Materials Literature
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X-ray-diffuse-scattering measurements of tetrathiafulvalene tetracyanoquinodimethane (TTF-TCNQ) show structural evidence of a phase transition. The low-temperature three dimensional superlattice ($2a\ifmmode\times\else\texttimes\fi{}3.7b\ifmmode\times\else\texttimes\fi{}\mathrm{Xc}$) is found to be preceded above 40 K…
The effect of strain rate changes on the flow stress of Au–Cu alloys in the region of strain prior to the start of serrated yielding has been investigated. The measurements of Δσ/Δ Δσ/Δ were found to depend on strain, strain rate, temperature, and composition. Negative values of Δσ/Δ ln ϵ were observed prior to the on…
New oscillation phenomena in VO2 crystals were observed. The oscillation is generated in the temperature region of the crystal transition, and its voltage and frequency depend upon the ambient temperature. The waveform of the oscillation is a rectangular pulse.
The I3 C chemical shifts and 13 C– 31 P spin–spin couplings (where applicable) are reported for pyridoxine, pyridoxamine, pyridoxal, pyridoxamine phosphate, and pyridoxal phosphate. Resonance assignments are made by consideration of substituent chemical shift effects, as tested on an analogous series of pyridine deriv…
A time-dependent Landau theory is proposed for the transition-metal dichalcogenides coupling the motion of the charge-density waves to the electron liquid. The dissipative terms are related to the metallic resistance. The "phason" or "phonon" excitations of the charge-density wave are found to be overdamped. Resistive…
Transport measurements were performed on thin films of Si3N4 deposited on Si using carrier injection from low-energy corona ions and a shallow junction detector. Large hole conduction is found for both corona polarities. Examination of the electronic structure of Si3N4 by x-ray photoemission spectroscopy (XPS or ESCA)…
NMR spectra at temperatures down to 1.8 K are given for the 19F resonance of SF6 and CF4 in H2O and D2O clathrates and for the 1H resonance in CH4–D2O and CH4–tetrahydrofuran-d8–D2O clathrates. The second moments correspond effectively to isotropic reorientation of encaged SF6, CF4, and CH4 molecules at temperatures a…
High-numerical-aperature lead silicate and barium crown glass uncald fibers have been doped with cerium to decrease their radiation sensitivity. The radiation-induced optical loss in both the visible and near-infrared in these core materials has been studied as a function of time (10−3–104 sec) after pulsed irradiatio…
The amino acid salt glycine hydrochloride, H3N+⋅CH2⋅COOH⋅Cl−, crystallizes in the space group P21/c, a=7.117(2) Å, b=5.234(2) Å, c=13.745(3) Å, β=97.25(1) °. The crystal structure has been refined from three-dimensional neutron diffraction data to a final R value based on F2 of 0.058. Estimated standard deviations in…
There have been several studies of the charge transfer photochemistry of aqueous Fe 3+ but the complexity of hydrolytic equilibria and the requirement for scavengers to render the primary photochemical processes observable has left several issues moot as recent reports show. Using tert-butyl alcohol as a scavenger, it…
The thermal conductivity of a harmonic Bravais crystal containing randomly distributed substitutional defects due to impurity-phonon scattering is theoretically investigated using the methods of double-time thermal Green's functions and Kubo formalism considering nondiagonal terms in the heat-current operator as propo…
The density of valence states (DOVS) of amorphous and crystalline ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ and ${\mathrm{As}}_{2}$${\mathrm{Te}}_{3}$ and of amorphous ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ have been investigated with monochromatized x-ray photoemission spectroscopy (XPS). All three compounds exhibit sim…
The optical properties of W are presented between 0.15 and 33 eV. The optical absorptivity or reflectivity was measured at near-normal incidence, and the data were Kramers-Kronig analyzed to determine the dielectric functions. Drude parameters were determined at low energy and were used to separate interband and intra…
The theory for the spin Hamiltonian parameters of low spin cobalt(II), d 7 , complexes has been developed to third order in perturbation theory for all reasonable ground states. Two extensions beyond previous treatments have been made: (1) the spin–orbit mixing of excited quartet states into the doublet ground state h…
Resonant Raman scattering in ${\mathrm{Cu}}_{2}$O has been studied at low temperature in the vicinity of its phonon-assisted $1s$ yellow excitonic absorption edges using a cw continuously tunable dye laser. The multiphonon Raman modes which show resonance enhancement in this region are the following: ${\ensuremath{\Ga…
A Landau theory is proposed for charge-density waves (CDW) in transition-metal dichalcogenides with the charge density as an order parameter. The theory predicts the sequence of phases, normal-state---incommensurate-CDW---commensurate-CDW with decreasing temperature, separated by first-order phase transitions. The pea…
High-angular-resolution (\ensuremath{\sim}8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$ rad), high-energy (75 keV), electron scattering from graphite thin films demonstrates energy losses due to the excitation of optical surface guided modes. Measurements of the dispersion offer considerable support for…
A shallow earthquake focus mechanism is modeled by a plane strain shear crack extending at a nonuniform rate under the action of general loading. An equation of motion of the crack tip is determined in terms of a specific fracture energy, i.e., a surface energy, by applying an overall energy balance fracture criterion…
A new type of beam deflector is described which involves an electrically induced variation of the optic axis across a liquid-crystal cell. Light polarised in the plane of the optic axis can be deflected through a half-angle of 20°, with slew rates in excess of 200°/s.
A new process for preparing uranium and plutonium metals has been developed. The process is based on the high extractability of the elements with sodium amalgam from aqueous solutions. After extracting the uranium or plutonium with sodium amalgam, the resulting amalgam was heated in vacuum so that mercury and sodium w…