Materials Literature
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A phenomenological theory that describes the phase transitions from a liquid of achiral molecules to the periodic antiferroelectric mesophases is presented. The transitions are shown to be driven by the vector-wave condensation mechanism. Resulting ordered phases have the structure of a vector wave with linear, circul…
Vanadium oxide thin films were prepared by chemical vapor deposition using as precursors a series of vanadyl complexes of general formula , where L is a β‐diketonate ligand. The depositions were carried out on substrates in , , and atmospheres. In order to elucidate the role played by different ligands and synthesis c…
The thermal oxidation of silicon is normally considered to occur via two different routes. At higher O 2 pressures and lower temperature SiO 2 (s) film growth occurs ("passive" oxidation), while at lower O 2 pressures and higher temperature SiO(g) is desorbed in an etching process ("active" oxidation). We have measure…
Crack‐free, undoped PbTiO 3 ceramics were fabricated successfully using sol–gel‐synthesized powder prepared from chelated titanium alkoxide and lead acetate. The sintered ceramics, 8.3 mm in diameter and 6–8 mm thick, were 96% dense. In the present study, PbTiO 3 ceramics with excess lead (Pb:Ti = 1.1:1.0) had large g…
We have fabricated a new magnet with nominal composition of Sm(CobalFe0.1Cu0.078Zr0.033)8.3, which has a room temperature intrinsic coercivity Hci of 40 kOe and a saturation magnetization Ms of 92 emu/g. The new magnet has a temperature coefficient of intrinsic coercivity β(RT−773 K)=−0.15%/K and a high intrinsic coer…
One method for influencing the polarization of light is the use of wire-grid polarizers. For the visible region, this type of element can be realized as a metal-stripe grating with periods less than the wavelength. We fabricate metal-stripe gratings with periods down to 190 nm in thin chromium layers of 35-nm thicknes…
Molecular-crystal precursor states: Molecular dynamics in the nanosecond timescale shows how acetic acid molecules aggregate (see figure for one example) out of a solution in a nonpolar solvent. Is this demixing into a microemulsion the first stage of crystal nucleation?
Abstract A new method is proposed for applying the chlorite geothermometer using X-ray diffraction (XRD) data. A linear correlation has been found between the (001) basal spacing of chlorite and its “crystallization” temperature. The basal spacing values were corrected for an increase of Al(IV) with Fe enrichment (Fe/…
Abstract In this work the interfacial properties of polyester/vegetable fiber composites were analyzed by flexural testing. The compressive/tensile (σ) and shear (τ) stresses were determined for each composite in function of the span‐to‐depth ratio (λ). The general behavior of the composites was similar to that of com…
Abstract Palygorskite and sepiolite show a high sorption capacity for organic molecules. Adsorption of 2 organic cations, methylene blue (MB) and crystal violet (CV), by palygorskite and sepiolite were examined. The maximum sorption of MB and CV far exceeded the cation exchange capacity (CEC) of these minerals. This s…
The bonding of H to Fe is analyzed using qualitative band structure calculations in the framework of extended Hückel tight-binding theory and the ASED-MO cluster method. The changes in the electronic structure of bcc Fe upon the introduction of H at a vacancy are addressed, and a comparison drawn with H adsorption at…
The phase behavior of an aqueous suspension of rodlike tobacco mosaic viruses is investigated theoretically as a function of the virus density and the concentration of added salt. The total free energy involves ``volume terms'' from the microscopic counter- and co-ions and an effective pair interaction between the col…
A series of soluble low molecular weight poly( p -phenylene)s (PPP) has been synthesized by an excess polycondensation with the Suzuki coupling method. The reaction mixture therefore only contains oligomers of an odd number of phenylene units which are terminated by bromine atoms. The mixture has been preparatively se…
The catalytic subunit of protein serine/threonine phosphatase 4 (PP4C) has greater than 65% amino acid identity to the catalytic subunit of protein phosphatase 2A (PP2AC). Despite this high homology, PP4 does not appear to associate with known PP2A regulatory subunits. As a first step toward characterization of PP4 ho…
The appearance of a toroidal moment is observed in the magnetoelectric Cr 2 O 3 in a strong magnetic field above the spin-flop transition field. This conclusion is based on the experimentally established fact that the off-diagonal components of the magnetoelectric susceptibility tensor of Cr 2 O 3 contains an antisymm…
Oxygen adsorption in an ordered $p(1\ifmmode\times\else\texttimes\fi{}1)$ fashion on the Fe(001) surface has been studied by empty states spectroscopies using a spin-polarized electron beam. The low-energy electron absorption and reflection display a much larger spin dependence in Fe(001)-$p(1\ifmmode\times\else\textt…
The reactivities of four hydratable aluminas were investigated. Rates of heat liberation during hydration from 15° to 55°C were determined by isothermal calorimetry. Rates of heat evolution show two peaks. An initial mixing peak is due to wetting and initial dissolution reactions. A second, main heat peak is associate…
Using inelastic neutron scattering, we have measured a range of amorphous forms of ice, including high-density and low-density amorphous ices, in the energy transfer region from 2 to 500 meV (16--4033 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$). The measured spectra show that the pressure-produced high-density amorpho…
Photoelectrochemical characterization of semiconducting diamond was carried out in a weakly UV‐absorbing aqueous electrolyte using suprabandgap illumination in order to examine the influence of electrochemical oxidative surface treatment on the energetic positions of bandedges. Anodic treatment of diamond photoelectro…
This paper reports the first single-crystal Raman spectra of substituted barium hexaferrites, BaFe12−2x MexCoxO19 (Me=Ir, Ti). The spectra were investigated in the 200–900 cm−1 range and are discussed in comparison with unsubstituted barium hexaferrite. Emphasis was placed on the different factors influencing the Rama…