Materials Literature
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Abstract Poly(ethylene terephthalate) (PET) taken from postconsumer soft‐drink bottles was subjected to solid‐state polycondensation after cutting into small pieces or after dissolution in trifluoracetic acid, trifluoracetic acid/dichloromethane mixture (50/50%, v/v), or nitrobenzene, and coagulation in methanol. The…
The 248 nm UV photosensitivity of H2 loaded optical fibers is shown to be significantly enhanced by increasing the temperature during the UV exposure. Heating to 250–400 °C resulted in dramatic UV reaction rate increases in GeO2 doped fibers. Increasing the core temperature during 248 nm irradiation caused P2O5 doped…
Melts of many silicates are known to have an anomalous transport property in that the diffusivity of oxygen atoms drastically increases with pressure. Here we propose a mechanism for the anomalous diffusion process in liquid silica and silicates on the basis of molecular dynamics (MD) results for pressure-induced stru…
Electron beam deposition (EBD) is a maskless technique suitable for the fabrication of nanometer scale structures. Metals can be deposited from an organometallic gas, but simultaneous carbon deposition typically yields grossly impure (∼25% metal) deposits. We have found that the metal content of the deposited solid is…
We present a method for calculating the self-energy in the $\mathrm{GW}$ approximation that can be applied to systems containing $3d$ and $4f$ electrons. The method is applied to NiO and a gap of $\ensuremath{\sim}5.5$ eV is obtained, which is in reasonable agreement with the experimental value of 4.0 eV. The local de…
Three series of glassy samples are prepared by means of rapid quenching in the systems Li2OTiO2P2O5, Li2OTiO2P2O5SiO2, and Li2OTiO2P2O5SiO2V2O5. Their glass transition temperature, crystallization temperature, density, and electrical conductivity are measured by DTA, Archimedes method, and impedance spectrosc…
Single crystals of SrxBa1−xNb2O6 (SBN) with congruent composition (x = 0.61) and Sr0.61Ba0.39Nb2O6 crystals doped with various concentrations of cerium are grown with the Czochralski method. A subsequent doping of the crystals with protons and deuterons is performed either by hydrothermal high temperature treatment or…
The tracer diffusion coefficient of 44Ti in α-Fe is determined by the serial sectioning method in the temperature range of 948 to 1174 K. In paramagnetic α-Fe the diffusion coefficient of Ti shows a linear Arrhenius relationship from the α-γ transformation temperature to about 30 K above the Curie temperature TC = 104…
The optical and electrical properties of c-axis-oriented ZnO films prepared by chemical vapour deposition (CVD) in oxygen atmosphere containing water vapour are investigated. The minimum dc resistivity gives 2.20 Ω cm at a film formation temperature of 550°C. The temperature dependence of electrical conductivity for t…
The chemical species in the asymmetric unit of the title complex, [Cu(C 2 H 3 N) 4 ]PF 6 .C 2 H 3 N, consist of tetrahedral [Cu(CH 3 CN) 4 ] + cations [Cu−N 1.968 (6)-2.030 (6) A], [PF 6 ] − anions and acetonitrile solvate molecules
The diffusion constant in a silicon melt is calculated using molecular dynamics simulation based on the modified Stillinger–Weber [Phys. Rev. B 31, 5262 (1985)] interatomic potential in the temperature range 1550 K<T<1900 K. Temperature dependence of the calculated diffusion constant can be expressed usi…
We present the results of density-functional calculations of the dielectric function and the photoelastic tensor---the susceptibility for strain-induced birefringence---in GaAs for photon frequencies below the direct band gap. These calculations were performed in the Kohn-Sham local-density approximation in a pseudopo…
Crystal structure refinement of copper-bearing tourmaline from Paraiba, Brazil, rim composition {Na 0.54 Ca 0.05 } {Li 1.21 Mn 0.04 Cu 0.10 Al 1.66 } Al 6 {Si 5.92 - Al 0.08 } O 18 {BO 3 } 3 ,(OH) 3.56 F 0.44 }, core composition {Na 0.55 Ca 0.01 } {Li 1.16 Mn 0.08 Cu 0.05 Al 1.71 } Al 6 {Si 5.88 -Al 0.12 } O 18 {BO 3…
Spin-resolved x-ray photoelectron-spectroscopy (SRXPS) studies of metallic-Ni core-level and valence-band photoemission are reported. Prominent spin polarizations are observed for all main components and satellites. A spin-dependent splitting of 0.38 eV is observed for the main Ni 3s component. The Ni 3s 6-eV satellit…
Abstract Extraction and swelling experiments were carried out in order to measure the crosslinkability by dicumyl peroxide (DCP) of new homogeneous linear low‐density polyethylenes (LLDPEs) with different molecular weight, branch content, and length of branches. Considering that the tertiary radicals are most probable…
We have studied the luminescence properties of a ${\mathrm{Si}}_{8}$ cubic cluster, octasilacubane. The photoluminescence (PL) is observed around 1.7 eV at low temperatures and the PL decay is a single exponential with a time constant of 3.1 ms. The PL intensity and the PL lifetime abruptly decrease with increasing te…
Novel ring-disk ultramicroelectrodes (RD-UMEs) with analytical tip diameters as small as 25-30 microns were fabricated. Carbon RD-UMEs were reproducibly prepared by the chemical vapor deposition of alternating concentric layers of silica and carbon on resistively heated 10 microns carbon fibers. High-quality films wit…
Strained CdSe/CdS superlattices show very strong intrinsic piezoelectric fields due to the high piezoelectric constants in combination with a large lattice mismatch of 3.9%. The linear as well as the nonlinear optical properties are formed by these fields, which dominate the band structure. We report on the excitation…
Steady-state- and time-resolved-photoluminescence (PL) and cathodoluminescence (CL) studies have been carried out on several synthetic type-IIb boron-doped semiconducting diamond samples. The behavior of the 1.84-eV red donor-acceptor pair band is compared directly with that of the well-known green band-A emission nea…
This work reports a successful electron-electron coincidence experiment performed in grazing-angle reflection geometry. (e,2e) measurements with a 300-eV impact energy have been carried out on a clean highly oriented pyrolytic graphite surface and the feasibility of binding-energy spectroscopy with quasimomentum discr…