Materials Literature
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A simple model for the rheological behavior of concentrated colloidal dispersions is developed. For a suspension of Brownian hard spheres there are two contributions to the macroscopic stress: a hydrodynamic and a Brownian stress. For small departures from equilibrium, the hydrodynamic contribution is purely dissipati…
Polarized Raman-scattering spectra are obtained from oriented single crystals of ${\mathrm{CeO}}_{2}$. Second-order features are assigned to phonon overtones from the X and L points on the Brillouin-zone boundary on the basis of selection rules and by analogy to another fluorite structure compound, ${\mathrm{BaF}}_{2}…
The structural and functional roles of threonine-23 in the chicken muscle adenylate kinase (AK) were investigated by site-directed mutagenesis coupled with proton nuclear magnetic resonance (NMR) and phosphorus stereochemistry. The residue is potentially important because it is conserved among all types of AK and is p…
Early stages of diamond film deposition on molybdenum substrates using dc arc discharge in CH4/H2 gas mixtures were studied by in situ measurements of optical reflectivity of growing film. Ultrafine diamond grit of ≊200 Å size was used for seeding to increase nucleation density up to 2×109 cm−2 and to produce smooth t…
Temperature hysteresis is theoretically studied for the volume phase transition of chemically cross-linked gels. The condition of the appearance of a ``surface skin layer'' of new phase is formulated and calculated. The result predicts that the surface skin layer is destabilized near the critical point of the transiti…
Epitaxial (001) diamond film were grown on mirror-polished single-crystalline (001) silicon substrates by microwave plasma chemical vapor deposition from a methane/hydrogen gas mixture. The films were characterized by means of scanning electron microscopy, Raman spectroscopy, and x-ray analysis. The results show that…
We have found that diamond can be synthesized from a mixture of CH4 and N2 without adding any H2. This new synthesis is sharply different from the common practice of diamond growth by chemical vapor deposition, which uses a hydrogen-rich mixture of CH4 and H2. In this new approach, nitrogen becomes an active component…
The crystal structure of a stable silyl cation, triethylsilylium, in the form of its tetrakis (pentafluorophenyl)borate salt [Et(3)Si(+) (C(6)F(5))(4)B(-)] (Et, ethyl) shows no coordination between cation and anion. The closest silicon-fluorine distance is greater than 4 angstroms. A toluene solvent molecule is close…
In dielectric multilayer optical coatings, laser induced damage is often associated with micrometers -scale surface defects such as the well known nodule defect. The interaction mechanism of the laser light with the coating defects is not understood, however. Historically, laser damage has been associated with peaks i…
Barium titanate thin films were deposited on metallic conducting BaPbO3 ceramic substrates by the sol-gel method using metal alkoxides. The thin films with a thickness of around 0.4 μm were confirmed to have a perovskite structure and to be highly resistive with a resistivity of more than 1011 Ω cm at room temperature…
The complex dielectric constant of ${\mathrm{Rb}}_{0.40}$(${\mathrm{ND}}_{4}$${)}_{0.60}$${\mathrm{D}}_{2}$${\mathrm{PO}}_{4}$ has been measured in the frequency interval from 1 mHz to 1 GHz at temperatures between 40 and 140 K. A novel frequency-temperature plot of the data is introduced to show that the behavior of…
Studies of icosahedral quasicrystals have revealed a conductivity pseudogap much narrower than the density-of-states pseudogap, resulting in a rapid suppression of electron diffusivity inside the latter. In contrast, measurements of the new metallic compounds ${\mathrm{Al}}_{2}$Ru show the formation of a semiconductin…
Discusses the three-stage numerical exposition of the effects of quenched disorder on phase ordering dynamics. The authors study the effects of random fields on domain growth. The numerical results indicate that the domain growth law is logarithmic for both the cases with non-conserve and conserved order parameter. Th…
A family of quasicrystals of dimensions 1, 2, 3, 4 governed by the root lattice E 8 is constructed. The use of the icosian ring, found in the quaternions with coefficients in Q( square root 5), allows simultaneous interpretation of the construction both in physical space and as a result of the standard 'cut-and-projec…
The conductivity \ensuremath{\sigma} of a series of AlCuFe and AlPdMn quasicrystals and approximant phases can be written \ensuremath{\sigma}(T)=${\mathrm{\ensuremath{\sigma}}}_{4}$ K+\ensuremath{\delta}\ensuremath{\sigma}(T). The ${\mathrm{\ensuremath{\sigma}}}_{4\mathrm{}\mathrm{K}}$ term is very low, decreases with…
The luminescence behavior of thermally oxidized porous silicon has been examined at various temperatures and times. No blue shifting of the photoluminescence has been noted with extended oxidation time (3–120 min), in a range where a 30% oxide thickness increase has been reported. This result does not easily fit the q…
The optical functions of several forms of thin-film silicon (amorphous Si, fine-grain polycrystalline Si, and large-grain polycrystalline Si) grown on oxidized Si have been determined using 2-channel spectroscopic polarization modulation ellipsometry from 240 to 840 nm (∼1.5–5.2 eV). It is shown that the standard tech…
The temperature dependence of the Vickers hardness is measured on the basal (0001) plane of single crystal α-Al2O3 (sapphire) from room temperature to 1273 K. The plastic zone surrounding the indents is investigated using selective chemical polishing and etching, optical microscopy, and transmission electron microscop…
A reference that offers comprehensive discussions on every important aspect of aluminum bonding for each level of manufacturing from mill finished to deoxidized, conversion coated, anodized, and painted surfaces and provides an extensive, up-to-date review of adhesion science, covering all significa
The electric field present in an inisotropic medium confined in a spherical cavity within an isotropic medium has been calculated. We considered a nematic liquid crystal with a cylindrically symmetrical director configuration with the symmetry axis along the direction of an applied a.c. electric field. The mesophase a…