Materials Literature
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The photovoltaic (PV) power system for Space Station Freedom (SSF) uses solar array blankets which provide structural support for the solar cells and house the electrical interconnections. In the low Earth orbital (LEO) environment where SSF will be located, surfaces will be exposed to potentially damaging environment…
The electronic band structure for the ferrimagnetic state of Mn 2 Sb has been calculated using the augmented plane-wave method. The energy splitting between the spin-up and spin-down bands cannot be described by a rigid splitting of the nonmagnetic band. It has been found that the width of 3d band of Mn(II) atoms is n…
We have made carbon K edge reflectivity and absorption measurements using synchrotron radiation on diamond crystals and chemical vapor deposited diamond films to determine their electronic structures. Our spectra of diamond films show that both sp2 and sp3 bonded carbon atoms are formed during initial nucleation and g…
The temperature dependence of the nonergodicity parameter ${\mathit{f}}_{\mathit{q}}$ in the ``fragile'' glass-former propylene carbonate has been investigated using a wide-frequency-window Brillouin-scattering technique. A critical decrease of ${\mathit{f}}_{\mathit{q}}$ is revealed at temperatures well above the cal…
The mechanism of copper chemical vapor deposition from Cu(II)bis-hexafluoroacetylacetonate [Cu(hfac)2] and 1,5-cyclooctadiene-Cu(I)-hexafluoroacetylacetonate (COD-Cu-hfac) has been determined. The results explain the different processing conditions required for deposition from the precursors. Both molecules react at r…
Epitaxial BaTiO3 thin films were grown in situ on (100) LaAlO3 by low-pressure organometallic chemical vapor deposition using the precursors Ba (hexafluoroacetylacetonate)2 (tetraglyme) and titanium tetraisopropoxide. The phase composition and epitaxial quality were sensitive to the reactant partial pressures and grow…
A series of rare-earth iron carbides were prepared by heat treatment of R2Fe17 compounds in methane. The nominal composition of these carbides is R2Fe17Cx, x∼2.5. The carbides retain the original Th2Zn17 or Th2Ni17 structure with a 6.5% volume expansion over the carbon-free unit cell. For Sm2Fe17C2.5, the Curie temper…
Studying the dynamic structure factor of polybutadiene in the first valley of S(Q) we observed a decoupling of microscopic and macroscopic time scales about 40\ifmmode^\circ\else\textdegree\fi{} above ${\mathit{T}}_{\mathit{g}}$. At higher temperatures the time scale set by the viscosity scales with the microscopic sc…
The ordering in thin films of symmetric diblock copolymers has been studied by neutron reflectivity as a function of temperature and film thickness. Exponentially damped oscillatory variations in the concentration are shown to propagate into the specimens from both surfaces with decay lengths increasing with decreasin…
The discovery of luminescence in electrochemically etched porous silicon is an extremely important scientific breakthrough with enormous technological implications. It opens the door for silicon, the most important microelectronic material, as a possible material for optoelectronics applications. Our result, a correla…
Dichroism and birefringence are shown to be optically induced and erased in high-glass-transition azoaromatic polymers. The resulting polarization information is easily detected and exhibits long-term stability. This optically induced reorientation of the azoaromatic molecules will have wide applications in image reco…
Diffusion of oxygen atoms into diamond can be introduced by CrO3 treatment followed by an exposure to a hydrogen plasma. From characterization using Rutherford backscattering spectrometry, it is found that the depth distribution of the doped oxygen in the diamond is homogeneous from the surface where its concentration…
Abstract The copolymerization of acrylamide (AM) with sodium allylsulfonate (SAS) was studied. The copolymerization rate equation was determined, R p = K [KPS] 0.70 [AM] 1.60 [SAS] −0.60 . The copolymeric composition obtained by nitrogen and sulfur elemental analysis, and 1 H‐NMR method. The reactivity ratios were cal…
Abstract Thermal behavior of fluorine‐containing bismaleimides was investigated by differential scanning calorimetry and the effects of introducing fluorine groups on thermal behavior and properties of cured products were discussed. The melting point was lower and the polymerization temperature was higher with increas…
Abstract The aging of five thick‐walled natural rubber compounds has been studied by computed X‐ray tomography scanning and crosslink density measurements. The compounds were compouded as ordinary carbon‐black‐filled rubbers with sulfur and peroxide as curing agents. The rubber samples were aged in air at 70, 100, and…
Abstract Plasma polymerization of disiloxanes containing various functional groups—hexamethyldisiloxane (HMDSO), tetramethyl‐1,3‐bis(chloromethyl)‐disiloxane (CMDSO), tetramethyl‐1,3‐bis(hydroxylbutyl)‐disiloxane (HBDSO), and tetramethyl‐1,3‐bis(amino propyl)‐disiloxane (APDSO)— was carried out using an inductively co…
Abstract The polymerization of N ‐vinylcarbazole initiated with NO 2 and SO 2 in dichloroethane has been studied. The kinetics of polymerization were followed gravimetrically. The Polymerization is fast with NO 2 but a relatively slow rate was obtained with SO 2 . The polymerization with these gases appears to be init…
A procedure for generating colloidal suspensions of Si that exhibit luminescence, attributed to quantum confinement effects, is described. Samples of n- or p-type Si that have been electrochemically etched to form porous Si can be ultrasonically dispersed into methylene chloride, acetonitrile, methanol, toluene, or wa…
The performance is reported of a programmable, two-level, phase-only device based on a commercially available 128 × 128 pixellated, ferroelectric liquid crystal spatial light modulator. Near diffraction limited performance is achieved and results for a Dammann grating are comparable to those obtainable with fixed comp…
In the present paper nonlinear evolution of disturbances at the meniscus between parallel circular plates is simulated by a boundary element method. To simulate accurately such a nonlinear phenomenon, the thickness of liquid remaining on the plates is obtained numerically against the low capillary number Ca<1.0, which…