Materials Literature
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We present calculations of the electronic structure for higher-order rational approximations to quasicrystals up to 12 380 atoms in the unit cell, based on a tight-binding linear-muffin-tin-orbital technique. The dispersion relations of the electronic states of quasicrystals are related to those of quasiperiodic free-…
Room-temperature photoluminescence (PL) from Si chemically etched (CE) in HF-HNO3-based solution has been observed. Scanning electron microscopy reveals that the etched Si has a surface morphology similar to that of luminescent porous Si fabricated by conventional anodization. PL spectra show an order of magnitude sma…
The temperature dependence of the characteristic length for the dynamic glass transition in ortho-terphenyl is determined, for the first time, from combined results of depolarized dynamic light scattering, photon correlation spectroscopy, and viscosity experiments. The length is found to vary according to ${\ensuremat…
Structural studies on aqueous solutions of PEO-PPO-PEO block copolymers show three phases as the temperature is varied. At low T, the tri-block units are dissolved Gaussian chains. As T is increased still more unimers aggregate in micelles, until a volume fraction of 0.52 is reached. The micelles then crystallize in a…
This new study of the hard ellipsoids system by Monte Carlo simulations invalidates previous simulation work on the localization of the isotropic-nematic phase transition (Molec. Phys., 55, 1171 (1985)). The discrepancies are demonstrated to originate in size effects. Our main result is that the system of hard ellipso…
Abstract Melting parameters and transport coefficients in the melt are collated for halides of monovalent, divalent and trivalent metals. A number of systems show a deficit of entropy of melting relative to the linear relations between entropy change and relative volume change on melting that are found to be approxima…
The growing use of plastics and other flammable synthetic materials in construction, home furnishings, and various industrial applications is creating opportunities for polymer compatible, thermally stable, environmentally friendly, and cost-efficient flame retardants. New legislation emphasizing test methods that pro…
An exact relation between the bulk effective Seebeck coefficient alpha e of a composite conductor and the bulk effective electrical and thermal conductivities sigma e and gamma e is used to study the scaling behaviour of alpha e near percolation. The behaviour turns out to be quite rich, as a result of its dependence…
Copper is being considered as an alternative to aluminum-based metallizations in microelectronic circuits, both because copper is a better conductor and because it is expected to be more resistant to thermal stress and electromigration induced failure. However, thermal stresses are found to cause significant voiding i…
The dielectric constant ■ of thin epitaxial SrTiO3 films used as dielectric layers in high Tc superconducting field-effect devices has been studied. ■ in these thin films was found to have much weaker dependence on temperature and applied electric field than the bulk material. The breakdown characteristics of gate str…
The role of silicon hydride species in the photoluminescence intensity behavior of porous Si has been studied. The surfaces of luminescent porous Si samples were converted to a predominate SiH termination using a remote H plasma. The as-passivated samples were then immersed in various concentrations of hydrofluouric s…
Abstract The unusual reinforcement mechanism exhibited by silica in epoxidized natural rubber (ENR) may be attributed to the specific chemical interaction or the chemical cross‐linking taking place between silica and the epoxy groups while heating the mix. Evidence for the higher interaction is established through rhe…
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<div class="htmlview paragraph">At the 1990 Annual Aerospace/Airline Plating and Metal Finishing Forum, The Boeing Commercial Airplane Group presented information on boric acid/sulfuric acid anodizing (BSAA) as a replacement for chromic acid anodizing (CAA) to meet environmental regulations.</div> <div…
This study was undertaken to determine the cause of cracking in high hard armor steel plates used in the manufacture of light armored vehicles (LAVs) and to make recommendations to alleviate the problem. Cracks in several components from fielded vehicles were analyzed. In many cases the cracking was found to be caused…
In addition to the standard extended dislocation dipoles, we show that there are four additional stable defects with lozenge-shaped cross-sections. The relative stability of these various types of extended dipoles and faults in silver, a typical f.c.c. metal, is numerically evaluated. Isotropic linear elasticity is as…
In 1989, a 154 kV, 200 MVA gas-insulated power transformer was commissioned and has been operated with a satisfactory operating record. Utilizing this development experience and introducing new technology, a 275 kV, 300 MVA gas-insulated power transformer has been developed. The compact design of the main-gap insulati…
Na 2 HgS 2 and K 2 HgS 2 were obtained as colourless, tabular crystals by reacting the alkali sulfides Na 2 S and K 2 S with red HgS at 970 K. Both compounds are orthorhombic: Na 2 HgS 2 , oP40, s.g. Pbca with a = 18.24(2) Å, b = 7.494(5) Å, c = 7.237(5) Å, Z = 8; K 2 HgS 2 , oP20, s.g. Pbcm a = 10.697(6) Å, b = 7.958…
The structural phase transition in [N(CH3)4]2CdBr4 at 272 K has been studied by dielectric measurements. Dielectric constants along the three crystallographic axes show breaks at the transition temperature. The transition temperature increases linearly with increasing hydrostatic pressure at a rate of 0.174 K/MPa. Twi…
Several compositions were selected to investigate the formation of M phase. It was found that by reducing Fe 2 O 3 or increasing La 2 O 3 , we were able to obtain pure M phase, as deduced from X‐ray patterns, but CaO.2Fe 2 O 3 was always observed in micrographs of the polished surfaces. The instability of the M phases…