Materials Literature
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We report the first room-temperature sharp line electroluminescence of an erbium-doped silicon light-emitting diode at λ=1.54 μm. The electroluminescence originates from an internal f-shell transition of Er3+. The wavelength and linewidth are relatively independent of temperature. The light intensity saturates at a dr…
The electronic and structural properties of ${\mathrm{VO}}_{2}$ across its metal-insulator transition are studied using the local-density approximation. Band theory finds a monoclinic distorted ground state in good agreement with experiment, and an almost open gap to charge excitations. Although rigid criteria for dis…
A new class of porphyrin-based chromophore systems has been prepared from ethyne-elaborated porphyrin synthons through the use of metal-mediated cross-coupling methodologies. These systems feature porphyrin chromophores wired together through single ethynyl linkages. This type of topological connectivity affords excep…
Abstract Cyclotrimerization of phenyl isocyanate in the presence of various catalysts was studied. All reactions were carried out in 1,4‐dioxane at 30–50°C. Reaction products were determined by reverse‐phase liquid chromatography. 1,3,5‐Triphenyl isocyanurate was formed and also traces of 1,3‐diphenylurea and 1,3,5‐tr…
Reorientations of Fe3+ spins have been studied in TbFeO3 single-crystal absorbers by Mossbauer spectroscopy. At low temperature we observed two closely spaced changes of direction of the Fe3+ spins. Below 6.5 K the spins moved from the a towards the c orthorhombic axis with decreasing temperature. This movement was re…
The crystal structures and Mössbauer spectra of various mixed oxides LaFe1−xMnxO3 and LaFe1−xCoxO3 (x = 0 to 0.9) are determined and measured at room temperature. The results indicate that the crystal structure of both the La–Fe–Mn–O and the La–Fe–Co–O systems vary with the relative content of manganese and cobalt in…
Neutron diffraction experiments over the momentum transfer range 0<Q(AA) -1 <40 have been used to investigate the structural properties of liquid sulphur from 140 degrees C up to 300 degrees C, i.e. from conditions near the melting point of sulphur up to temperatures well above its lambda -transition (T lambda =159 de…
Abstract Morphology–property relationships for simultaneously biaxially stretched films and heatset with fixed dimensions in the temperature range of 100–240°C have been studied. The observed transition in various properties at 180°C can be explained on the basis of microstructural changes caused by competition among…
Heteroepitaxial growth of tin-doped indium oxide (ITO) film was achieved for the first time by using single crystalline yttria stabilized zirconia (YSZ) as substrates. The epitaxial relationship between ITO film and YSZ substrate was ITO[100]∥YSZ[100]. By comparing the electrical properties of this epitaxial ITO film…
We propose a mechanism for creating lateral order in thin films of a homopolymer mixture via spinodal decomposition in the presence of a laterally structured substrate surface. The system under consideration is a mixture of deuterated polystyrene and partially brominated polystyrene (PBrxS, x=0.5) spuncast onto differ…
Abstract Three conventional polyurethane (PU) elastomers were blended physically with various ratios of high molecular weight of poly(4,4′‐diphenylsulfone terephthalamide) (PSA) to form 12 PU/PSA polyblends in order to modify their physical properties. Also three new polyurethanes were synthesized with a low‐molecular…
Abstract Polyurethanes were synthesized from polyester polyols, derived from PET Waste. The PET waste was first depolymerized by glycolysis. The glycolysized products were reacted with adipic acid to yield polyester polyols, and the polyester polyols were then reacted with either MDI or TDI to obtain polyurethanes. In…
Deep level transient spectroscopy (DLTS) has been used to investigate trap levels in sol-gel derived polycrystalline Pb(Zr0.54,Ti0.46)O3 thin films. Metal-ferroelectric-metal capacitor structures 2400 and 3000 Å in thickness were fabricated and characterized using a constant voltage DLTS system. Prominent peaks associ…
Transparent conducting cadmium oxide films are prepared by the spray pyrolytic technique. The dependence of structural, optical, and electrical properties on the film thickness is investigated. X-ray diffraction studies confirm the polycrystallinity of the films and the films show preferential orientation along the (2…
A diamond field emitter array has been fabricated. by Chemical vapor deposition. Diamond was grown on an inverted pyramidal-shape Si substrate followed by removal of the substrate. The fabricated array was placed in a high vacuum pumping system with the pressure of ∼10−7 Torr and the emission current as a function of…
Pulsed laser ablation-deposition is used to produce fatigue-free La0.5Sr0.5CoO3(LSC)/ PbZr0.53Ti0.47O3 (PZT)/LSC ferroelectric capacitors on oxidized (100) Si substrates coated with a bilayer of Pt/Ti. These capacitors utilize a unique bottom electrode combination of LSC on Pt, where the LSC (a conducting oxide) acts…
Structural phase transitions are considered in which the effective ordering interaction J(R ij ) arises from local stresses induced by the ordering in cell i and propagated elastically to a distant cell j. The generalized Landau free energy functional is set up and four applications made. Firstly the origin of metasta…
The low-temperature, high magnetic field heat capacity (1.5 to 70 K and 0 to 9.85 T), dc and ac magnetic behaviors of the compound (Gd0.54Er0.46)AlNi show that field-induced magnetic entropy change is significant and almost constant over the temperature region of ∼15 to ∼45 K. The resulting temperature dependence of t…
We have fabricated high quality, dielectric Ga2O3 thin films. The films with thicknesses between 40 and 4000 Å were deposited by electron-beam evaporation using a single-crystal high purity Gd3Ga5O12 source. Metal-insulator-semiconductor (MIS) and metal-insulator-metal structures (MIM) were fabricated in order to dete…
Magnetostriction of polycrystalline Co100−xPdx alloys was measured by the strain gauge method from 4 to 300 K. The saturation magnetostriction λs=(2/3)[(ΔL/L)s∥−(ΔL/L)s⊥], where (ΔL/L)s∥ and (ΔL/L)s⊥ are the saturated values (when HE≳5 kG) of ΔL/L in fields parallel and perpendicular to sample’s length (L). λs at 4 K…