Materials Literature
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A simple model for the thermal conductivity of polycrystals is presented by incorporating the concept of the Kapitza resistance with an effective medium approach. By applying this model to a few thermoelectric alloys reported in the literature, we show that it quite well describes the often observed grain size-depende…
Lamellar single crystals of poly( l -lactic acid) (PLLA) were grown from a 0.05% solution of p -xylene at 90 °C. The hexagonal, truncated-lozenge and lozenge-shaped single crystals with spiral growth were prepared simultaneously, and these crystals were relatively stable under conditions of electron bombardment. The h…
The thermal expansion of NiO‐8 mol % Y 2 O 3 ‐stabilized ZrO 2 (YSZ) composites and Ni‐YSZ cermets in air and hydrogen have been investigated in the temperature range from 50 to 1000°C. The average linear thermal expansion coefficient (TEC) of NiO‐YSZ composites in air increased with NiO content over the entire compos…
Several cobalt porphyrins (CoP) have been reduced by radiation chemical, photochemical, and electrochemical methods, in aqueous and organic solvents. In aqueous solutions, the Co I P state is stable at high pH but is shorter lived in neutral and acidic solutions. Stable Co I P is also observed in organic solvents and…
Two filters for improving the visibility of crystalline material in the presence of amorphous surface contamination layers in high‐resolution electron microscope images can be constructed automatically from the information present in the Fourier transform of the recorded image. The recorded signal is considered in the…
The accuracy of XPS and AES quantification by peak shape analysis was established from a detailed analysis of a range of model spectra and three sets of experiments. It was found that information on the concentration–depth profile in the surface region up to depths of ∽5λi (where λi is the inelastic electron mean free…
The nature and the role of 1 to 5 nm thick TiO2 seed layers for the growth of textured PbTiO3 and Pb(Zr,Ti)O3 thin films on textured Pt(111) thin film substrates have been studied. Under otherwise identical in situ sputter deposition process conditions, the PbTiO3 texture could be turned from (100) to (111) orientatio…
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…