) was investigated using electron diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. Experimental evidence of the existence of transpolyacetylene (TPA) chains in a-C:H fi…
The hydrothermal reaction of V2O5, H2C2O4·2H2O, en, KOH and NiCl2·6H2O gives a new two-dimensional open-framework solid; the extended structure consists of a two-dimensional network formed by the interconnection of each [V18O42Cl] cage to four other neighboring units via six [Ni(en)2]2+ bridging groups.
Laterally aligned carbon nanotubes were synthesized on substrates over iron nanoparticles using chemical vapor deposition. In addition, aligned carbon nanotubes grown vertically and with tilt angle to the substrates were produced, which means that it is possible to grow aligned carbon nanotubes at any angle relative t…
Mesoporous hybrid inorganic–organic silicate films with pendant methyl groups are prepared. With a high organic fraction, these films are hydrophobic, which is important in the fabrication of low‐k dielectrics. The refractive index of layers with smaller organic fraction can be switched reversibly over a large refract…
A promising solution to the environmental instability of semiconducting organic materials is presented. Thin, highly ordered films (see Figure, a scanning probe microscopy image), fibers, and field‐effect transistors (FETs), comprising chain‐structures based on the so‐called Magnus’ green salt, [Pt(NH 3 ) 4 ]‐[PtCl 4…
Uniform, separated BaCrO 4 single‐crystalline nanofibers with high aspect ratio (> 5000, see Figure) can be fabricated at room temperature in aqueous solution using a double hydrophilic block copolymer as structure‐directing agent and introducing colloidal nucleation agents. Such fibers represent a model case for a…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTAn Improved Method To Strip Aluminum from Porous Anodic Alumina FilmsTerry T. Xu, Richard D. Piner, and Rodney S. RuoffView Author Information Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 Cite this: Langmuir 2003, 1…
We conducted impedance spectroscopy measurements on lead zirconate titanate capacitors of varying lateral size from 130×180 μm down to 1×1 μm. We discovered a peak in the impedance response with a frequency that depends on the perimeter of the capacitor with an exponential relationship. Our model for this effect is ba…
We provide existence of a unique smooth solution for a class of one-and two-phase Stefan problems with Gibbs-Thomson correction in arbitrary space dimensions.In addition, it is shown that the moving interface depends analytically on the temporal and spatial variables.Of crucial importance for the analysis is the prope…
Abstract Understanding the molecular alignment of conjugated polymers within thin‐film samples is essential for a complete picture of their optical and transport properties, and hence for the continued development of optoelectronic device applications. We report here on the efficacy of Raman anisotropy measurements as…
Novel carbon nanofibers (see Figure) are synthesized by capillary impregnation of discotic mesophase pitch into nanochannel alumina. Heating and chemical etching produces nanofibers with a unique “orthogonal” arrangement of graphene layers. Unlike conventional nanofibers and ‐tubes, the graphene planes lie transverse…
Non‐destructive readout of an image using IR light on a polymer film containing a photochromic diarylethene was successively carried out. 1,2‐Bis(2‐methyl‐6‐phenyl‐1‐benzothiophen‐3‐yl)hexafluorocyclopentene was found to exhibit a remarkable IR spectral change around 1590 cm –1 upon photoirradiation, as demonstrated i…
We report the self-assembly process of a supramolecular edifice based on the coordination of europium(III) by a ditopic strand L bearing tridentate bis(benzimidazolyl)pyridine subunits. Varying the metal/ligand ratio and using a fruitful combination of electrospray mass spectrometry and absorption spectrophotometry, w…
Abstract We report the self‐assembly and characterization of mesoporous silica thin films with a 3D ordered arrangement of isolated spherical pores. The preparation method was based on solvent‐evaporation induced self‐assembly (EISA), with MTES (CH 3 –Si(OCH 2 CH 3 ) 3 ) as the silica precursor and a polystyrene‐ bloc…
We have synthesized polystyrene shell latex (PSL) surfaces with different initiator concentrations by changing the feed ratio of styrene to 2-(methyl-2‘-chloropropionato)ethyl acrylate ( HEA−Cl) in a series of shell-growth copolymerization reactions. Surfaces were characterized by conductometric titration of saponifie…
A mosaic consisting of pillars of two kinds of metal , gold and nickel, has been deposited on porous alumina substrates. A sequence of barrier layer application, selective penetration of the barrier, and metal deposition can be manipulated to control the arrangement and density of the composites. An array of Au (brigh…
A new technology to pattern surface charges, either negatively or positively, using a standard photolithography process is introduced. A positively charged poly(allylamine hydrochloride) (PAH) layer is coated onto a negatively charged silicon oxide surface by electrostatic self-assembly (ESA). Combined with photolitho…