Materials Literature
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We report on the proton spin–lattice relaxation measurements in the isotropic and nematic phases of the liquid crystal 4′-pentyl-4-cyanobiphenyl (5CB), constrained by a low-concentration polymer network. Above the nematic–isotropic transition, a relatively small impact of the network in the MHz regime and a huge incre…
Optical study of trivalent 3 d transition metal oxide compounds LaSr M O 4 ( M =Cr, Mn, Fe and Co) with layered perovskite structure has revealed fundamental features of their electronic structures. Systematic change of the charge-transfer gap ( E gap ) with the 3 d element ( M ) can be explained by a simple ionic mod…
Spectra of optical absorption (3 eV ∼ 6 eV) and emission (2.9 eV ∼ 4.1 eV) have been investigated on Ce 3+ centres in YAlO 3 :Ce 3+ single crystals at 297 K; excitation spectrum for 360 nm light in the Ce 3+ emission band region has also been measured in the region of 3.5 eV ∼ 6.2 eV. Measurement of excitation spectru…
Abstract Synthesis of 1,5‐bis(4‐fluorobenzoyl)‐2,6‐dimethylnaphthalene ( 1 ), polycondensation of 1 with Bisphenol A, and properties of the obtained polymer were studied. Friedel–Crafts acylation of 2,6‐dimethylnaphthalene with 4‐fluorobenzoyl chloride in nitrobenzene selectivity afforded 1 in 82% yield. X‐ray single…
An 18-site, three-ring model has been developed for the van der Waals system ortho-terphenyl (OTP) which has been studied extensively experimentally because of its glass forming ability. The method of constraints has been used to freeze out the fast internal modes of the molecule, but the model retains some internal m…
Atomic-scale images of the (001) surface of monoclinic ${\mathrm{WO}}_{3}$ have been obtained by scanning tunneling microscopy. Termination of the surface ${\mathrm{WO}}_{2}$ plane with half a monolayer of oxygen ions gives a surface periodicity \ensuremath{\surd}2 times that of the underlying ${\mathrm{ReO}}_{3}$-lik…
Abstract Surface graft polymerization of glycidyl methacrylate (GMA) was carried out onto a high‐ density polyethylene (PE) sheet pretreated with corona to introduce peroxides onto the PE surface. Graft polymerization of GMA was effected by UV irradiation of the coronatreated PE in the presence of monomer solution wit…
The structure of the title compound, CsLiB 6 O 10 , comprises eight-coordinate Cs atoms and four-coordinate Li atoms, and an anion network of chains formed from B 3 O 7 groups. The Cs and Li atoms occupy alternate sites in the channel along the c axis.
Phonon spectra for graphitic sheets of carbon, BN, and ${\mathrm{BC}}_{2}$N are computed and studied. The dynamical matrices are constructed from force constants obtained by performing supercell Hellmann-Feynman force calculations within the framework of the local-density approximation. The calculated phonon dispersio…
We report the experimental investigation of the optical properties of porous silicon embedded in a planar microcavity structure in which both the active layer and the two Bragg reflectors are fabricated by electrochemical processing of a p-type porous silicon wafer. By tuning the cavity resonance energy around the max…
The kinetics of carbon nanotube growth under arc discharge conditions were investigated over different length and time scales using complementary numerical techniques. Relaxation by ab initio molecular dynamics (Car-Parrinello method) shows that large electric fields present at the tube tips are not the critical facto…
A detailed study of the properties of ${\mathrm{Pr}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ca}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ shows that for a range of compositions (0.3\ensuremath{\le}x0.5) there is a first-order magnetic-field-induced insulator-metal transition. For the x=0.4 composition the magnetic an…
The optical properties (interband and intraband absorption) of a recently proposed structure---twinning superlattices---in diamond-type and zinc-blende-type semiconductors are calculated and discussed. The conduction-band intraband absorption is found to be rather weak, but the intraband absorption between the valence…
The dependence of the nonlinear refractive index n2 on glass compositions for optical fibers is clarified. The relation between n2 and germanium- or fluorine-doped SiO2 is calculated on the basis of the measurement of n2 at 1.55 μm with the improved cross-phase-modulation method, taking into account the radial distrib…
Magnetic properties of carbon nanotubes (CN's) are studied in a k · p model. In a magnetic field perpendicular to the tube axis, the magnetization is essentially determined by that of a graphite sheet, while it is induced also by the Aharonov-Bohm (AB) effect in a parallel field. The AB effect manifests itself in the…
Recently, octahedron structures have been found in the Czochralski-silicon substrate surface layer just under the oxide defects. An attempt is made to characterize these structures by analysis with transmission electron microscopy and energy-dispersive x-ray spectroscopy. Several results indicate that the structure is…
We relate the static conductivity of carbon nanotubes to the static in-plane conductivity of a graphite sheet and conclude that isolated single-wall nanotubes are excellent conductors. In contrast, multiwall tubes at low doping may possess conductivities substantially below that of the sum of the constituent tubes. Th…
We have studied metallic ${\mathrm{SrVO}}_{3}$ and ${\mathrm{CaVO}}_{3}$ by inverse photoemission and high-resolution photoemission. In going from Sr to Ca, considerable spectral weight is transferred from the coherent band to the upper and lower Hubbard bands. Meanwhile, the overall intensity rather than the width of…
The electronic structure of ${\mathrm{PrNiO}}_{3}$ has been studied by photoemission and x-ray-absorption spectroscopy. By analyzing the spectra using configuration-interaction calculations on a ${\mathrm{NiO}}_{6}$ cluster model, it has been found that the charge-transfer energy \ensuremath{\Delta} is \ensuremath{\si…
Statics of 90° domain structures formed in a thin tetragonal film epitaxially grown on a cubic substrate is studied theoretically on the basis of a rigorous solution of the associated elasticity problem. Inhomogeneous internal stresses existing in the strained polydomain epitaxy are calculated by the method of fictiti…