Materials Literature
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The concept of mean-field rigidity percolation at average coordination number 〈r〉=2.4 in covalently bonded inorganic glasses is shown to be relevant to the liquid-state behavior of glass-forming chalcogenide systems. In particular it correlates with remarkable variations in ``fragility'' and excess heat capacity which…
Abstract Some organic crystalline solids that comprise highly polar molecules and that form non-centrosymmetric crystal structures exhibit second-order nonlinear optical properties and laser-damage thresholds that are potentially superior to those of currently available inorganic systems. This realization has led to a…
Ultrasound causes high-energy chemistry. It does so through the process of acoustic cavitation: the formation, growth and implosive collapse of bubbles in a liquid. During cavitational collapse, intense heating of the bubbles occurs. These localized hot spots have temperatures of roughly 5000 degrees C, pressures of a…
This book deals with the methods of X-ray production at a level which is accessible to advanced undergraduates and researchers who use X-rays. It also discusses the fundamentals of these physical properties from an experimental viewpoint which is not covered in more specialised texts. The book begins with a survey of…
Abstract A mathematical model for simulation of industrial process of solid state polycondensation of poly(ethylene terephthalate) (PET) has been developed. The model eliminates errors evident in the earlier models by proper formulation. The model results have been validated by experimental data in the literature. It…
The author presents a formalism for the study of the effects of alloy disorder at crystalline interfaces on the phonon boundary scattering cross section. The disordered region is treated within the coherent potential approximation adapted to the interface geometry. The formalism is based on t-matrix scattering theory…
We have investigated the epitaxial growth of Zn1−x CdxSe epilayers and ZnSe/Zn1−x CdxSe superlattices (0≤x≤1) on (100)GaAs. Although thick epilayers of Zn1−x CdxSe are prone to defect formation with increasing Cd content, the structural and optical characteristics improve remarkably when Zn1−x CdxSe is in the form of…
The critical single domain size for a uniaxial magnetic material under variable external conditions (temperature and magnetic field) is discussed.
It is proposed that the structure of a new layer AB, which forms between the components A and B, is defined by parameters of two-stage interfacial reactions. The two stages, namely transition of A atoms through the AB/B boundary and rearrangement of atoms in B into AB, have independent rates. In the initial stage of t…
The crystal structures of NH 4 SCN are determined in the tetragonal phase I (122°C) and the orthorhombic phase II (100°C, 110°C and 115°C) from X-ray diffraction data. In phase I, SCN - ion is in disordered state taking two equivalent configurations. In phase II, the ordering of SCN - ion correlates to the spontaneous…
Cristallisation dans P2 1 /c avec a=5,767, b=10,574, c=6,835 A, β=105,04 o , z=4; affinement jusqu'a R0,062. L'arrangement atomique est identique a celui de NaBUO 5 orthorhombique, sauf en ce qui concerne l'ion alcalin. Les ions lithium sont, en effet, situes dans les sites tetraedriques, tandis que les ions sodium se…
Cristallisation dans Pbcn avec a=5,683, b=4,784, c=14,648 A, z=4; affinement jusqu'a R=0,063. Cette structure, differente de celle du Li 2 Si 2 O 5 stable, est au contraire similaire a celle du Na 2 Si 2 O 5 -α. Elle consiste en feuillets infinis de silicate, composes de tetraedres de SiO 4 se partageant les sommets,…
The 19F n.m.r. spectrum of 3-fluoro-3-deoxy-D-glucose (3FG) in a red-cell suspension was observed to contain separate resonances from the intra- and extra-cellular populations of both the alpha- and beta-anomers. This phenomenon was used with an n.m.r. spin-transfer procedure to measure the rate of exchange of the ano…
The revised Enskog kinetic theory (RET) is used to describe transport in a hard sphere crystal. The connection between the RET and the exact density functional theory (DFT) description of the solid state is established. The RET is used to derive the dissipative linear equations of elasticity. The elastic moduli in the…
Time-resolved light scattering was employed to elucidate the dynamics of phase separation in mixtures of polycarbonate (PC) and polymethyl methacrylate (PMMA). Blends of PC and PMMA of moderately low molecular weight reveal the coexistence of an upper critical solution temperature (UCST) and a lower critical solution…
The band structure and the interband optical conductivity of a ${\mathrm{LiB}}_{3}$${\mathrm{O}}_{5}$ crystal with excellent nonlinear optical properties are studied by means of a first-principles method. The electronic structure is characterized by highly localized bands with a direct gap of 7.37 eV at \ensuremath{\G…
Rate constants for OH(X 2Πi, v=1–3) vibrational relaxation induced by nonreactive collision with O2 have been measured. OH(v) is created by the H+O3 →OH(v≤9)+O2 reaction in an electron-irradiated O3, H2, Ar mixture. OH(v) fundamental and first overtone IR emission is observed using time-resolved Fourier spectroscopy.…
Calcium aluminate glasses melted in graphite crucibles were found to show photochromism. Upon exposure to ultraviolet radiation, broad absorptions with an apparent peak of around 2 eV and a shoulder around 3.5 eV were induced, and after interruption of the light illumination both bands faded at room temperature. A dis…
We report measurements on the electrical- and thermal-transport properties of fluorine-intercalated vapor-grown carbon fibers ${\mathrm{C}}_{\mathit{x}}$F with the carbon-to-fluorine-atom ratio x between 4.1 and 5.8. The electrical resistivity is found to be very sensitive to the fluorine concentration. Indeed, while…
A general theoretical approach to the modeling of several different process steps in fabrication of ion-exchanged channel waveguides is presented. All of the commonly used fabrication processes are included, and the nature of the ion source and the effect of external electric voltage are taken into account. The model…