Materials Literature
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We investigate the electron-hole interactions in spherical silicon nanocrystals by incorporating Coulomb, exchange, and spin-orbit couplings into a tight-binding model. We study the effect of the electron-hole attraction on the absorption spectra and on the dielectric constant, using a real-time propagation technique.…
The relative chemical stability of two commercially available polyurethanes-Pellethane, currently used in biomedical devices, and Corethane, considered as a potential biomaterial-was investigated following aging protocols in hydrolytic and oxidative conditions (HOC, water, hydrogen peroxide, and nitric acid) and in ph…
The structural and electronic properties of ${\mathrm{Cu}}_{2}\mathrm{O}$ have been investigated using the periodic Hartree-Fock method and a posteriori density-functional corrections. The lattice parameter, bulk modulus, and elastic constants have been calculated. The electronic structure of and bonding in ${\mathrm{…
Bond rotation defects close the gap in large-gap nanotubes, open the gap in small-gap nanotubes, and increase the density of states in metallic nanotubes. Not only are these defects likely to be present in as-grown nanotubes, but they could be introduced locally into intact nanotubes, thereby opening a new road toward…
The molecular dynamics in the glass transition of the ``quasi''--van der Waals glass salol confined to nanopores (2.5, 5.0, and 7.5 nm) with lubricated inner surfaces is found to be faster (by up to 2 orders of magnitude) than in the bulk liquid. This effect of confinement is more pronounced for smaller pores. It refl…
Bound magnetic polarons (BMP's) in $p$-type ${\mathrm{Cu}}_{2}{\mathrm{Mn}}_{0.9}{\mathrm{Zn}}_{0.1}{\mathrm{SnS}}_{4}$ were investigated using magnetization measurements. The magnetization $M$ was studied from 2 to 60 K in magnetic fields up to 55 kOe. The data show the characteristic features of BMP's in the collect…
Conducting polymers that can be switched between a neutral state and a doped state are of interest for charge storage applications. We report on the fabrication of an all-polymer charge storage device incorporating derivatized polythiophene films electropolymerized onto graphite-coated polymeric supports and a polymer…
Calculations have been performed using the generalized-gradient approximation (GGA) for the exchange-correlation functional of Perdew, Burke, and Ernzerhof (PBE) within density-functional theory for atoms, clusters, and crystals, including crystalline C, Al, Si, and GaAs. The calculations of the atomic total energy an…
The reflectance of single crystal LaSrGaO4 has been measured from approx 50 to 40000 cm^-1 along the "a" and "c" axis. The optical properties have been calculated from a Kramers-Kronig analysis of the reflectance for both polarizations. The reflectance curves have been fit using a product of Lorentzian oscillators.
Silicon clusters and nanocrystals have been generated by CO${}_{2}$-laser-induced decomposition of SiH${}_{4}$ in a flow reactor. By introducing a conical nozzle into the reaction zone, the clusters are extracted into a molecular-beam machine and analyzed with a time-of-flight mass spectrometer (TOFMS). Since the clus…
A broad absorption band around 500 nm is observed in ZnS nanoparticles. The absorption becomes more intensive and shifts to the blue as the particle size is decreased. The absorption energy is lower than the band gap of the particles and is considered to be caused by the surface states. This assignment is supported by…
The complete sets of elastic constants of 4H and 6H silicon carbide single crystals were determined by Brillouin scattering. The elastic constants of 6H SiC are C11=501±4, C33=553±4, C44=163±4, C12=111±5, and C13=52±9 GPa; the corresponding ones of 4H SiC are the same within experimental uncertainties. The compressibi…
We report first-principles calculations of the structural, lattice-dynamical, and dielectric properties for zinc-blende and wurtzite BN and AlN. The ground-state properties, i.e., the lattice constants, the bulk moduli, the ionicity factors of the chemical bonds, and the elastic constants, are calculated using a plane…
We critically review dissipative particle dynamics (DPD) as a mesoscopic simulation method. We have established useful parameter ranges for simulations, and have made a link between these parameters and χ-parameters in Flory-Huggins-type models. This is possible because the equation of state of the DPD fluid is essent…
On the measurement of thermoelectric power and Nernst coefficient, we used two kinds of shapes for a sample. One is "Bridge shape" and the other is, we call,"Fat-Bridge shape". The latter has 5 times wider main body than the former. We used pure n-InSb in this experiment, whose carrier condensation measured at 77K was…
A phase diagram for the commercially significant ternary system poly(acrylonitrile-co-methylacrylate-co-sulfonic acid), sodium thiocyanate, and water, used to wet-spin textile acrylic fibers, was constructed from a linearized cloudpoint curve correlation. Experimental cloudpoints in the accessible low polymer content…
The effect of the addition of ethylenic copolymers with different acrylic acid contents on the morphology and coalescence of blends of thermoplastic polyurethane and polypropylene has been investigated. The blends were prepared using a twin-screw extruder. Although the copolymers were immiscible with both blend compon…
The known and usable truly nonlocal functionals for exchange-correlation energy of the inhomogeneous electron gas are the ADA (average density approximation) and the WDA (weighted density approximation). ADA, by design, yields the correct linear response function of the uniform electron gas. WDA is constructed so that…
The simultaneous effect of small deformation and short-range van der Waals attraction on the coalescence efficiency of two different-sized slowly sedimenting drops is considered. For spherical drops, it has been shown previously that the tangential mobility of drop surfaces makes collision possible even without van de…
We study the initiation of an unstable antiplane elastodynamic shear process under slip‐weakening friction. We give an analytical expression of the slip that we intrepret using an eigenvalue analysis. Considering only the part of the solution associated with positive eigenvalues, we define a “dominant part” characteri…