Materials Literature
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To improve the stability of porous Si (PS) prepared by electrochemical etching, we make use of rapid-thermal oxidation (RTO). During RTO processing, the hydride coverage of the internal surfaces of the pores is replaced by a high-quality oxide while retaining nm-sized Si grains. With increasing process temperature Tox…
A simple density functional theory (DFT) is applied to an analysis of the isotropic, nematic and smectic-A phase transitions in single component systems comprised of hard convex bodies. In the chosen DFT, the exact orientation dependent second virial coefficient is used together with an approximation due to Parsons wh…
Abstract The intramolecular (internal) charge sensitivity analysis ( ICSA ) is presented in the molecular orbital ( MO ) resolution, with diagonal idempotency constraints being imposed on the MO occupations, n , which can then be considered as independent electron population variables of the system for the assumed fix…
Tire de :'AIAA 4th International Aerospace Planes Conference', Orlando, FL (USA), December 1-4, 1992
It is shown theoretically that the quadrupole relaxation probabilities W 1 and W 2 of 23 Na in the ferroelectric material NaNO 2 , caused by random 180 degrees reorientations of the NO 2 groups associated with the order-disorder transition, should be proportional to (1-S 2 )(1-S)exp( Delta U/kT), where S is the order…
The low-frequency (below the loss peak, or critical frequency, omega c ) conductivity, sigma ( omega ), of the Fermi glass is evaluated in an approximation replacing cluster currents with chain currents. Long chains with relatively low resistance values but large relaxation times make an important contribution to the…
Spectral blue shift of excitonic transition due to quantum confinement in Si0.84Ge0.16/Si strained-layer quantum wells, grown by gas-source Si molecular beam epitaxy, is reported. Intense photoluminescence was observed at elevated temperatures though reduced in intensity due to the thermalization of holes to the Si ba…
For the first time, epitaxial barium-ferrite thin films, predominantly of the magnetoplumbite structure, with an easy axis of magnetization in-plane have been prepared on single-crystal sapphire substrates by reactive sputtering and post-deposition annealing. Lattice images by high resolution transmission electron mic…
Abstract Glycogen phosphorylase catalyses the reversible phosphorylation of glycogen to give glucose-1-phosphate in a reaction mechanism promoted by the 5'-phosphate of the cofactor pyridoxal phosphate. The reaction with the small substrate heptenitol has been probed using Laue diffraction at the Synchrotron Radiation…
Pentastrontium chloride trisorthoborate, Sr[sub 5](BO[sub 3])[sub 3]Cl, M[sub r] = 649.98, orthorhombic, C222[sub 1], a = 10.000(2), b = 14.202(2), c = 7.421(1) A, V = 1053.9 A[sup 3], Z = 4, D[sub x] = 4.096 mg m[sup -3], [lambda](MO K[alpha]) = 0.71069 A, [mu] = 24.7 mm[sup -1], F(000) = 1176, T = 295 K, R = 0.045 f…
The optical properties of WO3 polycrystalline thin films prepared by oxidation of ‘‘reflective’’ tungsten films in three different conditions of temperature and ambient have been studied by standard reflection-transmission measurements. The resulting dispersion parameters E0 and Ed [S. H. Wemple and M. DiDomenico, Phy…
The isothermal elastic constants for the face-centered-cubic (fcc) and body-centered-cubic (bcc) hard-sphere crystal are calculated for a range of densities using the modified weighted-density functional of Denton and Ashcroft [Phys. Rev. A 39, 4701 (1989)]. The fcc elastic constants are shown to be in excellent agree…
The exact solution of the Peierls-Fr\"ohlich problem on a self-consistent state of conduction electrons and a chain deformation near zero temperature is obtained in the continuum approximation. The charge-density-wave (CDW) state in various relations between parameters of the problem (electron density, electron-phonon…
The transverse electro-optic effect in antiferroelectric lead zirconate thin films grown on fused quartz is observed. The birefringence shift as a function of the external electric field exhibits a characteristic response that is related to the electric-field-induced antiferroelectric-to-ferroelectric structural trans…
Shallow impurities in n-type indium selenide (InSe) have been investigated by means of Fourier-transform spectroscopy in the far-infrared region. Three electric dipole transitions have been identified: 1s-2${\mathit{p}}_{\ifmmode\pm\else\textpm\fi{}}$, 1s-2${\mathit{p}}_{0}$, and 1s-3${\mathit{p}}_{\ifmmode\pm\else\te…
The static and dynamic second hyperpolarizability tensors of oligomers of polyacetylene, polyparaphenylene vinylene, and polythienylene vinylene are evaluated by means of the valence effective Hamiltonian (VEH) method. The sum-over-states (SOS) approach is exploited, by constructing excited states from both single- an…
Abstract Superabsorbent polymers based on guargum have been prepared through a graft‐copolymerization reaction using acrylonitrile as the monomer by a gamma ray‐induced irradiation technique. Various grafting parameters have been studied. The grafted products have been characterized using infrared spectroscopy, thermo…
We have studied the size-dependent optical properties of confined excitons in chainlike Si-backbone polymers with 5--110 Si atoms. The blueshift of the lowest exciton state was observed with decreasing number of Si atoms. In chains having 20 Si atoms or less, the oscillator strength per Si atom for the lowest exciton…
Cristallisation dans P4 2 /mnm avec a=7.596, c=8.027A, Z=2; affinement jusqu'a R=0.039. L'ion Cu 2+ est dans une coordination octaedrique deformee constituee de deux ions Cl a 3.000A, deux ions Cl a 2.257A et deux molecules d'eau a 1.969A aux positions equatoriales du plan carre. Chaque molecule d'eau est coordinee de…
Abstract We measured the thermal conductivity of a polyethylene/polystyrene blend containing SEBS block copolymer, which has two components of polystyrene block and hydrogenated polybutadiene block, and discussed the effect of phase inversion on the thermal conductivity by observing the morphorogy of the blend. Furthe…