Materials Literature
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Composites of nickel and Al 2 O 3 with compositionally graded microstructures were fabricated from powders through an empirically determined thermal‐behavior‐matching process that was designed to minimize processing‐induced stresses. Compositions ranged from pure Al 2 O 3 to pure nickel. Specimen geometries included r…
The question of the equilibrium linear charge density on a charged straight conducting “wire” of finite length as its cross-sectional dimension becomes vanishingly small relative to the length is revisited in our didactic presentation. We first consider the wire as the limit of a prolate spheroidal conductor with semi…
This work includes an study of the glass windows of the "Monasterio de Pedralbes", in Barcelona, concerning lead as their main element.
High resolution data on low energy phonon branches (acoustic and soft optic) along the three principal symmetry axes in pure KTaO3 were obtained by cold neutron inelastic scattering between 10 and 80 K. Additional off-principal axis measurements were performed to characterize the dispersion anisotropy (away from the <…
To clarify the equilibrium polymerization behavior of 1,4-dioxan-2-one, PDO, bulk polymerization was investigated with Sn(II) ethylhexanoate or triethylaluminum over a range of 60−180 °C. The thermodynamic parameters Δ H ls, Δ S ls, and ceiling temperature for the polymerization were −14.1 kJ mol -1, −26.1 J mol -1 K…
In this paper, optical and vibrational properties of the FeCl 3 -doped dimer of polyaniline, a model compound of emeraldine salt are presented. This oligomer is synthesized according to the method reported by Zaghal et al.. A complete assignment of the fundamental in-plane Raman and infrared modes (1700−600 cm -1 ) of…
The layer perovskite-like structures of the so-called Ruddlesden-Popper phases have been analyzed in terms of crystal chemistry. The geometrical boundaries of the existence ranges of these compounds with multilayer stacks are determined and new phases of this type are predicted. The possible variants of related struct…
The incipient ferroelectric KTaO3 presents low-T Brillouin spectra anomalies,e.g. a broad central peak (CP), and some additional Brillouin doublets (BD), whose origin is interpreted in terms of phonon-density fluctuation processes. A parameterisation from new extensive high-resolution neutron-scattering measurements i…
Monte-Carlo simulations of a focusing supermirror guide after the monochromator on the IN14 cold neutron three-axis spectrometer, I.L.L. were carried out using the instrument simulation programs RESTRAX and McSTAS. The simulations were compared to experiment to check their accuracy. Comparisons of the flux ratios over…
Zero-field ${}^{139}\mathrm{La}$ and ${}^{55}\mathrm{Mn}$ nuclear magnetic resonances were studied in ${\mathrm{La}}_{0.8}{\mathrm{Ca}}_{0.2}{\mathrm{MnO}}_{3+\ensuremath{\delta}}$ with different oxygen stoichiometries \ensuremath{\delta}. The signal intensity, peak frequency, and line broadening of the ${}^{139}\math…
Low-frequency dielectric measurements on plexiglass (PMMA) show that cooling and heating the sample at constant rate give a hysteretic dependence on temperature of the dielectric constant . A temporary stop of cooling produces a downward relaxation of . Two main features are observed: i) when cooling is resumed goes b…
Nonlinear conduction in a single crystal of charge-ordered ${\mathrm{Pr}}_{0.63}{\mathrm{Ca}}_{0.37}{\mathrm{MnO}}_{3}$ has been investigated in an applied magnetic field. In zero field, the nonlinear conduction, which starts at $T<{T}_{\mathrm{CO}},$ can give rise to a region of negative differential resistance (N…
A systematic study of phase separation effects in polycrystalline ${\mathrm{La}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{MnO}}_{3}$ obtained under different thermal treatments is reported. Samples with average grain size ranging from 200 to 1300 nm were studied. Magnetic and electrical measurements show quantitative differen…
The crystal and magnetic structures of ${\mathrm{Tb}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ series have been studied by x-ray and neutron-diffraction techniques. Macroscopic magnetic properties have been characterized using ac magnetic susceptibility measurements. The relationships between structural…
Most cellular solids are random materials, while practically all theoretical results are for periodic models. To be able to generate theoretical results for random models, the finite element method (FEM) was used to study the elastic properties of solids with a closed-cell cellular structure. We have computed the dens…
Low-T Brillouin spectra of the incipient ferroelectric KTaO3 exhibit a broad central peak (CP), and additional Brillouin doublets (BD), that can both be related to phonon-density fluctuations. On the basis of new high-resolution neutron data obtained of low-lying phonon branches, we analysed the phonon-kinetics mechan…
The iron rust phase was analyzed by using the in-situ x-ray diffraction (XRD) and alternating current (AC) impedance methods after a wet/dry corrosion test using sodium chloride (NaCl) solution, which is the main composition of airborne saline particles. The corrosion content of the carbon steel depended on the concen…
Raman microscopy has been employed to investigate the nature of damage created when natural type-IIa diamond is irradiated with MeV alpha particles. Three features appear in the Raman spectrum due to damage, viz., (i) the first-order diamond Raman line is broadened and downshifted, (ii) broad features appear which are…
This article reviews recent developments in the polymerization of α-amino acid- N-carboxyanhydrides (NCAs) to form polypeptides. Traditional methods used to polymerize these monomers are described, and limitations in the utility of these systems for the preparation of polypeptides with controlled molecular weights and…
Several copper complexes used successfully as the catalysts for atom transfer radical polymerization (ATRP) were studied by cyclic voltammetry in acetonitrile. These complexes include CuBr or CuCl complexed by 2,2′-bipyridine (bpy), 4,4′-di(5-nonyl)-2,2′-bipyridine (dNbpy), 4,4′-di(n-nonyl)-2,2′-bipyridine (dnNbpy), N…