Materials Literature
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Abstract The reflectivity of Se and Te single crystals has been measured at near normal incidence for photon energies between 3 and 30 eV with the electric field vector lying parallel and perpendicular to the c ‐axis of the crystals. The measurements were made using the polarized continuum of the synchrotron radiation…
Selection of image-forming electrons that have passed through a small annular zone of the objective lens drastically reduces the resolution-limiting influence of chromatic aberration. Special objective-lens aperture diaphragms are needed for this new method of obtaining high-quality images. The manufacture of the diap…
The ferromagnetic transition temperatures of $\mathrm{Mn}{\mathrm{As}}_{x}{\mathrm{Sb}}_{1\ensuremath{-}x}$ solid solutions for $0\ensuremath{\le}x\ensuremath{\le}1$ have been measured as a function of pressure up to 4.5 kbar. Previous work has shown that for the solid solutions in the concentration range $0.9\ensurem…
Permeation, diffusion, and solubility of helium in several types of vitreous silica were measured. The activation energy for diffusion increases slightly with increasing hydroxyl concentration; no other significant trends were noted. These results are interpreted in terms of a random‐network structural model.
The effects of NH 4 -oxalate (pH 3), Na–dithionite–citrate–bicarbonate (pH 7.3), and K-pyrophosphate (pH 10) on various size fractions of biotite, chlorite, muscovite, and illite minerals were investigated. The data showed that the release of mineral cations by the three chemical extractants increased with decreasing…
Abstract Acrylic acid has been grafted from aqueous solution onto 70 μ isotactic polypropylene‐film previously peroxidized by irradiating in air with both 400 keV electrons and γ‐radiation from a 60 Co source. Ferrous ion has been used to induce the redox decomposition of the macromolecular peroxy species at temperatu…
Abstract Measurements of dielectric constants and infrared reflection were carried out on KH 2 PO 4 , KD 2 PO 4 , and RbH 2 PO 4 single crystals in the temperature range 300 to 500 °K. Both types of measurements show the existence of two distinct phase transitions T p and T 1 in the above range. The T p transition is…
A practical electro-optic page composer has been constructed from single crystal gadolinium molybdate, Gd2(MoO4)3. The characteristic 'ferroelectric-ferroelastic' effect in Gd2(MoO4)3 is based on the existence of bistable states of the optic plane which can be rotated 90° by the application of an electric field E3 or…
A simulation of the development of rolling texture in f.c.c. polycrystals has been performed, assuming that the deformation mechanism is multiple {111} 〈110〉 slip. The predicted crystallite orientation distribution functions for 40% and 80% reduction are in fair agreement with the experimentally determined texture of…
Abstract Tetraphenylporphiniron(II) was synthesized and isolated in a pure state. The iron(II) porphin was in the state of S=2. The spin state of iron(II) porphin varies with the axial ligand field. Oxygeneous axial ligands such as tetrahydrofuran and dioxane gave an intermediate spin state (S=1), while nitrogeneous l…
It is experimentally demonstrated in a new and direct manner that electroluminescence in thin films of ZnS: Tb3+ is excited by the direct impact of hot electrons on the Tb3+ ions. The scheme consists of monitoring as a function of applied voltage across the structure studied-a ZnS: Tb3+, Ta2O5 sandwich-the ratio of fl…
Thermal transition enthalpy changes (ΔHf) were investigated in intact and soluble collagen from a variety of sources and species utilizing differential scanning calorimetry. Results indicated that the ΔHf determinations were not dependent on sample size, method of preparation, or sample purity. The ΔHf values for inta…
The recently reported permanent poling effects in triglycine sulphate (TGS) containing some α-alanine additive is further investigated by pyroeiectric and dielectric measurements. The probable role of an L-alanine molecule in the lattice of TGS is examined in terms of the atomic motions normally required to reverse th…
The Raman spectra of the soft-phonon behavior in the ferroelectric transition in SbSI is studied by means of a new technique in which the phase transition is induced by hydrostatic pressure. The crystal temperature is maintained constant and the ferroelectric transition is created by a linear shift of the Curie temper…
The crystal structure of Bi3TiNbO9, a two-layer member of the Bi4Ti3O12 family, has been refined from x-ray and neutron diffraction data. Bismuth titanium niobate is orthorhombic, space group A21am, with a = 5.431, b = 5,389, c = 25.050 Å, and Z = 4. Distortions from the prototype structure include sizeable shifts alo…
Abstract The flame retardation mechanisms for cellulose treated with systems based on aromatic phosphates and phosphoramides have been investigated through pyrolysis studies on cellulose and related model compounds. Pyrolysis of cellulose treated with phosphates or phosphoramides proceeds through formation of cellulos…
Y2O3 : Yb : Er and Gd2O3 : Yb : Er are efficient phosphors that emit red light when excited by the absorption of ir radiation. A number of processes are important in suppressing the green emission normally seen in erbium-ytterbium double-doped phosphors, and in emphasizing the often weak red emission. These processes…
Simplified structural models for mullite were investigated, and ir frequencies were calculated for the simplest model which gave the theoretical number of ir‐active frequencies compatible with the observed spectrum. This model, which consists of independently vibrating structural units, gives plausible frequency assig…
Beta alumina (Na 2 O·11 Al 2 O 3 ) with addition of MgO, NiO, ZnO, CuO and CaO, respectively, together with Na 2 O are sintered. Ionic conduction of Na + and X-ray diffraction of these samples are investigated. Additions of above divalent ions, except for Ca 2+ , increase the amount of Na + in β-alumina, leading to an…
Abstract The radiation damage of electron irradiated organic compounds (paraffin, tetracene) was investigated in the temperature range 300 - 4 K. The radiation damage was measured by the decrease of diffraction intensities or the contrast of extinction contours. The damage of the crystals at 4 K required considerable…