Materials Literature
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BEARTEX is a general PC-based Windows software package for quantitative texture analysis. The 30 programs that it contains provide corrections for experimental pole figures, orientation distribution calculations from complete or incomplete pole figures for all crystal and sample symmetries down to triclinic, graphical…
It is believed that strong ferromagnetic interactions in some solids are generated by subtle interplay between quantum many-body effects and spin-independent Coulomb interactions between electrons. It is a challenging problem to verify this scenario in the Hubbard model, which is an idealized model for strongly intera…
Recently, we have been able to synthesize platinum colloidal nanoparticles of different shapes ( Science, 1996, 272, 1924). In this report, we present transmission electron microscopic (TEM) results on the time-dependent shape distribution of platinum nanoparticles during the growth period and its dependence on the co…
Models are presented which are compatible with the Rietveld method for the anisotropic broadening of the diffracted peaks produced by crystallite size and microstrain. The models, derived from general crystallographic considerations, are different for different Laue groups.
In this paper it is demonstrated in a wide stress field range that breakdown in thin oxide layers occurs as soon as a critical density of neutral electron traps in the oxide is reached. It is proven that this corresponds to a critical hole fluence, since a unique relationship between electron trap generation and hole…
We report the results of quantitative phase-field simulations of the dendritic crystallization of a pure melt in two and three dimensions. These simulations exploit a recently developed thin-interface limit of the phase-field model [A. Karma and W.-J. Rappel, Phys. Rev. E 53, R3017 (1996)], which is given here a detai…
Hydrated Na ions have been ion-exchange intercalated into the insulating layered cadmium thiophosphate to give Cd 0.75 PS 3 Na 0.5 (H 2 O) y . Intercalation occurs with a dilation of the lattice which depends on the extent of hydration of the interlamellar Na ion; for y = 1 the lattice expansion is 2.8 Å, while for y…
Two-component (bidisperse) polystyrene brushes, consisting of long and short chain populations end-tethered at a solid/liquid interface, were studied in toluene and cyclohexane solvents using neutron reflection methods. A stratification of the long and short chain components was observed under all solvent conditions,…
The review summarises and analyses recent results of studies into phase transitions in polymer solutions induced by mechanical fields. Processes of dynamic structure formation preceding phase transitions in shearing and longitudinal fields are described. The effect of molecular weight, chain flexibility, and concentra…
An extensive diffuse reflectance infrared investigation of the interaction of 12-tungstophosphoric acid (HPW) and its potassium salt with NO x ( x = 1 or 2) was performed. In the presence of KBr, HPW yielded a spectrum identical to that of the potassium salt. Using pure powders, spectra of HPW·6H 2 O showing the (O−H)…
Kentbrooksite, ideally (Na,REE)dCa,REE)6Mn3Zr3NbSi25074F2 . 2H20, is a new mineral from the Kangerdlugssuaq intrusion, East Greenland. The mineral occurs in alkaline pegmatitic bodies cutting pu- laskite rocks and is found as anhedral to subhedral aggregates up to 2 cm. It is transparent, yellow-brown withwhite streak…
The random-phase approximation is combined with the perturbed hard-sphere-chain (PHSC) equation of state for copolymer systems to represent the microphase separation transition in compressible diblock copolymer melts. The PHSC equation of state takes into account the equation-of-state effect that results from differen…
Colloidal boehmite (AlOOH) rods were used as cores for the preparation of rods with a silica shell. Via a three-step coating procedure silica rods with adjustable aspect ratios up to 20 were obtained by varying the amount of the added silica precursor tetraethoxysilane (TES). Silica rods are stable in various solvents…
The decomposition of formic acid on (2 × 2) NiO(111)/Ni(111) was studied by infrared reflection absorption spectroscopy (IRAS). Formic acid molecules adsorbed dissociatively on the surface to form formate which decomposed to H 2, CO 2, H 2 O, and CO at 340−415 and 520 K. The vacant sites after the decomposition of for…
This contribution concerns the application of the thermodynamic-integration approach to crystalline structures. We calculate the defect Helmholtz energy of a single comonomer inclusion into the crystal structure of the host polymer via molecular-dynamics simulations. It was found that prior to the commonly applied sca…
We report the preparation, single-crystal X-ray structure determination, and magnetic susceptibility measurements of a new ternary vanadium oxide, [H 2 N(CH 2 ) 4 NH 2 ]V 4 O 9 . This compound has isolated V 4 O 9 2 - layers made up of edge-sharing VO 5 square pyramids. The V 4 O 9 2 - layers of [H 2 N(CH 2 ) 4 NH 2 ]…
Silica-supported molybdenum oxide (MoO 3 /SiO 2 ) and alkali-ion-modified MoO 3 /SiO 2 samples were characterized by Mo K-edge XAFS and Raman spectroscopies. The structure of the molybdenum species in MoO 3 /SiO 2 was confirmed to be monomeric and tetrahedral, (O Mo O)O 2 . In alkali-ion-modified MoO 3 /SiO 2, the str…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSynthesis and Characterization of Mesostructured Tin Oxide with Crystalline WallsLimin Qi, Jiming Ma, Humin Cheng, and Zhenguo ZhaoView Author Information Department of Chemistry, Peking University, Beijing 100871, China Cite this: Langmuir 1998, 14, 9, 2579–2581Publication Dat…
We have developed a new model to describe the melting point depression of isomorphic copolymers. The model combines the common models applied for nonisomorphic and isomorphic copolymers and is capable of fitting the transition between both assuming the concentration dependence of the mean defect Gibbs energy. The mode…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTElectroactive Polyimides Derived from Amino-Terminated Aniline TrimerZ. Y. Wang, C. Yang, J. P. Gao, J. Lin, X. S. Meng, Y. Wei, and S. LiView Author Information Department of Chemistry, Carleton University, 1125 Colonel By Drive, O…