Materials Literature
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Various polygonal defects which retain the three-bonded character of carbon are proposed as disclinations in graphitic carbon. The n-gonal defects, where n is an integer less than 5, are responsible for forming cones and are less stable than pentagonal defects in a hexagonal network which are responsible for forming s…
The oxygen adsorption on the Zr(0001) surface is studied using first-principles total-energy and force calculations. We calculated the atomic structure, heat of adsorption, work function, and electronic structure for oxygen occupying various surface and subsurface sites for both the Zr(0001)-(1\ifmmode\times\else\text…
Electrical and optical properties of electroluminescent porous silicon pn diodes have been investigated. The measurements were performed under pulsed conditions to maintain high quantum efficiency (∼0.2%) operation. Diodes with different peak wavelengths, obtained by varying the etching parameters, were used. A high c…
Glass transition in the system poly(methyl methacrylate)/compressed gas was studied as a function of the gas pressure p using a high-pressure Tian-Calvet heat flow calorimeter. Measurements were made on PMMA-CH4-C2H4, and ;-CO2 at pressures to 200 atm. All three gases plasticize the polymer leading to depression of th…
The properties of 100-nm-thick reactively sputter-deposited TiN films with different deposition conditions and one chemical-vapor-deposited film have been studied as diffusion barriers between Cu and Si by using sheet resistance measurements, x-ray diffractometry, etch-pit test, and Auger electron spectroscopy (AES).…
Amorphous hydrogenated carbon films have been deposited on crystalline silicon and on glass from an expanding thermal plasma. Two deposition parameters have been varied: the electric current through the plasma source and the admixed acetylene flow. No energetic ion bombardment has been applied during deposition. Ex si…
Quantitative x-ray-diffraction measurements were performed on a nanocrystalline Cu sample made by severe plastic deformation. The shape of Bragg reflections was found to be represented primarily by a Lorentzian function. A difference of as much as 6%±3% was revealed between the integrated intensities from the nanocrys…
The high- and low-pressure phases of crystalline boron oxide ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$ are investigated by first-principle calculations using a local-density approximation (LDA). Both phases are insulators with wide LDA band gaps of 6.20 eV for ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$-I (low pressure) and 8.85-…
We present a model of size-dependent luminescence from a-Si:H and show that a blueshift of the luminescence energy and a general increase in luminescence quantum efficiency are predicted as structure size decreases. In contrast to bulk a-Si:H structures, highly confined a-Si:H exhibits visible luminescence peak energi…
N-layer superlattices are formed out of a periodic repetition of N different slabs. Such materials for N=3 and 4 are now easily grown by molecular-beam epitaxy. We present closed form expressions for localized and resonant transverse elastic waves associated with the surface of a semi-infinite N-layer superlattice, wi…
A binary system of parallel hard spherocylinders and hard spheres are considered to examine influence of addition of spherical molecules to the pure system of rod-like molecules, especially the influence on the structure of the smectic-A phase. Free energy of the system is calculated through the second virial approxim…
Magnetic Fe3C and α-Fe ultrafine particles were prepared by laser-induced pyrolysis of Fe(CO)5 and C2H4. It is found that after passivation, the Fe3C particles exhibit a high saturation magnetization of 132 emu/g compared to that of the α-Fe particle, 95 emu/g. By determining the oxygen content and the present states…
An iterative algorithm is developed for calculating nonlinear optical polarizabilities using a series of generalized sum rules that resemble the Lanczos algorithm and connect spectral moments of the driven single-electron density matrix to ground state charge distributions and bonding network. The size scaling and sat…
Theoretical calculations in combination with experiments for the ${\mathrm{\ensuremath{\pi}}}^{\mathrm{*}}$ and ${\mathrm{\ensuremath{\sigma}}}^{\mathrm{*}}$ x-ray absorption edges are reported for graphite. Theory and experiment agree well for the leading ${\mathrm{\ensuremath{\pi}}}^{\mathrm{*}}$ and ${\mathrm{\ensu…
The excess free energy of small molecules in the amorphous polymers poly(ethylene) and poly(dimethylsiloxane) was calculated, using the test-particle-insertion method. The method was applied to polymer configurations obtained from molecular dynamics simulations with differently prepared initial guess configurations. I…
We report the presence of charge-density waves (CDW's) in the planar square lattices of the layered compounds ${\mathrm{LaTe}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sb}}_{\mathit{x}}$ for 0\ensuremath{\leqslant}x\ensuremath{\leqslant}1, which we have studied through electron microprobe analysis, powder- and s…
We present results of a Monte Carlo simulation of a dense blend, comprising two incompatible homopolymers and a symmetric diblock copolymer, all of the same degree of polymerization. The simulations, in the framework of the bond fluctuation model, yield information on the phase diagram. At high temperatures the copoly…
The spectral behavior and the temperature dependence of the absorption coefficient of microporous silicon films are studied in the energy range of 1.2–3.8 eV, between 7 and 450 K. For photon energies above the direct band gap at 3.3 eV, the spectral behavior of the absorption coefficient is similar to that of crystall…
We studied the size dependence of the ferroelectric domain structure in unique free-standing ${\mathrm{PbTiO}}_{3}$ thin film, composed of grains 60--1000 nm in size, with transmission-electron microscopy. With such samples, we showed that the apparent dependence of electrical properties on the thickness of polycrysta…
Optical spectra of a single crystal of ${\mathrm{La}}_{1.67}$${\mathrm{Sr}}_{0.33}$${\mathrm{NiO}}_{4}$, which undergoes a charge-ordering transition at ${\mathit{T}}_{\mathrm{CO}}$\ensuremath{\sim}240 K, have been investigated for wide ranges of photon energy (0.008--3 eV) and temperature (10--480 K). The opening of…