Materials Literature
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The electron spin resonance of the Gd3+ ion has been studied in two series of glasses having the molar compositions 6SiO2:5Na2O: x (Gd2O3 + Y2O3) with 0 ≤ x ≤ 0.5 and 500SiO2: x Na2O:1Gd2O3 with 2.5 ≤ x ≤ 494. The spectra were nearly independent of temperature and sample composition, but varied strongly with microwave…
The evolution with $x$ of the monoclinic-to-tetragonal transition temperature and of the room-temperature monoclinic structures of the system ${\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{O}}_{2}$ have been reexamined and extended to cover the entire solid-solution range $0\ensuremath{\le}x<0.20$. The s…
We report the preparation of intercalation compounds of 2H–TaS2 with post transition period elements. In general we find that elements to the left of the metalloid line in the periodic table will intercalate TaS2. Crystallographic lattice parameters, the maximum amount intercalated per Ta, magnetic susceptibility, and…
A phenomenological dielectric approximation is proposed for studying the response of metal surfaces to external charge distributions and is illustrated by detailed calculations using the Thomas-Fermi model. The procedure is based on the replacement of the dielectric-response kernel in a constitutive relation by its as…
By using the techniques of wavelength-modulation spectroscopy, we have measured the reflectivity $R(\ensuremath{\omega})$ and the derivative of the reflectivity, $\frac{(\frac{1}{R})dR}{d\ensuremath{\omega}}$, for PbTe, PbSe, and PbS from 1.5 to 6 eV. We have independently calculated the band structure, frequency-depe…
We discuss the threshold conditions for the nucleation of a static Helfrich distortion of a planar cholesteric structure under a magnetic field or an ac electric field applied parallel to the helical axis. In opposition to the case of nematics, the magnetic threshold in cholesterics is definitely lower than the thresh…
We observe a second-order nematic to smectic-$A$ phase transition in $p$-nitrilebenzylidene-$p$-octyloxyaniline using the Rayleigh scattering technique. The twist elastic constant ${K}_{22}$ diverges at the transition, with the critical exponent $\ensuremath{\nu}=0.66\ifmmode\pm\else\textpm\fi{}0.05$ in agreement with…
The viscosity of liquid anorthite has been determined over the temperature ranges between 1450°–1620°C and 820°–950°C. The high-temperature data agree well with previous experimental data and with predictions of the Bottinga and Weill model. The overall log (viscosity) versus 1/T relation exhibits pronounced and rathe…
Tungsten carbide catalyzes the formation of water from hydrogen and oxygen at room temperature, the reduction of tungsten trioxide by hydrogen in the presence of water, and the isomerization of 2,2-dimethylpropane to 2-methylbutane. This catalytic behavior, which is typical of platinum, is not exhibited at all by tung…
The splay and bend elastic constants of nematic $p$-cyanobenzylidene-${p}^{\ensuremath{'}}$-octyloxyaniline have been measured as a function of temperature. The bend constant diverges near the nematic-smectic-$A$ phase change, with the temperature dependence predicted by de Gennes. The splay constant shows no anomaly,…
A brief review is first made of systems for which the spin-1/2 Ising model in a transverse field provides a useful description (insulating magnetic systems, order-disorder ferroelectrics, cooperative Jahn-Teller systems and other systems with 'pseudo-spin'- phonon interactions). A perturbation expansion is then develo…
One of the problems associated with building any aberration-corrected electron microscope objective lens lies in the difficulty of obtaining a sufficiently short focal length. A number of systems have focal lengths in the 1cm. range, and these are more suitable for microprobe work. If the focal length can be made shor…
The image collecting system of the experimental high resolution electron microscope being developed in this laboratory must be compatible with the ultra-high vacuum (10 −10 Torr) maintained in the total column. The characteristics of an SEC porous KCl target used to record directly the primary high energy beam has bee…
Changes in dimensions which occur when fabric is released from loom are predicted. Analysis was not extended to finished fabrics, which is difficult. It is possible to predict the gray fabric dimensions of elastomeric fabrics, using relatively simple analytic methods.
The phase diagram for the system K 2 SO 4 ‐Cs 2 SO 4 was determined by using DTA for melting relations and DTA and high‐temperature X‐ray diffractometry for subsolidus relations. At the solidus the system shows complete solid solubility, with a minimum at 940°C and 50 mol% Cs 2 SO 4 . Orthorhombic K 2 SO 4 and Cs 2 SO…
An earlier postulate, that physically trapped electrons (e t − ) are responsible for a narrow e.s.r. singlet at g = 2.0028 formed by exposure of glassy propylene carbonate to 60 Co γ-rays at 77°K, is re-examined. An alternative, that propylene carbonate radical anions are formed, in which the extra electron is largely…
The thermal conductivity of CdSxSe1−x (0≤x≤1) solid solutions was measured between 100 and 300 °K. Analysis of the experimental data shows that normal processes played an important role in phonon scattering, and that mass and strain fluctuations equally contribute to thermal resistivity in the temperature range studie…
An investigation of the effects of 10.6-μm laser radiation on triglycine-sulfate (TGS) crystals determined that the primary irreversible damage mechanisms in TGS pyroelectric detectors are cracking and thermal decomposition (charring). Irradiation thresholds for cracking and charring were determined for TGS crystals o…
ADVERTISEMENT RETURN TO ISSUEArticleNEXTRate of electron transfer between tris(3,4,7,8-tetramethyl-1,10-phenanthroline)iron(II) and -(III) ions from nuclear magnetic resonance studiesMan-Sheung Chan, J. Barry DeRoos, and Arthur C. WahlCite this: J. Phys. Chem. 1973, 77, 18, 2163–2165Publication Date (Print):August 1,…
From thermoluminescence (TL), thermally stimulated currect (TSC), and photoluminescence and photoconductivity kinetic response measurements, the excitation mechanism of the Cr3+ luminescence center in SrTiO3 is explored. Based primarily on the strong correlation between TSC and TL, it is concluded that the dominant ex…