Materials Literature
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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…
We present a nonperturbative solution of the rotational diffusion equation for an asymmetric rotor reorienting in a uniaxial liquid crystal, such as a nematic, smectic A or membrane bilayer covering the full range of order parameters from isotropic to complete order for rod-like and plate-like molecules. We obtain exp…
The structural properties of neutral iron clusters ${\mathrm{Fe}}_{\mathit{n}}$ (n\ensuremath{\le}4) are investigated using a first-principles, all-electron, linear-combination-of-Gaussian-orbitals method. The ground states are all ferromagnetic with highest-dimensional geometry. They exhibit a tendency toward enhance…
Three diphenyl-diacetylene nematic liquid-crystal homologs were synthesized and two mixtures formulated. Dielectric constant, threshold voltage, splay elastic constant, birefringence, order parameter, and rotational viscosity of these liquid crystals were evaluated at elevated temperatures. These highly conjugated liq…
We have studied the thermal conductivity and thermoelectric power of single crystals of titanium carbide (${\mathrm{TiC}}_{\mathit{x}}$). This material crystallizes in the sodium chloride structure for a range of stoichiometries. We have investigated samples with x=0.88, 0.93, and 0.95. The thermal conductivity contai…
The validity of Kondorsky’s switching field distribution for pinning magnets with rectangular hysteresis loops is extended to cases where the hysteresis loops are influenced by reversible rotation of the magnetization vectors in the domains. Caused by this influence, the monotonic Kondorsky function changes to modifie…
The influence of disorder on shear viscosity of undercooled melts is described by the formula η=η0⋅exp(θ/T )a. It is shown that this expression reproduces the existing experimental data with a reasonable accuracy for a broad range of substances of various nature (silicates, borates, germanates, phosphates, Se, glucose…
Specular and nonspecular absolute x-ray-reflectivity measurements have been performed on the Au(001) surface between T=300 and 1250 K. At all temperatures the surface-normal vibrational amplitudes are increased above the corresponding bulk thermal vibrational amplitude (Debye-Waller factor). Below T=1170 K, the surfac…
We study transitions to periodic structures in block copolymers melts, including concentration fluctuations self-consistently in the analysis. Phase diagrams are constructed for diblock and triblock copolymers of finite molecular weight. The concentration fluctuations increase the stability of the isotropic state, and…
If a surface-modulated diffraction grating is arranged so that the scattering vector does not lie in the plane of incidence of the illuminating radiation, then polarization conversion can occur. This conversion can be strongly enhanced if a surface mode, such as a surface-plasmon-polariton or guided mode, is excited a…