Materials Literature
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Sol–gel distributions at high conversions, simulated by computer with spatial constraints on the distribution of chain ends, are reported for end-linked tetrafunctional systems. The composition of the sol is found to be uniquely dependent upon the functionality f of the cross linker: for f=4, it mainly consists of lin…
High-resolution electron-energy-loss spectroscopy can be applied to insulators by use of an auxiliary electron gun. Fuchs-Kliewer phonons of the MgO(001) surface were recorded with excellent resolution (27 ${\mathrm{cm}}^{\ensuremath{-}1}$). Specular intensities were analyzed for angles of incidence from 40\ifmmode^\c…
Cristallisation dans P321 avec a=7,958 et c=4,124 A, Z=1; affinement jusqu'a R=0,020. Des colonnes infinies d'atomes Sr a coordination 9 sont placees le long des axes d'ordre 3. Trois molecules H 2 O sont coordinees equatorialement a chaque atome Si tandis que les six autres H 2 O sont egalement liees aux atomes Si ad…
The atomic arrangement in Sr3(FeF6)2 determined by von der Mühll [C. R. Acad. Sci. Paris 278, 713 (1974)] differs from a structure of opposite polarity by atomic displacements of 1.3 Å or less for F and 0.4 Å or less for Sr and Fe. The structure is hence potentially ferroelectric, with an estimated transition temperat…
Raman studies of vitreous B2O3 have been conducted between 8 and 700 K, and as a function of hydrostatic pressure (∼8 kbar) at room temperature. The low temperature Raman spectra exhibit two broad bands at 50 and 137 cm−1. From the temperature dependence of the 50 cm−1 band, it has been concluded that the vibrational…
The infrared reflectivity, the temperature-dependent conductivity, and thermopower of the one-dimensional conductor ${\mathrm{Li}}_{0.82}$[Pt${({\mathrm{S}}_{2}{\mathrm{C}}_{2}{(\mathrm{CN})}_{2})}_{2}$] \ifmmode\cdot\else\textperiodcentered\fi{} 2${\mathrm{H}}_{2}$O, LiPt(mnt), is presented. It undergoes a simple Pei…
The complex dynamical resistivity of high-quality transparent and heat-reflecting indium tin oxide films, prepared by reactive e-beam deposition, was evaluated from spectrophotometric measurements in the 0.25–50-μm wavelength range. These data are explained in detail from a theory encompassing scattering of free elect…
Magnetization measurements for the R6Fe23 (R=Y, Dy, Ho, Er, Tm, Lu) intermetallic compounds and molecular field analyses of the data are reported. A single-sublattice model accurately describes the temperature dependence of the magnetization for Y6Fe23 and Lu6Fe23. Excellent correspondence with the data for the other…
We study the $T=0$ K properties of the electron-phonon system with Coulomb interaction using a two-cutoff renormalization procedure. We find that there exist two regimes. The "classical" regime is characterized by a classical amplitude order parameter and exists when the mean-field gap (pseudogap) $\ensuremath{\Delta}…
The end linking of difunctional poly(dimethylsiloxane) with trifunctional cross linkers in the bulk has been simulated with a computer. A random array of primary chains with a Gaussian end-to-end distribution is generated in an image container on the computer. By joining chain ends at nearby junctions, inter- and intr…
We have discovered a low-lying cyclic isomer of Si–C–C which is best described as a three-membered ring with a weak carbon–carbon triple bond. In these theoretical studies a double zeta plus polarization basis set was used initially. At the self-consistent-field (SCF) and two-configuration (TC) SCF levels of theory th…
The first solubility determinations of tritium in bulk palladium are presented for the pressure range $0.016<~p<~1.33$ bars, temperature range $60<~T<~400\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, and concentration range $0.0015<~x<~0.02$ (for $x$ in $\mathrm{Pd}{\mathrm{T}}_{x}$). In addition,…
A novel technique is used in studying the energy-loss spectrum of aloof (nontouching) electrons with surfaces. Metallic foils perforated by microchannels restrict the maximum impact parameter to the channel radius (20-200 nm). The passage of electrons (20-2000 eV) near the cylinder walls results in prominent energy-lo…
SiC2 has been prepared in a supersonic molecular beam by laser vaporization of a silicon carbide rod within a pulsed supersonic nozzle. Rotational analysis of the 0-0 band of the well-known 4980 Å band system of this molecule reveals that, contrary to previous assumptions, the molecule is triangular in both the ground…
The photoelectrochemical behavior of an n-TiO2 (rutile) single crystal under different treatments (mechanical polishing and chemical and photoelectrochemical etching) is analyzed and the conditions under which Gärtner’s model can be applied are determined. The hole diffusion length Lp obtained from the photoelectroche…
Interchain hopping of bipolarons (doubly charged defects) is discussed as a mechanism for spinless conductivity in doped polyacetylene, doped $\mathrm{poly}(p\ensuremath{-}\mathrm{p}\mathrm{h}\mathrm{e}\mathrm{n}\mathrm{y}\mathrm{l}\mathrm{e}\mathrm{n}\mathrm{e})$, and other doped polymers. It is shown that this mecha…
Electrical conductivity, Seebeck-coefficient, and Hall-effect measurements have been made on single-phase boron carbides, ${\mathrm{B}}_{1\ensuremath{-}x}{\mathrm{C}}_{x}$, in the compositional range $0.1\ensuremath{\le}x\ensuremath{\le}0.2$ between room temperature and 1273 K. The results indicate that the predominan…
The author reports the observation of concerted multi-ion conduction processes in a molecular dynamics simulation of the superionic conductor lithium nitride. He identifies these processes as the soliton-like conduction mechanism, and notes that the disturbance propagates in more than one dimension.
A parameterization scheme for the electric dipole intensities of one-phonon vibronic (f-f) transitions in rare-earth (lanthanide and actinide) complexes is proposed. This parameterization is perfectly general within the one-electron, one-phonon, one-photon approximation for ion-ligand-radiation field interactions, and…
The in vitro self-assembly of murine type IV collagen was examined by using biochemical and morphological techniques. Dimeric collagen undergoes a rapid and reversible thermal gelation at neutral pH without an appreciable lag period. The process is seen to be concentration dependent and inhibited by 2 M urea. The form…