Materials Literature
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The kinetics of oxygen removal from CeO2 were investigated using thermogravimetric analysis, at high temperatures, under a reducing atmosphere of Ar–6%H2. A chemical diffusivity model was developed that takes into account the composition dependence of both the pre-exponential factor and the activation energy. In this…
Raman and infrared reflection spectroscopies provide us information on electronic properties in polar semiconductors. In the present work, we have employed a dielectric function including the LO phonon damping in addition to the TO phonon damping and free carrier damping, and analyzed observed spectra of n-type 4H–SiC…
Correlation between the size-enhanced Stokes shift and the size-enlarged band gap expansion of porous silicon has been derived, which allows us to discriminate the effect of electron-phonon coupling from the effect of crystal binding on the blueshift in photoemission and photoabsorption of nanosolid silicon. Matching…
Thermoelectric properties of layered oxyselenides La1−xSrxCuOSe (x=0.00 to 0.20) were investigated to evaluate the potential as thermoelectric material. Temperature dependence of the electrical conductivity and Seebeck coefficient measured in a temperature range of 373 to 673 K indicated that nondoped LaCuOSe was a p-…
Microstructure and origin of the orange photoluminescence (PL) band of visible luminescing spark-processed germanium (sp-Ge) has been studied using simultaneous micro-Raman and -PL spectroscopy and scanning electron microscope. Instability of the sp-Ge film to energetic electron beams (⩾5 keV) during SEM measurements…
High pressure Raman scattering and x-ray diffraction studies of the molybdate ${\mathrm{Sc}}_{2}({\mathrm{MoO}}_{4}{)}_{3}$ are presented. A sequence of changing symmetry effects is observed through two structural phase transitions ending up with an amorphous state. The observed two structural phase transformations ar…
A CaF2:Er3+ single crystal was grown by the Tammann–Stober method. The potential of this material as a laser crystal for 1530 nm emission was established by quantitative analysis of the optical absorption and emission spectra. Assuming the tetragonal symmetry of the Er3+ sites, the Bkq crystal field parameters, Racah…
${\mathrm{CoS}}_{2}$ has recently been predicted to be highly spin-polarized, but very little is known about its magnetotransport properties. We find that this system exhibits a large anomaly in the resistivity at the Curie temperature ${(T}_{C}),$ which shows a pronounced shift with applied field, resulting in negati…
Inorganic multilayer films and hollow shells with pillared architectures have been fabricated layer-by-layer on spherical poly(methyl methacrylate) (PMMA) templates as well as flat substrates through the electrostatic self-assembly technique. Positively charged polyoxocations of aluminum Keggin ions were employed both…
Dielectric loss spectra at both ambient and elevated pressure are presented for propylene glycol (PG), dipropylene glycol, and tripropylene glycol. While in previous literature the excess wing (EW) was observed only for PG, we show herein that under high pressure an EW (coexistent with a secondary \ensuremath{\beta} r…
The present article deals with the optimized processing conditions leading to the highest density of Si nanoclusters which play the role of sensitizing centers for the nearby Er ions within a silica matrix. The layers were obtained by reactive magnetron sputtering under a plasma of Ar mixed to different rates of hydro…
The structure and folding of dihydrofolate reductase (DHFR) from Escherichia coli and the mutant G121V-DHFR, in which glycine 121 in the exterior FG loop was replaced with valine, were studied by molecular dynamics simulations and CD and fluorescence spectroscopy. The importance of residue 121 for the chemical step du…
We have investigated the electronic structure of Zn1−xMxO (M: 3d transition metal) by x-ray absorption spectroscopy. Using configuration–interaction cluster-model analyses, electronic structure parameters have been deduced and their chemical trend is discussed. Results show that the p–d exchange constant Nβ is negativ…
Defect-mediated diffusion and viscous flow of network forming liquids have been investigated. An analytical formula of viscosity has been derived with two-exponential forms demonstrating high activation energy at low temperatures and low activation energy at high temperatures with Arrhenius-type behavior for both high…
We demonstrate the possibility of a selective nonequilibrium cap opening of carbon nanotubes as a response to femtosecond laser excitation. By performing molecular dynamics simulations based on a microscopic electronic model we show that the laser-induced ultrafast structural changes differ dramatically from the therm…
The adsorption of several aromatic compounds over microcrystalline cellulose was studied by molecular modeling and experimentally using gas chromatography. Experimental adsorption enthalpies were obtained from an equation based on Clausius-Clapeyron formalism and the temperature dependence of retention volume at infin…
Incoherent quasi-elastic neutron scattering (IQENS) and Fourier-transform infrared (FT-IR) absorption measurements have been employed to investigate the diffusional and vibrational dynamics on water confined in a NaA zeolitic matrix. In analogy with the results of a recent quasi-elastic neutron scattering experiment o…
Formation of singlet oxygen in solution by using Si nanocrystals as photosensitizers has been demonstrated. It has been shown that the absorption band of 1,3-diphenylisobenzofuran (DPBF) in benzene centered at 416 nm decreases by irradiating green (514.5 nm) or red (632.8 nm) light if fresh porous Si powder is dispers…
We report measurements of the optical dispersion in ferroelectric Langmuir–Blodgett films of polyvinylidene fluoride (70%)-trifluoroethylene (30%) copolymer, using variable-angle spectroscopic ellipsometry over a wide spectral range from infrared to ultraviolet. Film thickness averaged 1.78±0.07 nm per deposition laye…
Time-resolved photoluminescence measurements on size-selected silicon nanocrystals have been carried out in order to elucidate the nonexponential behavior of the photoluminescence decay kinetics. The nanoparticles are gas-phase synthesized, extracted as a supersonic beam, size selected, and deposited downstream as fil…