Materials Literature
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We investigate the electronic structure of gap and band tail states in amorphous silicon. Starting with two 216-atom models of amorphous silicon with defect concentration close to the experiments, we systematically study the dependence of electron localization on basis set, density functional and spin polarization usi…
Single-walled carbon nanotubes (SWNTs) have many interesting properties; they may be metallic or semiconducting depending on their diameter and helicity of the graphene sheet. Hydrostatic or quasi-hydrostatic high pressures can probe many electronic features. Resistance - temperature measurements in SWNTs from normal…
A recent theory for stress transmission in isostatic granular and cellular systems predicts a constitutive equation that couples the stress field to the local microstructure. The theory could not be applied to macroscopic systems because the constitutive equation becomes trivial upon straightforward coarse-graining. T…
Spectra of parametric X-ray radiation (PXR) are considered in the range of anomalous dispersion for one of the atoms in a crystal elementary cell. The PXR spectra are calculated both for the ultra-relativistic and non-relativistic electrons for the specific conditions corresponding to the organic compounds . It is sho…
We present a comparison between accurate \textit{ab initio} calculations and a high-quality experimental data set (1986-2002) of electric-field gradients and magnetic hyperfine fields of Cd at different sites on Ni, Cu, Pd and Ag surfaces. Experiments found a systematic rule to assign surface sites on (100) and (111)…
Two types of polyelectrolyte multilayer films have been reported in the literature. These are (i) films whose mass and thickness increase linearly as the number of deposited bilayers increases and (ii) films that grow exponentially. We present a model for the buildup of exponentially growing films that allows a discus…
The state of the chromium ions on Cr/ZrO 2 and Cr/TiO 2 samples has been tested by the IR spectra of adsorbed CO and NO. CO adsorption on activated samples leads mainly to formation of carbonyls related to the support. At low temperature, CO is also bonded to Cr n + −OH groups that are present in low concentration. Wh…
The gain spectra in Er3+ doped and Er3+/Ce3+ codoped tellurite glass fibres have been compared at 980 nm pump wavelength. The observed gain at 1.53 µm increased from 16 to 31 dB in a 12 cm long Er3+/Ce3+ codoped fibre, and the gain changed less than 2 dB with a 20 dB variation in signal power.
Abstract Following our continued interest in the production of bioerodible and biodegradable functional polymers for biomedical applications, we synthesized and characterized new unsaturated polyesters. The presence of functional groups in the polymer backbone provided sites for chemical modification, and through a va…
This letter reports a Pb(Zr0.5Ti0.5)O3 (PZT) based composition, which provides high piezoelectric and electromechanical properties. The general form of the composition is Pb(Zn1/3Nb2/3)x(B1/3I′B2/3II′)y(Zr0.5Ti0.5)1−x−yO3+0.5 wt % MnO2 (x+y=0.2). Four compositions corresponding to the earlier formulation were studied.…
Amorphous Si−C−N ceramics were produced over a wide range of compositions by thermolysis of structurally different polysilazanes. The structure of the as-thermolyzed amorphous ceramics and of ceramic samples after additional heat treatments was investigated by diffraction experiments in the wide-angle and the small-an…
Single-crystalline all-perovskite SrRuO3/Ba0.7Sr0.3TiO3/SrRuO3 thin-film capacitors epitaxially grown on SrTiO3 exhibit a sharp paraelectric-to-ferroelectric phase transition at 350 K with a maximum permittivity of about 6660. This value is comparable to that of bulk ceramics and exceeds by several times the highest v…
Recent advances in the fabrication and characterization of semiconductor and metallic nanowires are proving very successful in meeting the high expectations of nanotechnologists. Although diamond has been found to possess remarkable electronic and chemical properties, development of diamond nanowires has been slow. Su…
A time-dependent Ginzburg-Landau model of plastic deformation in two-dimensional solids is presented. The fundamental dynamic variables are the displacement field u and the lattice velocity v=delta(u)/delta(t). Damping is assumed to arise from the shear viscosity in the momentum equation. The elastic energy density is…
CdS nanoparticles are incorporated into a poly(acrylic acid) (PAA) film associated with an Au electrode, and the nanoparticles are covalently linked to the matrix. Cu 2+ ions are incorporated into the CdS-nanoparticle−PAA film, and the electroswitchable photocurrent generation by the system, in the presence of trietha…
Thermoluminescence of undoped and doped CaB 4 O 7 with activators such as Cu and Mn has been investigated. The polycrystalline samples of undoped and doped CaB 4 O 7 are prepared by melting method. The formation of CaB 4 O 7 compound is checked by X-ray diffraction study and the compound is found to have orthorhombic…
Abstract Poly(vinyl pyrrolidone‐ co ‐isobutyl styryl polyhedral oligomeric silsesquioxane)s (PVP–POSS) were synthesized by one‐step polymerization and characterized using FTIR, high‐resolution 1 H‐NMR, solid‐state 13 C‐NMR, 29 Si‐NMR, GPC, and DSC. The POSS content can be controlled by varying the POSS feed ratio. The…
We have studied the simultaneous effects of magnetic and electric fields on the ground-state energy of a donor impurity confined in a polar CdSe quantum nanocrystallite embedded in a nonpolar matrix. Calculations are performed in the framework of the effective-mass approximation using the Hass\'e variational approach.…
Poly(3-dodecyl thiophene) (P3DDT) produces thermoreversible gels in o -, m -, and p -xylene (Xy). All of these gels have fibrillar network morphology and exhibit reversible first-order phase transitions. The enthalpy changes related to the polymer part of P3DDT− p -Xy gels indicate polymer−solvent complex formation ha…
An exploration of the manganese oxalate-phosphoric acid-water system under hydrothermal conditions, and using "reagent" quantities only of water, has led to the isolation of a new mixed anion framework material Mn(2)(H(2)PO(4))(2)(C(2)O(4)). This material features continuous chains of cis edge-sharing MnO(6) octahedra…