Materials Literature
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Presents a microscopic theory to calculate the incoherent scattering functions S s (qw) in simple classical liquids. The halfwidth at half maximum omega 1 2/(q), of this function is calculated for liquid argon and rubidium, and the results are compared with corresponding MD results. The observed oscillatory behaviour…
The first complete set of electronic structure calculations are reported for elemental boron in its alpha -rhombohedral (12 atoms per unit cell), beta -rhombohedral (105 atoms) and suggested alpha -tetragonal (50 atoms) crystalline forms. The results show that a band picture provides an accurate description of the bon…
Abstract Temperature dependent characteristics of blends of suspension poly(vinyl chloride) with low and high molecular weight plasticizers in the region of processing temperatures have been investigated. The interaction process has been studied under dynamic conditions using the differential thermal analysis (DTA) me…
Abstract Untersucht wurden die katalytischen Eigenschaften von Metall‐Polyphthalocyaninen mit Fe(II), Co(II), Cu(II), Ni(II) und Mg(II) bei der Zersetzung von Wasserstoffperoxid und ihre elektrochmischen Eigenschaften bei der Reduktion von Sauerstoff. Es ergab sich, daß eine große übereinstimmung zwischen katalytische…
ABSTRACT The utilization of scale inhibitors is the most common and promising method of combatting the scale problems in oil and gas field operations. The extension of the scale inhibition technique to geothermal operations faces some problems mainly due to the high temperature and high salinity of the brines. In addi…
ABSTRACT A new approach for computing calcite scaling tendencies is described. Computed values are obtained by exactly solving the chemical equilibria expressions for calcite precipitation. To date, extremely accurate predictions of calcite scale deposition in oilfield systems have been made based on this computed sca…
Abstract Methyl methacrylate (MMA) was copolymerized with acrylamide, N ‐methylacrylamide, N,N ‐dimethylacrylamide, 1‐vinyl‐2‐pyrrolidone, 4‐vinylpyridine, and 2‐dimethylaminomethyl methacrylate in 1,4‐dioxane solution at 65°C, using AIBN as initiator, to yield copolymers with comonomer contents between about 5 and 50…
The phase diagram of chiral smectic $p$-decyloxybenzilidene-${p}^{\ensuremath{'}}$-amino-2-methylbutyl cinnamate in an external magnetic field parallel to the smectic layers has been determined by dielectric and optical measurements up to 14.5 T. The data indicate the existence of a Lifshitz point between the disorder…
Shear mechanical properties have been measured for free-standing films of the liquid crystal $n$-hexyl 4\ensuremath{'}-$n$-pentyloxybiphenyl-4-carboxylate (65OBC) in its stacked-hexatic $B$ phase. The smectic-$I$ phases of (\ifmmode\pm\else\textpm\fi{})-4-(2\ensuremath{'}-methylbutyl)phenyl 4\ensuremath{'}-$n$-nonylox…
Two iron(III) chloride solutions, prepared in suitable chemical conditions, have been examined by the x-ray diffraction technique. The two solutions are isoelectronic (i.e., they have the same average scattering power per chlorine atom) with the hydrated FeCl3⋅6H2O melt previously examined [J. Chem. Phys. 71, 4255 (19…
The polarized Raman and infrared reflectivity spectra of single crystal LiNaSO4 are reported. Symmetry-based vibrational band assignments are given for both the internal and external optic models. The spectra of 6LiNaSO4 clearly identify higher frequency external modes as originating in lithium ion motion essentially…
The radiative lifetimes and collisional deactivation rate constants of Ar[3p5(2P01/2)5p] and Ar[3p5(2P03/2)5p] levels with argon atoms have been measured by time resolved laser induced fluorescence combined with a pulsed discharge for preparation of populations in the Ar(4s) precursor levels. The radiative lifetimes o…
The time dependence of the specific heat of several amorphous materials, such as $a$-Si${\mathrm{O}}_{2}$, $a$-${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, and $a$-As, has been studied in the temperature range 0.1-1 K. It is found that below 0.3 K in all the materials studied the short-time specific heat at about 10 \ensure…
We have studied the quasiperiodic noise generated in Nb${\mathrm{Se}}_{3}$ above the critical electric field where the charge-density waves (CDW's) are depinned. The Fourier spectrum of the noise can be totally described with three fundamental frequencies and their harmonics. At high electric fields the fundamental fr…
Absorption of photons at low power levels below the band edge reversibly alters the molecular structure of Ge${\mathrm{Se}}_{2}$ glass. These structural changes have been analyzed by continuously monitoring the Raman scattering spectrum as a function of time and laser power level. At sufficiently high power levels irr…
Germanium disulfide exhibits three solid forms: an amorphous form ($a$-Ge${\mathrm{S}}_{2}$), a layer-structure crystalline form (2D-Ge${\mathrm{S}}_{2}$), and a quartzlike crystalline form (3D-Ge${\mathrm{S}}_{2}$). We have carried out a series of experiments to determine the effect of pressure on the optical-absorpt…
We have measured the variation of the differential resistance as a function of the electric field for temperatures below those at which the two charge-density waves (CDW) form in Nb${\mathrm{Se}}_{3}$. The shape of the $\frac{\mathrm{dV}}{\mathrm{dI}}$ variation is very sensitive to temperature, particularly below tha…
We report a theoretical survey of defect energetics in $\ensuremath{\alpha}$-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ and rutile Ti${\mathrm{O}}_{2}$ which we relate to structural and transport properties of these materials. The study of these crystals has required us to modify our computational methods based on the Mott…
The photoelectronic properties of nominally pure SrTi${\mathrm{O}}_{3}$ single crystals were studied in detail. A sharp narrow peak near the fundamental absorption edge was observed in both photoconductivity and photoluminescence excitation spectra, although it was not detected in the absorption spectrum. The temperat…
The total energy for Si with various lattice distortions has been calculated using a first-principles linear-combination-of-atomic-orbitals method. The physical properties derived from these calculations include not only the equilibrium lattice constant, cohesive energy, and bulk modulus, but also the internal strain…