Materials Literature
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Abstract The increase in the viscosity of an aqueous solution or gel of hydroxypropylmethylcellulose (HPMC) in the presence of an anionic surfactant is attributed to a two‐step process: (a) the surfactant undergoes ion–dipole interaction with the ethereal oxygen in HPMC, in the absence or presence of water, and (b) hy…
We have measured the surface index change and birefringence in K(+)-Na(+) ion-exchanged waveguides and compared the results with theory. The contribution to the index change caused by the polarizability/volume changes (Deltan(p)) is calculated using two theoretical models which use empirical relations based on the gla…
Abstract Composites of styrene–butadiene rubber were prepared with three different types of lead oxide, namely, monolead oxide (PbO), lead dioxide (PbO 2 ), and red lead oxide (Pb 3 O 4 ). Concentrations of Pb 3 O 4 ranging between 17 and 88 wt % were utilized, whereas 87 wt % was used for PbO and PbO 2 . The prepared…
Molecular dynamics computer simulations have been carried out on a system consisting of cylindrically symmetric molecules with length-to-breadth ratio k = 3 and well depth ratio k′ = 5 interacting through the Gay-Berne potential. For this system we have located the coexistence points corresponding to the isotropic-nem…
Abstract Tests in Berea sandstone cores have been carried out which simulate scale inhibitor treatments by the precipitation squeeze method. The studies have shown that squeezes with common phosphonate inhibitors last twice as long as squeezes using common polymer inhibitors in cores containing brines with low calcium…
Indium—tin oxide (ITO) applied to optoelectronic devices must meet several requirements simultaneously, i.e. electrical conductivity, optical transparency, and structurability by photolithography. As will be shown, these properties are mainly based on the microstructure of the ITO films. The microstructure changes fro…
The superspace description of incommensurably modulated crystals is used to generalize commonly used band-structure methods to cover this class of crystals. The methods considered are the nearly-free-electron method, the tight-binding method, and the Korringa-Kohn-Rostoker equations in the atomic-sphere approximation.…
We present a calculation of the cluster integrals which appear in the density expansion of the inverse mean cluster size for an assembly of spherical particles with a square well potential where the range of connectedness is equivalent to the interparticle interaction range. This percolation series is constructed to t…
The effects of uniaxial stress σ y y on the incommensurate (INC) phase transition of quartz have been investigated by light scattering spectroscopy. The 1q INC phase is induced between β and the 3q INC phase and its region becomes wider with the increase of stress. Anomalies of the central peak in the Rayleigh-Brillou…
A method to determine the switching field distribution Hs(■cr>gc0) of powder assemblies of magnetically hard materials with a random orientation of the easy axes is described. The method is based on the ferromagnetic resonance absorption and the measurements of remanence curves. Direct information about the swi…
The temperature dependence from ambient to 2325 K of the high frequency E2g mode intrinsic to the hexagonal phase of boron nitride has been determined using a pulsed-excitation gated-detection technique which effectively discriminates against sample blackbody emission. A monotonic decrease of 80 cm−1 in mode frequency…
The resistivity of polypyrrole films, from 300 to 1.3 K, doped with ${\mathrm{ClO}}_{4}$ ions at various concentrations to have a different number of polarons and bipolarons, can be better fitted by ${\mathit{T}}^{\mathrm{\ensuremath{-}}1/3}$ than ${\mathit{T}}^{\mathrm{\ensuremath{-}}1/4}$. The conduction process in…
Chlorine incorporated into silica glasses by sintering porous soot rods under Cl2/He atmosphere or by fabricating with plasma methods were found to be mostly as ≡SiCl, which gives rise to an optical absorption tail above ≂7.5 eV. The cross section of the optical absorption at ≂7.77 eV (160 nm) was found to be 1.14×102…
Fluorescence spectra have been measured in Ca(PO 3 ) 2 :Eu 3+ at 77 K under dye laser excitation at various energies within the absorption lines due to the transitions 7 F 0 , 7 F 1 - 5 D 0 , 5 D 1 . It has been found that the 5 D 0 - 7 F 0 transition probability and the mean energy of the three 5 D 0 - 7 F 1 lines ar…
A free-energy model (FEM) for bonding in amorphous covalent alloys is developed and applied to the ternary a-${\mathrm{Si}}_{\mathit{x}}$${\mathrm{N}}_{\mathit{y}}$${\mathrm{H}}_{\mathit{z}}$ alloy system. The Gibbs free energy of mixing ${\mathit{G}}_{\mathit{M}}$=${\mathit{H}}_{\mathit{M}}$-${\mathit{TS}}_{\mathit{M…
A b initio electronic structure calculations on several low-lying valence states of B3 have been carried out using correlation-consistent polarized valence double-zeta basis sets and complete-active-space self-consistent field treatments of electron correlation. Stable triangular structures, linear structures, and Jah…
The optical properties of diamond are examined in the energy region up to 25 eV. A modified parabolic-band model is used to explain existing experimental data on the dispersion of the real and imaginary part of the dielectric function. Optical properties such as reflectance, index of refraction, and extinction coeffic…
The interstice statistics of the oxygen sublattice of the canonical inorganic glass-former silica have been investigated theoretically for a number of structural models of v-${\mathrm{SiO}}_{2}$. It is found that spheres with radii smaller than 2.41 \AA{} minus the oxygen radius can travel freely through a model of v-…
Thin films were deposited by pulsed uv-laser (ablation) deposition of Y1Ba2Cu3O7−x (YBCO), and composite zirconia and yttria targets onto silicon wafers. These films were analyzed to ascertain the chemical and physical structure of the film interfaces and further the development of Si substrates for superconducting YB…
Multiple-scattering theory is generalized to take into account the effects of spin-orbit interaction and spin polarization of the photoelectron that are at the origin of the magnetic x-ray circular dichroism (MXD) effect observed in x-ray-absorption spectra where the final state of the photoelectron is delocalized. Th…