Materials Literature
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The optomechanical characteristics of oriented polymer films made from a photopolymerizable liquid crystal diacrylate (BASF LC242) were examined, with general implications for oriented films of similar materials being used and considered for display-component applications. The birefringence of these uniaxial films bef…
A two-step quench process is modeled using Cahn−Hilliard theory for symmetric binary polymer mixtures. The blend is quenched from a stable state in the one-phase region to an unstable state in the two-phase region where it undergoes spinodal decomposition. The mixture is allowed to coarsen for two different time perio…
We have studied the effect of cyclization of a linear poly(styrene- b -isoprene) PS- b -PI copolymer system on the morphology of the organized nanostructures. The linear and the cyclic copolymers have exactly the same degree of polymerization, i.e., 290 for PS and 110 for PI, corresponding to a volume fraction Φ PS =…
We report electronic structure calculations for the multiferroic ferromagnetoelectric perovskite ${\mathrm{PbFe}}_{1/2}{\mathrm{Ta}}_{1/2}{\mathrm{O}}_{3},$ within density functional theory in the local spin density approximation (LSDA) and within the LSD+U approach. Our results, corresponding to several possible crys…
Single walled carbon nanotubes (SWNT) produced by the anodic arc discharge over a range of constant background pressures of helium (100–1000 Torr) were examined under a high-resolution transmission electron microscope, and a Raman spectrometer. It was found that the average SWNT diameter is about 2 nm and fairly indep…
Powder Mn 2+ EPR spectra of 5-nm ZnS:Mn quantum dots have been analyzed in detail to account for all the observed fine spectral features. The same spectral features are observed in samples with low doping of Mn 2+ (0.003−0.008%), showing 10 weak forbidden transitions between the six-line pattern of the M S = − 1 / 2 t…
A novel mesoporous MCM-41-type of hybrid material was synthesized by co-condensation of tetraethyl orthosilicate and the chelate ligand (3-trimethoxysilylpropyl)[3-(2-pyridyl)-1-pyrazolyl]acetamide ( 1 ) in the presence of cetyltrimethylammonium bromide as template. Surfactant extraction produced hybrid mesoporous mat…
Epitaxial Ni2MnGa and Ni2Mn1.2Ga0.8 thin films have been grown by molecular beam epitaxy on GaAs (001) substrates with Sc0.3Er0.7As interlayers. Structural characterization of as-grown films confirms the epitaxially stabilized single crystal structure of the films and indicates that the films grow pseudomorphically on…
Time-resolved photoluminescence spectra after nonresonant excitation show a distinct 1s resonance, independent of the existence of bound excitons. A microscopic analysis identifies exciton and electron-hole plasma contributions. For low temperatures and low densities, the excitonic emission is extremely sensitive to d…
La(Fe x Si 1−x ) 13 and their hydrides exhibit large magnetocaloric effects due to the itinerant-electron metamagnetic transitions in a wide temperature range covering room temperature. Thermal conductivity and diffusivity of La(Fe0.88Si0.12)13 and La(Fe0.88Si0.12)13H1.0 have been investigated, together with those of…
We have succeeded in growing epitaxial films of rocksalt ${\mathrm{VO}}_{x}$ on MgO(001) substrates. The oxygen content as a function of oxygen flux was determined using ${}^{18}{\mathrm{O}}_{2}$-Rutherford backscattering spectrometry and the vanadium valence using x-ray-absorption spectroscopy. The upper and lower st…
We present one-dimensional KKR method with the aim to elucidate its linear features, particularly important in optimizing the numerical algorithms in energy bands computations. The conventional KKR equations based on the multiple scattering theory as well as novel forms of the secular matrix with nearly linear energy…
The mechanisms involved in the polarization switching process in soft and hard Pb(Zr53,Ti47)O3 (PZT) bulk ceramics were investigated through the dependency of the hysteresis loop on the frequency. In order to determine the influence of the defects on the domain switching dynamics, the samples were characterized in the…
Magnetostrictive and piezoelectric laminate composites of terfenol-D and Pb(Zr1−xTix)O3 have been studied. The magnetoelectric (ME) coefficients have been characterized for the different operational modes: (i) a longitudinally magnetized and transversely polarized longitudinal transverse (LT) mode, and (ii) a transver…
We investigate the high temperature decagonal quasicrystalline phase of Al$_{72}$Ni$_{20}$Co$_8$ using a quasilattice gas Monte-Carlo simulation. To avoid biasing towards a specific model we use an over-dense site list with a large fraction of free sites, permitting the simulation to explore an extended region of perp…
Recent experiments discovered an order-disorder transition occuring at low temperatures in large unit 1/1 cell cubic approximants of the stable Cd-based binary alloy quasicrystals. The transition is related to correlations among orientational degrees of freedom whose separations are around 12 Å. We analyze the interac…
We identify several new quasicrystal approximants in alloy systems in which quasicrystals have not been previously reported. Some occur in alloys with large size contrast between the constituent elements, either containing small Boron atoms, or large Ca/Eu atoms, leading to quasicrystal structures quite different from…
Structural and magnetic properties have been studied for polycrystalline Zn1−xTMxO, where TM (transition metal ions)=Mn, Fe, and Co. No bulk ferromagnetism was observed for single-phase materials, contrary to the existing theories. Single-phase samples demonstrate paramagnetic Curie–Weiss behavior with antiferromagnet…
Catalytic palladium (Pd) nanoparticles on electrospun copolymers of acrylonitrile and acrylic acid (PAN-AA) mats were produced via reduction of PdCl 2 with hydrazine. Fiber mats were electrospun from homogeneous solutions of PAN-AA and PdCl 2 in dimethylformamide (DMF). Pd cations were reduced to Pd metals when fiber…
Depolymerization of poly(butylene terephthalate) (PBT) waste sample was undertaken with aqueous as well as alcoholic (methanolic and ethanolic) solutions of potassium hydroxide at various temperatures (35–98°C) for various time periods (0.5–60 min) at atmospheric pressure in a batch operation. Methanolic alkaline solu…