Materials Literature
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Diamond films were grown on silicon by microwave chemical-vapor deposition using a CH4–H2 gas mixture. The crystalline quality of the films was assessed through their α-particle detection performance, a property highly sensitive to film quality, by using a 5.5 MeV Am241 source. A maximum collection efficiency η of 70%…
An explanation, using the logarithmic derivative method, is given for some previously unexplained features of the temperature dependence of the conductivity for barely insulating Si:As for $10\mathrm{K}<T<78\mathrm{K}.$ The results and analysis suggest an important high-temperature correction to the prefactor of…
We have used an isothermal microcalorimetric method to study photoinduced effects in porous silicon (PS). In the photo-oxidation investigations using constant wavelength, sharp threshold behavior with threshold energies 3.9 eV for n-PS and 4.7 eV for p+-PS were observed. The two discussed origins for the different thr…
Two types of polymer–silica nanocomposites have been prepared by undergoing free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) either in the presence of HEMA-functionalized SiO2 nanoparticles (Type 1) or during the simultaneous in situ growing of the silica phase through the acid-catalyzed sol–gel polym…
Monte Carlo simulations show that the inherent tendency for decomposition of the Si-Ge solid mixture is totally suppressed in the amorphous phase. Yet, the distribution of Si and Ge atoms in the network is not random as in the crystal, but there is a strong tendency of homopolar bonds to cluster locally, even at high…
The atomic order has a strong influence on the martensitic transformation behavior in Cu-based shape memory alloys. In this work we have studied the influence of the quenching and postquench aging treatments on the atomic order of the metastable β phase obtained by quenching in Cu–Al–Ni shape memory alloys by means of…
X-ray absorption near edge structure (XANES) spectra of crystalline (c)- and amorphous (a)-Si–C–N thin films were measured at the C, N, and Si K edge using the fluorescence and sample drain current modes. A sharp peak similar to the C 1s core exciton in chemical vapor deposition diamond is observed, which can be assig…
Magnetic field induced transitions in antiferromagnetic ${\mathrm{La}}_{1.4}{\mathrm{Sr}}_{1.6}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ were studied using magnetization measurements and a high-resolution magneto-optical imaging technique. We report the direct observation of the formation of ferromagnetic domains appearing a…
The growth, structural and cathodoluminescent (CL) properties of 4 wt. % europium-doped yttrium oxide $({\mathrm{E}\mathrm{u}:\mathrm{Y}}_{2}{\mathrm{O}}_{3})$ thin films are reported. The ${\mathrm{E}\mathrm{u}:\mathrm{Y}}_{2}{\mathrm{O}}_{3}$ films were grown in situ using a pulsed laser deposition technique. Our re…
Using a two-dimensional Ginzburg–Landau model and the finite-element computational method, we have calculated stable domain configurations resulting from a second-order ferroelectric phase transition for a finite-sized system. The boundary conditions applied here correspond to fully charge compensated situations, eith…
The resonance Raman spectrum of Ag7, mass selected out of a cation beam of sputtered silver, neutralized, and codeposited with solid Ar, is presented. By comparing the observed spectrum with one calculated using density functional theory one concludes the structure of the silver septamer to be a tricapped tetrahedron.…
The protective effect of trehalose on biological membranes against freezing or dehydration has been the subject of many studies aimed to understand the reasons why some lower organisms, under stress conditions, synthesize trehalose. In this work we report the results of a study on Poly(Ethylene Oxide)/trehalose/water…
A model, consisting of triangular trimers on the triangular lattice is presented. In analogy to the dimer problem, these particles cover the lattice completely without overlap. The model has a honeycomb structure of hexagonal cells separated by rigid domain walls. The transfer matrix can be diagonalized by a Bethe Ans…
Poly(triacetylenes) are rodlike molecules with electrons delocalized over a one-dimensional path. We show that they exhibit a power-law dependence of the second-order hyperpolarizability gamma on the monomer unit n for short molecules and a smooth saturation toward a linear increase in longer molecules. The power law…
We report on temperature-dependent sound velocity measurements of surface acoustic waves performed on small ${\mathrm{VO}}_{2}$ single crystals by means of ultrasonic microscopy. The elastic behavior of this compound has been studied ultrasonically through its metal-insulator transition. The investigations reveal a st…
The erosion of carbon by intensive hydrogen bombardment has been recently shown to decrease sharply at very high fluxes $(\ensuremath{\sim}{10}^{19}\mathrm{ions}/{\mathrm{cm}}^{2}\mathrm{s}).$ This effect cannot be explained by standard sputtering or erosion models, yet understanding it is central for selection of fus…
Genes involved in allose utilization of Escherichia coli K-12 are organized in at least two operons, alsRBACE and alsI, located next to each other on the chromosome but divergently transcribed. Mutants defective in alsI (allose 6-phosphate isomerase gene) and alsE (allulose 6-phosphate epimerase gene) were Als(-). Tra…
Color-center formation in F-doped, OH-free synthetic SiO(2) glasses by irradiation with F(2) excimer lasers (157 nm) was examined as a function of the F content. The concentration of photoinduced E(') centers was reduced to approximately 1/20 by 1 mol.% F(2) doping and remained almost constant on further doping to 7.3…
A theoretical investigation of the recently observed enhanced thermoelectric power S in (111)-oriented n-type $\mathrm{PbTe}/{\mathrm{Pb}}_{1\ensuremath{-}x}{\mathrm{Eu}}_{x}\mathrm{Te}$ multiple-quantum-wells $(x\ensuremath{\simeq}0.09)$ has been carried out, including both longitudinal acoustic phonon deformation po…
Deformation behavior of the segmented block copolymers was studied with synchrotron small-angle X-ray scattering (SAXS) and Fourier transform infrared spectroscopy (FTIR) methods. Polyurethanes used in this work consist of 4,4′-methylene-bis(phenyl isocyanate) and butanediol as a hard segment, and poly(tetramethylene…