Materials Literature
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Cross-linked polyacrylonitrile PAN granules were prepared at ambient temperature by γ-rays at a constant dose rate of 8.5 kGy/h. It was found that the rate of polymerization was linear with the radiation dose at the initial stage of polymerization, and then, at high conversion, it tends to level off above 35 kGy. Cros…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTMorphological Transformation of PS-b-PEO Diblock Copolymer by Selectively Dispersed Colloidal CdS Quantum DotsSiao-Wei Yeh, Kung-Hwa Wei, Ya-Sen Sun, U-Ser Jeng, and Keng S. LiangView Author Information Department of Materials Scien…
We investigate the microdomain orientation kinetics of concentrated block copolymer solutions exposed to a dc electric field by time-resolved synchrotron small-angle X-ray scattering. As a model system, we use a lamellar polystyrene- b -polyisoprene block copolymer dissolved in toluene. Our results indicate two differ…
The isotropic–nematic phase behavior of length-polydisperse hard rods with arbitrary length distributions is calculated. Within a numerical treatment of the polydisperse Onsager model using the Gaussian trial function ansatz we determine the onset of isotropic–nematic phase separation, coming from a dilute isotropic p…
The Y2O2S:Eu phosphor has been used in fields of light sources and displays. Substituting Ti and Mg for Eu generates new energy levels between the band gap of the Y2O2S compound. As a result, yellowish-orange color emission occurs. In addition, yellowish-orange persistent phosphorescence is seen after removal of the e…
Submicrometer-sized hollow CdS spheres with a wall thickness of about 20 nm have been synthesized in aqueous solutions of cadmium acetate (Cd(OAc) 2 ) and the triblock copolymer EO 20 PO 70 EO 20 (P123) at room temperature through the slow release of S 2 - ions from thioacetamide (TAA). X-ray powder diffraction (XRD),…
The effect of CF4 gaseous plasma exposure to single-wall carbon nanotubes (CNTs) has been studied. Raman spectroscopy results show that CNTs have gained more disordered sp3 bonds associated with functionalization, as both the flow rates of gas in the plasma and exposure time in the plasma are increased. Scanning elect…
Microstructure evolution of ceria-based mixed oxides CeO 2 −MO 2 (M = Si 4+, Ti 4+, and Zr 4+ ) after thermal treatments in the temperature range of 773−1073 K were investigated by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and other techniques. The CeO 2 −SiO 2 was synthesize…
The concept of the perfect lens introduced by Pendry [Phys. Rev. Lett. 85, 3966 (2000)], i.e., a possibility to achieve optical resolution well below the wavelength limit using a backward wave (also called Veselago or double-negative) material slab lens, is reinvestigated. It is shown that there is a direct analogy be…
Epitaxial (001)-, (118)-, and (104)-oriented Nd-doped Bi4Ti3O12 films have been grown by pulsed-laser deposition from a Bi4−xNdxTi3O12 (x=0.85) target on SrRuO3 coated single-crystal (100)-, (110)-, and (111)-oriented SrTiO3 substrates, respectively. X-ray diffraction illustrated a unique epitaxial relationship betwee…
Stability of anatase phase component present in commercial grade nanocrystalline powder of TiO2, synthesized from gas phase, is studied. Powders are heated at elevated temperatures under ambient conditions. X-ray and electron diffractometric studies are done to measure the microstructural parameters like crystallite s…
Structural transitions and the melting behavior of crystalline poly(ethylene oxide),(CH2-CH2-O)n, (PEO) has been investigated using fully atomistic, constant pressure-constant temperature (NPT) molecular dynamics (MD) simulations. Melting of PEO proceeds in two stages; Order parameters reveal the loss of interchain or…
Decreasing the oxide thickness in carbon nanotube field-effect transistors (CNFETs) improves the turn-on behavior. However, we demonstrate that this also requires scaling the range of the drain voltage. This scaling is needed to avoid an exponential increase in off-current with drain voltage, due to modulation of the…
The chromism of tungsten oxides has been investigated for a long time because of its academic and application importance. In this article the photochromism and its dynamics for a WO 3 aqueous sol and WO 3 −TiO 2 mixed sols are studied in detail. The chromic performance of the WO 3 aqueous sol is improved significantly…
Near-stoichiometric Bi1.5Zn1.0Nb1.5O7 (BZN) films were deposited by rf magnetron sputtering. The relative permittivity and dielectric loss of BZN films were measured with frequencies up to 100 MHz using planar Al2O3/Pt/BZN/Pt and Si/SiO2/Pt/BZN/Pt capacitor structures. BZN films with thicknesses in the range of 160 to…
Quantum Monte Carlo (QMC) and density-matrix renormalization group (DMRG) methods are used to study the coupled spin-pseudospin Hamiltonian in one-dimension (1D) that models the charge-ordering instability of the anisotropic Hubbard ladder at quarter filling. We calculate the temperature dependence of the uniform spin…
Using surface-enhanced Raman scattering (SERS) and Fourier transform infrared (FTIR) spectroscopy, we show that composites based on polyaniline (PANI) and single-walled carbon nanotubes (SWNTs) are different when they are prepared by two different methods: (1) by adding dispersed SWNTs to the polymer solutions and (2)…
Aggregates of the diacid form of tetrakis(4-sulfonatophenyl)porphine (TPPS), formed in acidic aqueous solutions, were deposited onto hydrophilic (mica) and hydrophobic (polystyrene and graphite) substrates and imaged using atomic force microscopy (AFM). The AFM images revealed the aggregates were either individual rod…
The bactericidal activity of copper-deposited titanium dioxide thin film (Cu/TiO2) was investigated under very weak ultraviolet (UV) light illumination. To elucidate the roles of the film photocatalyst and the deposited copper in the bactericidal activity, cells from a copper-resistant Escherichia coli (E. coli) strai…
We consider phononic heat transport through molecular chains connecting two thermal reservoirs. For relatively short molecules at normal temperatures we find, using classical stochastic simulations, that heat conduction is dominated by the harmonic part of the molecular force-field. We develop a general theory for the…