Materials Literature
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Self-fracturing of solids during chemical transformations is considered, and a first quantitative model of this widespread phenomenon is proposed. The analysis begins by considering the equilibrium of a single crack, and proceeds with the behavior of an ensemble of cracks. This enables one to solve the ``selection pro…
The drag force (per unit length) acting on a steadily moving disclination line is calculated. The problem is formulated in two equivalent ways: One involving a linear partial differential equation but with ambiguous boundary conditions, and another involving a nonlinear equation but with uniquely defined boundary cond…
We have investigated both the structures and the excitation spectra produced by submonolayer adsorption of potassium on the surface of graphite at 90 K, using high-resolution low-energy electron diffraction in conjunction with high-resolution electron-energy-loss spectroscopy. We show that at very low coverages a disp…
Molecular beam mass spectrometry has been used to determine the concentrations of several free-radical and stable gaseous species in a hot-filament reactor under diamond-growth conditions. At a filament temperature of 2600 K, the H-atom concentration in the proximity of the growth surface was found to decrease with in…
We have measured the Compton-scattering cross section on hydrogen at 60\ifmmode^\circ\else\textdegree\fi{} and 135\ifmmode^\circ\else\textdegree\fi{} using monochromatic tagged photons spanning the energy between 32 and 72 MeV. These data, when analyzed with a low-energy expansion of the scattering cross-section formu…
Nonergodicity parameters, the nondecaying components of the coherent intermediate scattering functions, of ``hard-sphere'' colloidal glasses were measured by dynamic light scattering. These agree reasonably well with the predictions of mode-coupling theory for hard-sphere atoms, with no adjustable parameters in the co…
The electronic structure of the formally ${\mathrm{Cu}}^{3+}$ (${\mathit{d}}^{8}$) compound ${\mathrm{NaCuO}}_{2}$ has been studied by photoemission spectroscopy and subsequent cluster configuration-interaction calculations. We find that the ${\mathit{d}}^{8}$\ensuremath{\rightarrow}${\mathit{d}}^{9}$L (L: ligand hole…
Silicon ${\mathit{L}}_{2,3}$ absorption spectra are obtained by spatially resolved electron-energy-loss spectroscopy as a function of distance away from the buried Al/Si(111) interface. Within 0.6 nm, scattering below the bulk absorption threshold is observed, accompanied by changes in shape above the threshold. In si…
The cooperative motion algorithm is applied to simulate static properties of a polymer melt confined between two parallel walls, where the melt consists of linear chains which are grafted by one end to one wall. The results characterizing the structure of layers, as well as the conformation and orientation of chains,…
The symmetry arguments of Appelbaum, Baraff, and Hamann for integrals of physical quantities for the (110) and (100) surface orientations of zinc-blende-structure crystals are generalized for other crystals and surface orientations of lower symmetry. We define the surface region by identifying boundaries in the interi…
Boron nitride films prepared by reactive ion plating from a boron evaporation source were characterized structurally using three independent electron optical techniques: energy filtered electron diffraction with radial distribution function analysis; electron energy-loss spectroscopy of the near-edge structure of the…
Monte Carlo simulation data from the two-dimensional facilitated kinetic Ising model proposed by Fredrickson and Andersen is examined with the goal of understanding the processes responsible for the characteristic features of glassy dynamics. The spatial distribution of spin flip rates is found to be highly nonuniform…
Best-case evaluations are made for potential optoelectronic applications of erbium-doped silicon (EDS). The objective is to find the upper limit of performance when EDS is used as light-emitting diodes, amplifiers/modulators, and lasers. Every effort is made to use intrinsic parameters whose values are determined by p…
We consider coarsening processes of precipitates in open systems where homogeneous cells are coupled together by the diffusion of the solute. Using dynamical scaling assumptions and performing numerical simulations on a two-cell model, we have obtained the following results: First, the supersaturation in each cell asy…
The photoelectron spectra of U-Ge compounds, UGe 2 , U 3 Ge 4 and U 5 Ge 3 , have been measured at room temperature for excitation photon energies from 32 to 120 eV using synchrotron radiation. The spectral distributions of the state density of the U 5 f electron and those of electrons in the states other than the U 5…
Aniline has been intercalated in lead iodide thin films by exposure to aniline vapors in an evacuated chamber. X-ray diffraction and Raman spectroscopy have confirmed the presence of aniline in the interlayer space of ${\mathrm{PbI}}_{2}$. Intercalation leads to an increase of 0.5 eV in the optical band gap. The large…
Interdiffusion in the Cu-based Cu/Pd, Cu/Pt, Cu/Ni, Cu/NiB, Cu/Co, Cu/Cr, Cu/Ti, and Cu/TiN bilayer films has been investigated for anneal temperatures ranging from 150 to 400 °C in forming gas (N2-10%H2). The diffusion of Pd, Pt, and Ni into Cu has resulted in a significant increase in the sheet resistance of the fil…
The photoluminescent quantum efficiencies of the inorganic phosphors Y2O2S:Eu, Y2O3:Eu, La2O2S:Tm, Gd2O2S:Tb, and Sr5Cl(PO4)3:Eu have been measured in the range 17 to 450 eV. The optical properties of these phosphors from 2 to 160 eV have been determined from inelastic electron scattering measurements. Using a model w…
A measure of cooperativity in glassy liquids is defined in terms of the kinetic correlation length of relaxation at a surface. This length and its temperature dependence is measured for the facilitated kinetic Ising model with both free and pinned surfaces. A simple power law is found to describe the relationship betw…
The orientational ordering of four 4-n-alkyl-4′-cyanobiphenyls (kCB’s: 5CB, 6CB, 7CB, 8CB) and four 4-n-alkoxy-4′-cyanobiphenyls (kOCB’s: 5OCB, 6OCB, 7OCB, 8OCB) in their nematic phase was studied at different temperatures by C-13 NMR. The technique used was a combination of variable-angle spinning and a two-dimension…