Materials Literature
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Temperature induced structural phase transitions in the lead doped Aurivillius oxides Ba 1− x Pb x Bi 2 Nb 2 O 9 ( x = 0.375,0.625) are explored using powder neutron diffraction methods in the context of the pure parent compounds, PbBi 2 Nb 2 O 9 and BaBi 2 Nb 2 O 9 . At both lead concentrations the system is found to…
The capacity of intentionally created defects to act as possible channels for oxygen incorporation into the subsurface region has been studied by means of thermal desorption spectroscopy and ultraviolet photoelectron spectroscopy (21.2 eV). Thermal-energy atom scattering has been applied to determine the overall surfa…
Strain sensing characteristic of carbon nanotubes has been established in the past at nanoscale. In this study, it is shown that the carbon nanotube film sensors, made up of randomly oriented carbon nanotubes, can be used as strain sensors at macro level. A nearly linear trend between the change in voltage, measured u…
An analytical method to estimate the thickness of the interface between two phases from small-angle scattering (SAS) data has been developed using Porod's law modified by a triangular smoothing function. The convolution with a `top-hat' function describing a sharp density profile results in a semi-sigmoidal density pr…
Detailed strain relaxation studies of epitaxial magnetite, Fe 3 O 4 , films on MgO(100) substrates grown by magnetron sputtering reveal the accommodation of strain up to 600 nm thickness, a thickness far above the critical thickness ( t c ) predicted by theoretical models. The results are in agreement with the suggest…
The Rietveld method is the most straightforward and statistically correct approach for the refinement of crystal structure parameters from powder diffraction data. The equivalent two-stage approach, involving the refinement of structural parameters based on integrated intensities extracted using the Pawley method, is…
An analysis of simulated framework structures based on the rigid-unit model quantifies the distortion of polyhedra from their ideal geometric forms and decomposes the motions of the structure into components of rigid-unit displacement, rigid-unit rotation and distortion. Case studies analysing the behaviour of quartz…
Diacetylene-containing polycarboranylenesiloxane copolymers were prepared by two different methods to yield either alternating or block copolymers with respect to the diacetylene distribution along the backbone. With each method, a set of copolymers was prepared with trisiloxane:carborane:diacetylene molar ratios of 1…
The electronic structure of a monolayer-protected gold cluster, [Au 13 (SCH 3 ) 8 ] 3+, has been investigated by performing density functional calculations. The cluster has a characteristic structure with O h molecular symmetry, and eight (111) facets of a centered cuboctahedral Au 13 core cluster are fully passivated…
Atomically well-defined discrete fully coordinated spherical and elongated nanocages constructed from SiO 2 are shown, via density functional calculations, to be structurally stable. Generally the spherical nanocages are energetically preferred over the elongated nanocages. With increasing size, both types of nanostru…
Photochemical reduction of several 4-picolyl- and N-methyl-4-picolinium esters was examined using product analysis, laser flash photolysis, and fluorescence quenching. It is demonstrated that the radical (anions) formed in these reactions readily fragment to yield a carboxylic acid and a 4-pyridylmethyl radical interm…
Using the Bingel reaction as a model for side-wall functionalization of single-walled carbon nanotubes, we report the discovery of highly regular, long-distance (several nanometer) patterns and examine the conditions for the occurrence of such patterns, possibly due to long-range induced reactivity. Varying periodicit…
Novel quaternary rare-earth copper sulfides EuRCuS3 (R = Y, Gd–Lu excluding Ho, Er) have been investigated by means of x-ray diffraction, magnetic susceptibility, magnetization, and specific heat measurements. These compounds crystallize in the Eu2CuS3-type structure for R = Y, Gd–Dy and in the KZrCuS3-type structure…
A novel donor-bridge-acceptor system has been synthesized by covalently linking a p-phenylene vinylene oligomer (OPV) and a perylene diimid (PERY) at opposite ends of a m-phenylene ethynylene oligomer (FOLD) of twelve phenyl rings, containing nonpolar (S)-3,7-dimethyl-1-octanoxy side chains. For comparison, model comp…
Hybrid organosilica mesoporous materials with pores of ordered three-dimensional hexagonal structure were prepared by the hydrolysis and co-condensation of 1,2-bis(triethoxysilyl)ethane with various concentrations of a surfactant as structure directing agents. The materials had high pore volume of 1-1.5 mL/g and high…
Simultaneous measurements of microscopic infrared (MicIR) dichroism, mesoscale deformation, and macroscopic stress during uniaxial stretching are made to four microphase-separated poly(ether- block -amide) (PEBA) films quenched form melt. Before the onset of microstructural alterations, poly(tetramethylene oxide) (PTM…
A molecular dynamics simulation of ultrathin gold nanowires for tensile behaviour has been carried out. Ultrathin nanowires, unlike the bulk FCC structure, have a multi-shell helical structure. This work compares the mechanical properties of the 7-1 multi-shell helical structure with those of the FCC structure. The re…
Oriented lamellar nanocomposites formed of alternating organic and inorganic layers were prepared by evaporation-induced self-assembly and studied by small-angle X-ray scattering in symmetrical and asymmetrical reflection. Analytical expressions were used for a quantitative fit of the experimental data. The fitting pr…
An increase of the X-ray diffraction line broadening with increasing diffraction angle was observed experimentally in nanocrystalline thin films. Such a change of the line width is usually related to the microstrain in the sample, which, however, contradicts the assumptions that the microstrain is relatively low in na…
Cationic catalysis using simple carboxylic acids to combine the ring-opening polymerization of ε-caprolactone and the regioselective acylation of carbohydrates has been investigated. l -Lactic acid catalyzed the acylation of methyl β- d -glucopyranoside and sucrose with ε-caprolactone in high yield by bulk polymerizat…