Materials Literature
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Spiraling into control: A finite linear arrangement of four magnetically coupled copper(II) centers has been generated within a triple-stranded helical motif that was formed through a strict self-assembly process between a single octadentate ligand and CuII ions (see picture). This approach opens the way to constructi…
Bi 4−x La x Ti 3 O 12 materials were synthesized by the sol-gel process and thin films were prepared on Pt (i.e., Pt/TiO2/SiO2/Si) substrate by spin coating. Structural properties of the films were examined by x-ray diffraction and Raman spectroscopy. Dielectric and ferroelectric response was studied for 0.63-μm-thick…
If a polycrystalline sample exhibits preferred orientation, the relative peak intensities in the powder diffraction pattern deviate from the intrinsic relative diffraction intensities, and can cause major difficulties in attempts to determine structural information from the powder diffraction pattern. To circumvent th…
AlGaAs-based superlattice microcoolers are demonstrated. Maximum cooling temperatures of 0.8 °C and 2 °C were obtained at 25 °C and 100 °C, respectively, from 60 μm×60 μm devices with 100 period Al0.10Ga0.90As/Al0.20Ga0.80As n-type superlattice thermal barriers. These devices may be useful for in situ cooling of GaAs-…
Described are the successful, selective crystallization and characterization of one (δ-form) of the metastable polymorphs of (±)-[2-[4-(3-ethoxy-2-hydroxypropoxy)phenylcarbamoyl]ethyl]dimethylsulfonium p -toluenesulfonate ( 1a ), which is assumed to exist as a transient key-intermediate crystalline phase relevant to t…
Ex situ soft X-ray absorption spectroscopy (SXAS) and X-ray photoelectron spectroscopy (XPS) were used to study the redox behavior of sodium-containing vanadium oxide (Na−VO x ) nanotubes in a rechargeable Li battery context. This nanotubular material consists of scroll-like layers of vanadium oxide separated by struc…
The properties of cellulose materials are dependent on interactions between and within the cellulose chains. To investigate the deformation behavior of cellulose and its relation to molecular straining, sheets with fibers oriented preferably in one direction were studied by dynamic FT-IR spectroscopy. Celluloses with…
In this letter, we report on fabrication and luminescent properties of phosphor powders and thin films of Eu3+ doped alumina Al2O3. The powders were fabricated by combustion synthesis process at a low temperature, 280 °C and showed strong photoluminescent and cathodoluminescent emissions. Powders of Eu3+ doped Al2O3 o…
Porous materials with nanometer-scale structure are important in a wide variety of applications including electronics, photonics, biomedicine, and chemistry. Recent interest focuses on understanding and controlling the properties of these materials. Here we demonstrate porous silicon interference filters, deposited in…
Ordered mesoporous carbons (OMCs) were synthesized in the pore system of SBA-15 aluminosilicates with different Si/Al ratios ranging from 5 to 80. Nitrogen adsorption was used to characterize the pore structure of the aluminosilicates and of the OMCs, whereas the OMC surface chemistry was studied by X-ray photoelectro…
We report on a chirality-induced polarization effect in a planar subwavelength metallic nanograting. We demonstrate that the grating rotates the polarization at normal incidence. Because of the fourfold rotation symmetry, the effect does not depend on the incident beam polarization, but resembles optical activity in i…
The phonon dispersions and atomic displacements for single-wall carbon nanotubes of arbitrary chirality are calculated. The full symmetry is implemented. The approach is based on the force constants of graphene, with the symmetry imposed modifications providing the twisting acoustic mode exactly. The functional depend…
Preserving the structural and functional integrity of interfaces and inhibiting deleterious chemical interactions are critical for realizing devices with sub-50 nm thin films and nanoscale units. Here, we demonstrate that ∼0.7-nm-thick self-assembled monolayers (SAMs) comprising mercapto-propyl-tri-methoxy-silane (MPT…
In this study, a series of nanoindentations was made on NiTi shape memory alloy thin films at millinewton loads with a Berkovich indenter. Mapping of the indentation topography using atomic force microscopy reveals direct evidence that the thermally induced martensitic transformation of these films allows for partial…
We have measured the optical conductivity of single crystal ${\mathrm{L}\mathrm{u}\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$ from 10 to $45\text{ }000\text{ }\text{ }{\mathrm{c}\mathrm{m}}^{\ensuremath{-}1}$ at temperatures between 4 and 300 K. A symmetry allowed on-site Mn $d\mathrm{\text{\ensuremath{-}}}d$ transition near…
The electrical activity of nitrogen as an acceptor in ZnO has been investigated in two ways. First, nitrogen was introduced by means of diallylamine during metalorganic vapor phase epitaxy (MOVPE) yielding incorporation of nitrogen in the range 1016–1021 cm−3. This led to significant compensation of the natural donors…
The atomic processes associated with energy storage and release in irradiated graphite have long been subject to untested speculation. We examine structures and recombination routes for interstitial-vacancy (I-V) pairs in graphite. Interaction results in the formation of a new metastable defect (an intimate I-V pair)…
This letter reports on the pressure dependence of the optical absorption edge of ZnO in the rock-salt phase, up to 20 GPa. Both vapor-phase monocrystals and pulsed-laser-deposition thin films on mica have been investigated. Rock-salt ZnO is shown to be an indirect semiconductor with a band gap of 2.45±0.15 eV, whose p…
Große Hohlräume (10–12.3 nm) werden während der Synthese von mesoporösem kubischem SiO2 durch Blockcopolymer-Template ausgefüllt. Die Größe der Hohlraumeingänge kann zwischen 4 und 9 nm variiert und durch Stickstoffsorption sowie anhand von Goldrepliken ermittelt werden. Diese offenen dreidimensionalen Mesostrukturen…
We report on how the mirror reaction method can be used to prepare silver films with well controlled grain sizes in the range that is known to be ideal for surface plasmon experiments in the visible region of the spectrum. We characterize the morphology of the silver films by atomic force microscopy and their optical…