Materials Literature
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Earlier results had indicated, under some conditions, a discrepancy between the observed spectral distribution of phonons produced by the heat-pulse method and the distribution predicted by the acoustic-mismatch model. Through additional measurements of the film temperature we show that the discrepancy can be resolved…
The structure of orthorhombic hexachloroethane has been refined at 294 and 140 K. At room temperature 983 symmetry-independent reflections were measured on a four-circle neutron diffractometer. The final R(F) was 0..066 including an isotropic extinction parameter. At 140 K 793 symmetry-independent reflections refined…
A many-body system sliding at constant center-of-mass velocity relative to an external periodic potential (e.g., due to the channels in which the ions move in an ionic conductor) is studied as a possible model for dynamical friction and as a model for electrical conduction in superionic conductors and systems containi…
Wakabayashi et al. fitted a force-constant model to the purely transverse phonon dispersion curves from their neutron scattering measurements on $1T$-Ti${\mathrm{Se}}_{2}$. Their model is extended here to fit the remaining phonon branches observed by them and the LA branch in the $c$ direction studied by Stirling et a…
We have measured the magnetic susceptibility of alkali-graphite intercalation compounds for $\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}$ parallel to the hexagonal $\stackrel{\ensuremath{\rightarrow}}{\mathrm{c}}$ axis (${\ensuremath{\chi}}^{c}$) and for $\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}\ensuremath{…
In this paper the first magnetic-susceptibility results for a fluid metal are reported, which cover a wide range of expansion between the normal melting point and conditions near the critical point. Measurements have been performed for fluid Cs at saturation conditions up to 1680\ifmmode^\circ\else\textdegree\fi{}C an…
We perform an analysis of the \ensuremath{\sim} 1500 ${\mathrm{cm}}^{\ensuremath{-}1}$ Breit-Wigner interference feature in the Raman spectra of stage-1 (${\mathrm{C}}_{8}X$, $X=\mathrm{K},\phantom{\rule{0ex}{0ex}}\mathrm{R}\mathrm{b},\phantom{\rule{0ex}{0ex}}\mathrm{C}\mathrm{s}$) graphite-alkali-metal intercalation…
A method is described for quantitative analysis of low-energy-electron diffraction (LEED) intensity-energy spectra by comparison of experimental spectra with spectra calculated using a dynamic theory of LEED. The method involves a minimization of the variance of the fit between experimental and calculated spectra as a…
Abstract Dynamic mechanical measurements have been made on a 4,4′‐diaminodiphenyl sulfone‐cured tetraglycidyl 4,4′‐diaminodiphenylmethane epoxy (TGDDM‐DDS). There are basically three transitions on the mechanical spectra that have been identified, and the effects of moisture uptake and amount of DDS on these transitio…
A theory of the magnetoresistance of disordered carbons is presented and applied to experimental results on carbon fibers and glassy carbon. The important features of the model include (a) a two-dimensional band structure and density of states, (b) a shallow acceptor level due to defects, (c) collision-broadened Landa…
We have examined the (001) and (110) faces of Ti${\mathrm{O}}_{2}$ (rutile) using ultraviolet photoelectron spectroscopy (UPS), low-energy-electron diffraction (LEED), and Auger electron spectroscopy (AES). We found that the (001) surface is unstable and reconstructs or facets when annealed while the (110) surface is…
The orbital magnetic susceptibility (${\ensuremath{\chi}}_{or}^{c}$) of graphite intercalation compounds is calculated for $\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}\ensuremath{\parallel}\stackrel{\ensuremath{\rightarrow}}{\mathrm{c}}$ using a tight-binding model for the $\ensuremath{\pi}$-electron energy bands…
Debye-Waller factors in the extended x-ray absorption fine structure (EXAFS) are related to the mean-square fluctuations in interatomic distances, ${\ensuremath{\sigma}}_{R}^{2}$. Monte Carlo calculations of ${\ensuremath{\sigma}}_{R}^{2}$ based on lattice-dynamical models are presented for crystalline Cu, Fe, and Pt.…
Dielectric constants and AC resistivities of rutile (TiO 2 ) doped with chromia (Cr 2 O 3 ) have been measured as a function of frequency in the range 30 Hz to 60 kHz over the temperature range 201 to 333K. Measurements of DC resistivities in the temperature region 77 to 273K have also been made. The specimens were pr…
Neutron inelastic scattering experiments have been performed on polycrystalline samples of the cerium monopnictides CeX (X=P, As, Sb, Bi). The energy-level structure of the lowest multiplet 2 F 5/2 of the Ce 3+ ion has been determined at temperatures below 293K. The level splitting can be reproduced by a single-ion Ha…
Abstract The synthesis of a series of polyguanidinium salts of potential interest as anion complexones is described. Among the various synthetic methods investigated, the polyguanidinium salts were found to be most conveniently prepared from polyamines via polynitroguanidine intermediates. The complexation of phosphat…
About the Stereospecific α‐Alkylation of β‐Hydroxyesters It was found, that dianions derived from β‐hydroxyesters with lithium diisopropylamide (LDA) at −50 to −20° were alkylated stereospecifically ( Scheme 1 ). The stereospecificity was 95–98%, the threo ‐compound ( threo ‐2, ‐3 and ‐4) being the main product. This…
Coherent electric echo magnitudes and decay rates have been studied systematically in four silica glasses with differing OH concentrations at a frequency of 0.7 GHz and to temperatures as low as 19 mK. Echoes have been observed in glasses with negligible OH content and originate from intrinsic tunneling systems posses…
A laser-induced luminescence technique is introduced for probing the structure and equilibria of lanthanide complexes and lanthanide ion binding to macromolecules. The method involves the excitation of the 7F0 leads to 5D0 transition between nondegenerate levels in the europium(III) ion by means of an intense pulsed d…
The concept of a coating with a built in vulnerability to destruction by specific reagents has been used successfully in some applications. For example, floor finishes which can be removed readily when renewal is required by the application of dilute ammonia, or another mild reagent, are available and convenient. The…