Materials Literature
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The theory of phase stability in the Ni-Au alloy system is a popular topic due to the large size mismatch between Ni and Au, which makes the effects of atomic relaxation critical, and also the fact that Ni-Au exhibits a phase separation tendency at low temperatures, but measurements at high-temperature show an orderin…
Ce activated SrGa2S4 blue emitting phosphors were examined using electron paramagnetic resonance and x-ray diffraction to determine the local environment and oxidation state of the Ce ion. Photothermal deflection and photoluminescence spectroscopies were applied to determine absorption and emission characteristics. It…
We have investigated the high-temperature superionic transition of the anion-excess fluorite with x = 0.06 using both monochromatic and time-of-flight Laue single-crystal neutron diffraction. The measured Bragg intensities indicate that the cuboctahedral defect clusters found at ambient temperature start to break up i…
Million atom molecular-dynamics simulations are performed to investigate the structure, dynamics, and mechanical behavior of cluster-assembled ${\mathrm{Si}}_{3}{\mathrm{N}}_{4}$. These solids contain highly disordered interfacial regions with 50% undercoordinated atoms. Systems sintered at low pressures have percolat…
The order - disorder phase transition in the linear chain compound (TMMC) was investigated by means of x-ray diffraction. The hexagonal structure at room temperature (space group with Z = 2) is characterized by an orientational disorder of the organic group TMA. A weakly first-order phase transition occurs at 126 K wh…
The Raman spectrum of icosahedral \ensuremath{\alpha}-boron presents a very sharp peak at $525{\mathrm{cm}}^{\ensuremath{-}1}$ that was consistently rejected from the lattice modes but is still unexplained. New Raman scattering experiments under pressure are compared with ab initio lattice dynamics calculations. The v…
Picosecond dynamics of exciton emission and absorption have been studied in neat thin films of a variety of poly (phenylene vinylene) derivatives. We found that the stimulated emission band of 120 nm width and $\ensuremath{\sim}1\mathrm{ns}$ duration, which is observed at low exciton density $n$, collapses at $n>{1…
For both molecules and periodic solids, the ionic dynamical charge tensors which govern the infrared activity are known to obey a dynamical neutrality condition. This condition enforces their sum to vanish (over the whole finite system, or over the crystal cell, respectively). We extend this sum rule to the non trivia…
A generalization of the local density approximation (LDA) method for systems with strong Coulomb correlations is described which gives a correct description of the Mott insulators. The LDA+U method takes into account orbital dependence of the Coulomb and exchange interactions which is absent in the LDA. The scheme can…
The dynamic viscoelastic properties for binary blends consisting of an isotactic polypropylene (i-PP) and an ethylene-1-hexene copolymer (EHR) were investigated in both solid and molten states to reveal the relation between miscibility in the molten state and the morphology in the solid state. In this study, two types…
Using the Einstein relation for a grain boundary, the creep controlled by grain boundary diffusion is compared with that controlled by grain boundary viscous flow. It is found that the creep rate controlled by viscous flow has the same order as does that controlled by grain boundary diffusion. This suggests that the c…
This chapter provides an overview of major membrane concepts and materials. It discusses besides membranes made from a mixed ionic–electronic conducting, other membranes incorporating an oxygen ion conductor and presents data from oxygen permeability measurements on selected membrane materials. The rate at which oxyge…
Experiments on the analysis of the wear debris produced during the polishing of diamond and the rapid sliding of diamond upon diamond using a high-speed sliding machine are presented. The debris was studied by electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) and by transmi…
BACKGROUND: Because prior studies have established the critical role of the endothelium in preventing vascular thrombosis and intimal thickening, we designed a series of experiments to determine the feasibility of percutaneous local catheter delivery of recombinant protein to accelerate development of an intact endoth…
The temperature- and frequency-dependent dielectric susceptibility parallel to the ferroelectric axis of crystals was studied in the ferroelectric phase. The dispersion corresponding to a critical slowing down of the thermal dipole relaxation was observed in the vicinity of in the frequency range 1 - 10 MHz. Besides,…
On structural phase transitions in n-butylammonium chloroantimonate(III) and chlorobismuthate(III) crystals: x-ray, differential scanning calorimetry, dilatometric and dielectric dispersion studies, P Ciapala, R Jakubas, G Bator, J Zaleski, A Pietraszko, M Drozd, J Baran
Buried interfaces of thin Al/Ta2O5 and Ta2O5/Al films were studied using the x-ray photoelectron spectroscopy technique. The peak decomposition technique was employed to identify the composition and chemical states at the interface region. It was observed that there is an “intermixing layer” at the Al/Ta2O5 interface,…
Photoluminescence decay curves and nanosecond time-gated spectra were measured from silicon implanted SiO2 layers after thermal annealing. Different ion fluences and annealing times were tested. Three components emitting blue-green light with lifetimes of about 0.4, 2, and 10 ns were detected. The peak position of all…
Spin correlations in metallic and insulating phases of ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ and its derivatives are investigated using magnetic neutron scattering. Metallic samples have incommensurate spin correlations varying little with hole doping. Paramagnetic insulating samples have spin correlations only among nea…
Europium impurities can be incorporated in two forms: divalent and trivalent. Phosphors activated by or find important applications. Exposure to ionizing radiations is known to cause conversion. This conversion is important in understanding thermoluminescence and radiophotoluminescence applications. However, there hav…