Materials Literature
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When a chemical reaction such as \(A \rightleftharpoons B\) takes place simultaneously with a macrophase separation, mesoscopic structures similar to the patterns emerging during microphase separation appear. Since in a chemical system we can easily control the concentrations of the two species and reaction rates and…
To date, optical diffraction gratings filled with liquid crystals have not produced high (>50%) diffraction efficiencies in nonzero diffractive orders. Rigorous coupled-wave analysis indicates, however, that very high diffraction efficiencies (99% in single-wavelength polarized illumination) are theoretically feasible…
Alumina samples with different magnesia concentrations between 0.02 and 1 wt% have been sintered and characterized by electron microscopy. Their dielectric properties between 1 kHz and 15 GHz are studied. Different dielectric behaviors are found for different magnesia concentrations. A model based mainly on dipolar re…
InAs(001)-c(8\ifmmode\times\else\texttimes\fi{}2), InSb(001)-c(8\ifmmode\times\else\texttimes\fi{}2), and several reconstructions of GaAs(001) are exposed at room temperature to iodine molecules (${\mathrm{I}}_{2}$). Low-energy electron diffraction (LEED) and synchrotron soft x-ray photoelectron spectroscopy (SXPS) ar…
The electronic structure and the optical properties of the icosahedral ${\mathrm{B}}_{12}$${\mathrm{O}}_{2}$ crystal are studied by means of first-principles calculations. The results are compared with the other ${\mathrm{B}}_{12}$-based compounds with the same rhombohedral crystal structure. ${\mathrm{B}}_{12}$${\mat…
The standard theoretical model of two-level systems in low-temperature glasses is modified so that the temperature dependence of the effective homogeneous optical linewidth is in agreement with experiment. This alters the time dependence of the width due to spectral diffusion. The new results fit recent experiments wi…
We studied the confinement effects on the phonon spectra of CdTe quantum dots by means of resonant Raman scattering measurements. The spectra show clearly longitudinal optical phonons, surface phonons and some of their overtone combinations. We show that the scattering due to surface phonons increases as the quantum d…
Measurements of the temperature dependent transport properties of epitaxial BaTiO3 are reported. Electrical resistivity and thermoelectric power were measured over the temperature range of 77–300 K. Room temperature resistivities of the as-deposited, undoped films range from 105 to 108 Ω cm, while values as low as 55…
We report the properties of an all-solid-state electrochromic (EC) device that can be switched over a useful range of optical transmissions with voltages below 1 V. This switching voltage is smaller than required by other solid-state EC devices reported to date. We attribute the lower-than-normal switching voltage to…
The hexagonal ZnS nanocrystals were synthesized in polymer matrix. The ZnS polymer composite doped with tetraphenylbenzidine (TPB) as light-emitting layer was used to fabricate a single layer structure light-emitting diode which has a low turn on voltage such as 2.5 V. The electroluminescence spectrum was obtained at…
Oriented thin-film tin-doped indium oxide (ITO) was heteroepitaxially grown on optically polished (100) or (111) planes of single-crystalline yttria-stabilized zirconia (YSZ) substrates using e-beam evaporation or dc magnetron sputtering techniques. Pole figure x-ray diffraction analyses revealed that the heteroepitax…
The intra-4f transition close to 1.54 \ensuremath{\mu}m of Er implanted into Si shows rich fine structure due to the crystal field of different defect types. Making use of the influence of implantation and annealing parameters, additional doping, temperature, and excitation power, we identify groups of lines belonging…
The response of aluminum oxide-filled poly(dimethyl siloxane) and poly(diphenylsiloxane-co-dimethylsiloxane) elastomers, containing 3–24 mol % diphenylsiloxane, to cyclic stress at elevated temperatures (dynamic creep) was evaluated. The materials could be divided into two classes, based on their response to the appli…
The excitons in near-surface ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}/\mathrm{GaAs}$ QW's have been investigated by photoluminescence excitation and magnetophotoluminescence spectroscopy. The dielectric enhancement of excitons is demonstrated by measuring the splitting of the $2s$ and $1s$ exciton…
We have used photoemission and electron-energy-loss spectroscopies to determine the surface and bulk electronic structure of a single-crystal sample of the alkali-metal oxide ${\mathrm{Li}}_{2}$O. The predominately O 2p valence band exhibits two main features in the photoemission spectrum, whose relative widths are co…
A Raman study of La-doped lead zirconate titanate ceramics with La/Zr/Ti ratios of 9/65/35 and 12/40/60 has been undertaken in order to compare the onset of ferroelectric order in these two compositions. Some features, such as a splitting of a threefold degenerate T1u mode of the cubic structure into at least two line…
This redetermination of the structure of l-cysteine, C3H7NO2S, forms part IV in the series of crystal structures of hydrophobic amino acids. The thiol groups of the two molecules in the asymmetric unit are involved in S-H⋯O and S-H⋯S interactions. The associated C-S bond lengths are significantly different. The absolu…
The energetical advantage of diamond in comparison with graphite caused by small particle sizes is established by modeling and computation of free energy. The results, obtained for low external pressure, P\ensuremath{\simeq}0, and for temperatures up to 1100 \ifmmode^\circ\else\textdegree\fi{}C, indicate that diamond…
Highly random copolymers of ϵ-caprolactone (CL) and D,L-lactide (LA) were synthesized by a new catalyst system, rare earth chloride–propylene oxide (PO) system. In the presence of propylene oxide, all rare earth chlorides tested are highly effective for the copolymerization. The influences of reaction conditions on th…
Monte Carlo computer simulations were carried out on filled networks of poly(dimethylsiloxane) (PDMS), which were modeled as composites of crosslinked chains and randomly arranged spherical filler particles. The primary concern of the investigation was the effect of the excluded volume of these particles on the elasto…