Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Absolute total electron scattering cross sections for molecular oxygen have been measured at low electron energies using a photoelectron source. The measurements have been carried out at 38 electron energies varying from 0.15-10 eV with an accuracy of +or-2.7%. The cross sections obtained in the present experiment hav…
Spectroscopy of organic molecular glasses and cold-deposited films is reviewed. The emphasis is on demonstration of the capabilities of such Spectroscopy in tackling the fundamental problems in the physics of the amorphous state. It is shown that in discussing the structural properties a considerable amount of informa…
Microcrystalline Sm-Fe-V magnets with a ThMn12 crystal structure were prepared by mechanical alloying and a subsequent reaction heat treatment. In Sm15Fe70V15 a coercivity of 11.7 kOe is obtained. This is the best value reported so far for 1:12 magnets. As expected from their high anisotropy fields, the 1:12 magnets,…
The local potential created by photoexcited electron-hole pairs at the surface of clean and partially oxidized Si(111)-(7\ifmmode\times\else\texttimes\fi{}7) surfaces is probed with a scanning tunneling microscope. Strong reductions in the surface photovoltage on the 15--20-A\r{} length scale are observed due to local…
Photoluminescence has been observed in the energy range 0.7 to 0.9 eV in short-period Si/Ge strained-layer superlattices grown on Si(100) and Ge(100) substrates. The luminescence is strongly influenced by period, layer-thickness ratio, and strain distribution. The experimental results are in good agreement with the ex…
Abstract The problem of the electronic structure of solid matter is addressed in terms of multiple scattering theory, starting from a short review of local density functional theories, the properties of Schrodinger and Dirac Hamiltonians for a central field, and resolvents and Green functions. Throughout this book, bo…
Abstract The isothermal crystallization of unreinforced poly(phenylene sulfide) (PPS) and PPS filled with glass, carbon, and aramid fibers was studied by differential scanning calorimetry. The Avrami exponent and rate constant are reported, but the crystallization half‐times were used to compare the effects of differe…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProgress with Laue diffraction studies on protein and virus crystalsJanos Hajdu and Louise N. JohnsonCite this: Biochemistry 1990, 29, 7, 1669–1678Publication Date (Print):February 20, 1990Publication History Published online1 May 2002Published inissue 20 February 1990https:…
Abstract The isothermal cure of a diglycidyl ether of bisphenol A with a tetrafunctional aromatic diamine has been studied in an attempt to achieve full cure (maximum glass transition temperature, T g ∞ , ca. 170°C). Since high temperatures of cure are necessary for high T g ∞ systems (because of low reaction rates af…
Abstract The effects of solvent size, temperature, and polymer molecular weight on the swelling of poly(methyl methacrylate) (PMMA) thin films in low molecular weight alcohols were investigated using an in situ ellipsometer. Apparent activation energies were indicative of non‐Fickian diffusion, although optical data s…
Neutron spectroscopy has been performed on a sample of PuO 2 , enriched to 94% with the non-absorbing isotope 242 Pu, to measure the crystal-field potential. The authors find levels consistent with the weak-field case crystal-field parameters recently derived for UO 2 and NpO 2 , but inconsistent with a weak-field int…
High-resolution neutron powder diffraction studies were performed on several compounds of the type YFe 12-x Al x (x=8, 7, 6). The authors observed a strong preferential site occupation of Fe on one of the three non-equivalent transition metal sites of the hMn 12 -type structure. In particular the 8f site is found to b…
Symmetry arguments are used to classify the various modes of instabilities of one-dimensional periodic patterns. An important feature of this theory is to point out the coupling between these modes and the phase of the cellular structure. A number of results presented allow to interpret recent observations in hydrodyn…
An optical study of the smectic-O films which float on the free surface of droplets of racemate MHTAC [1(methyl)-heptyl-terephtalidene-bis-amino cinnamate] in the isotropic phase, is presented. It allows us to elucidate the herringbone structure of the molecules in this original liquid-crystal phase, and to estimate t…
Third-order optical susceptibilities (χ(3)) of poly{(7-oxo-7, 10H-benz[de]imidazo[4′,5′:5,6]benzimidazo [2,1-a]isoquinoline-3,4:10,11-tetrayl)-carbonyl}, referred to as BBL, and poly(6,9-dihydro-6,9-dioxobisbenzimidazo[2,1b:1′,2′j] benzo[1mn]-[3,8]phenanthroline-3,12-diyl), known as BBB, have been determined using the…
Indium tin oxide films are prepared by in-situ evaporation in a partial vacuum with varying compositions of indium to tin and the ac conductivity of these films is investigated over a frequency range of 1 to 10 kHz. The results show distinct linear regimes in the log–log plots for all compositions, suggesting hopping-…
(I) C 8 H 6 S 6 + .I 3 − cristallise dans P2 1 /c avec a=15,307, b=9,622 et c=12,013 A, β=110,69°, Z=4; affinement jusqu'a R=0,0374. (II) C 7 H 4 S 6 + .I 3 − cristallise dans P2 1 /c avec a=14,583, b=9,350 et c=11,995 A, β=107,76, Z=4; affinement jusqu'a R=0,0301. Les deux sels sont isostructuraux l'empilement compre…
Amorphous C-Ge multilayers have been produced with periods varying from 2.6 to 12.5 nm. We have studied the multilayers using Raman spectroscopy and dc conductivity measurements and found that their properties change significantly when the carbon sublayer thickness is smaller than 2.5 nm. This value corresponds to the…
This work reports on the result of electrical conductivity measurements carried out on coconut-shell activated carbon. The results suggest that the charge carriers moved by variable-range hopping below 200 K, by hopping among localized energy states between 200 K and 385 K, and by percolation through energy states clo…
Tetragonal-to-orthorhombic phase transition at about 410 K is found by a X-ray powder diffraction study on the title oxide synthesized in a lamp-image floating zone furnace. The crystal structures of tetragonal and orthorhombic forms of the oxide are determined carefully by X-ray and neutron single crystal diffraction…