Materials Literature
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The effect of low levels of poly(o-methoxyaniline) (POMA) on the crystallization, morphology, and electrical characteristics of blends with poly(vinylidene fluoride) (PVDF) were studied by infrared spectroscopy, AC electrical measurements, and optical microscopy. Undoped POMA has a strong effect in increasing the α-ph…
We extend the symmetrized density-matrix renormalization-group method to compute the dynamic nonlinear optical coefficients for long chains. By computing correction vectors in the appropriate symmetry subspace, we obtain the dynamic polarizabilities, ${\ensuremath{\alpha}}_{\mathrm{ij}}(\ensuremath{\omega})$, and thir…
The title compound, tetracalcium dialuminum dodecahydroxide dinitrate tetrahydrate, of composition 3CaO.Al 2 O 3 .Ca(NO 3 ) 2 .10H 2 O, is a layered compound constituted by positively charged [Ca 4 Al 2 (OH) 12 ] 2+ main layers and negatively charged [2NO 3 .4H 2 O] 2- interlayers. It crystallizes in the trigonal P3c1…
We calculate the optical constants of porous silicon (por-Si) from the electronic band structure obtained by means of an ${\mathrm{sp}}^{3}{s}^{*}$ tight-binding Hamiltonian and a supercell model, in which the pores are columns dug in crystalline Si. The position of the absorption edge of the material is defined by tw…
The conduction-band structure of single crystals ${\mathrm{Bi}}_{2\ensuremath{-}x}{\mathrm{Sb}}_{x}{\mathrm{Se}}_{3}$ $(0<~x<~0.52)$ was investigated in high magnetic fields by the Shubnikov--de Haas (SdH) effect (up to 40 T) and cyclotron resonance (up to 150 T). Signals from two conduction bands were detected…
The melt spinning of nylon 6 has been studied with on-line wide-angle synchrotron X-ray scattering techniques. The apparatus consisted of a single screw extruder and a metering pump mounted on a horizontal platform that could be translated in the vertical direction allowing a range of distances to be sampled with the…
The effects of different types of boundaries on graphite fragments are considered as they influence the π-electrons. From a simple resonance theoretic argument there are proposed simple structural conditions governing the occurrence of “unpaired” π-electron density near the edges. Predictions based on these rules are…
The finite–element (FE) method is commonly used to solve boundary value problems in continua. Constitutive equations based on crystal plasticity have been implemented in FE simulations, and these slip–based calculations have the potential to model a variety of interesting phenomena. However, the substructure of the de…
The magneto-optic (MO) Kerr and Faraday spectra for manganese pnictides are calculated using the all electron, relativistic, full-potential linear muffin-tin orbital method. The amplitude of our calculated spectra are found to be in good agreement with corresponding experimental spectra. Although the MO property is a…
We have studied the electronic structure of a class of half-Heusler compounds $M\mathrm{NiPn},$ where M is Y, La, Lu, Yb, and Pn is a pnicogen As, Sb, Bi. All these systems excepting Yb are narrow-gap semiconductors and are potential candidates for high-performance thermoelectric materials. The Yb system shows heavy f…
Current-voltage $(I\ensuremath{-}V)$ behaviors of ${\mathrm{P}\mathrm{b}(\mathrm{Z}\mathrm{r},\mathrm{}\mathrm{T}\mathrm{i})\mathrm{O}}_{3}$-based capacitors with ${(\mathrm{L}\mathrm{a},\mathrm{}\mathrm{S}\mathrm{r})\mathrm{C}\mathrm{o}\mathrm{O}}_{3}$ electrodes were studied to investigate the dominant leakage mecha…
Highly ordered MCM-41 silicas were synthesized in the presence of alkyltrimethylammonium surfactants and characterized using powder X-ray diffraction and nitrogen adsorption at 77 K. Samples prepared in the presence of hexadecyltrimethylammonium (HTMA + ) and octadecyltrimethylammonium surfactants using the repeated p…
Using a femtosecond pump-probe technique, the fundamental mechanical radial mode of silver nanoparticles is coherently excited and probed via its interaction with the electron gas. The mechanical oscillations are launched by an indirect displacive process and are detected via the induced modulation of the surface plas…
The surface valence transition was observed in the insulating rare-earth compounds which are integral valent in the bulk. From the careful study of Eu $3d,$ Eu $4d$, and Eu $4f$ core-level photoelectron spectra of ${\mathrm{EuF}}_{3},$ ${\mathrm{Eu}}_{2}{\mathrm{O}}_{3},$ and ${\mathrm{EuCl}}_{3},$ we unambiguously id…
We study in detail by means of ab-initio pseudopotential calculations the electronic structure of five-fold coordinated (T_5) defects in a-Si and a-Si:H, also during their formation and their evolution upon hydrogenation. The atom-projected densities of states (DOS) and an accurate analysis of the valence charge distr…
We present a NMR pulse double-irradiation method which allows one to separate magnetic from quadrupolar contributions in the spin-lattice relaxation. The pulse sequence fully saturates one transition while another is observed. In the presence of a Delta m = 2 quadrupolar contribution, the intensity of the observed lin…
The analytical properties of macroscopic transport coefficients of two-component composites are first used to discuss the thermoelectric power factor of such a composite. It is found that the macroscopic power factor can sometimes be greater than the power factors of both of the pure components, with the greatest enha…
Deposition of tin-doped–indium-oxide (ITO) on unheated substrates via low energy processes such as electron-beam deposition can result in the formation of amorphous films. The amorphous-to-crystalline transformation was studied in this system using in situ resistivity, time resolved reflectivity, glancing incidence an…
This article presents an analysis of the response of boron carbide (B4C) to severe loading conditions that produce large strains, high strain rates, and high pressures. Experimental data from the literature are used to determine and/or estimate constants for the JH-2 constitutive model for brittle materials. Because B…
The evolution in microstructure and local crystallography is described, with emphasis on the behaviour of medium to high stacking fault energy FCC metals deformed at low temperature. This evolution is analysed within a common framework of grain subdivision on different size scales. The largest scale is the macroscopic…