Materials Literature
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The electronic and structural properties of electrochemically synthetized five poly membered heterocycles [polypyrrole (PP), poly-N-methylpyrrole (PNMeP), polythiophene (PT), polybithiophene (PBT), and poly-3-methylthiophene (PMeT)] in their doped conducting and undoped semiconducting states have been determined by x-…
Monosilane pyrolysis has been studied by measuring the rate of silicon deposition from SiH4–Ar mixtures in a flow reactor at temperatures between 400–500 °C. By varying gas residence time, SiH4 partial pressure and total pressure, the process could be separated into experimental regimes dominated by either homogeneous…
Raman spectra of ${\mathrm{In}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As are observed over a wide range of composition. A GaAs-like mode frequency \ensuremath{\omega} is found to vary with the composition x as \ensuremath{\omega}=-32.4${x}^{2}$-18.6x+290.0 ${\mathrm{cm}}^{\mathrm{\ensuremath…
A molecular-dynamics method is applied in a study of silver diffusion in superionic conductor ${\mathrm{Ag}}_{2}$Te for several temperatures with use of effective pairwise potentials. The static and dynamical structures are calculated. The density distribution map of silver ions suggests that a Ag ion, located at a te…
The cyclotron mass m c and the Dingle temperature T D in the layered planes of the organic superconductors are determined by the Shubnikov-de Haas effect at ambient pressure; m c =0.4 m 0 and T D =7–8 K, for β-(BEDT-TTF) 2 IBr 2 ( T c =2 K), and (0.4–0.5) m 0 and 11 K for β-(BEDT-TTF) 2 I 3 (=1 K), and 3.5 m 0 and (0.…
Interaction of polyimide and two simple organic polymers with an evaporated chromium metal overlayer was studied by surface-sensitive carbon 1s near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The technique was used to measure unoccupied electronic states in the polymers. Assignments of C1s→π* transiti…
Stimulated by the recent numerical simulation results of Baumgartner and Muthukumar, an analytic derivation is given of the size of a polymer in random media. It is shown that, for long Gaussian chains in three dimensions, the mean square end-to-end distance 〈∼(R2)〉 is proportional to (uρ0)−2, where uρ0 is the measure…
SnO2 thin films having low resistivity were prepared by chemical vapor deposition. Conductivity, its dependence on temperature, and Hall effect of films were measured. Examination of the surface morphology by scanning electron microscope showed that the SnO2 thin films are made up of many grains. Experimental results…
We have carried out a complete, detailed study of magnetomechanical damping on a set of annealed and deformed iron specimens. The results for macroeddy-current and microeddy-current damping are consistent with previous data on iron. The macroeddy peak gives a good indicator of achieving saturation. The microeddy dampi…
Breath figures are the patterns formed when droplets condense on surfaces. We describe studies of such patterns that result when water condenses on the surface of a viscous oil. The average droplete diameter ⟨ D ⟩ exhibits two regimes of power law growth; at early times ⟨ D ⟩ ∼ t 0.3 and at late times ⟨ D ⟩ ∼ t . The…
Based on the idea that bonding energies of many substances can be modeled by pairwise interactions moderated by the local environment, we propose a new universal interatomic potential for tetrahedrally bonded materials. We obtain two basic relationships linking equilibrium interatomic distances and cohesive energies t…
The Mott-Hubbard gap U and the charge-transfer gap \ensuremath{\Delta} of solid NiO are estimated from ab initio calculations on the ${\mathrm{NiO}}_{6}^{10\mathrm{\ensuremath{-}}}$ cluster. Covalency in the essentially localized ${d}^{n}$ states and localization for the spatially extended O(2p) hole states are introd…
Schottky diodes were fabricated using gold and aluminum contacts to thin diamond films obtained by a microwave plasma assisted chemical vapor deposition process. The current-voltage and capacitance-voltage-frequency characteristics of these devices are similar to those fabricated on a crystalline diamond base formed b…
Symmetrically strained Si/Ge superlattices with an overall thickness of 0.2 \ensuremath{\mu}m, well above the critical thickness (\ensuremath{\cong} 10 nm) of unsymmetrically strained superlattices of the same composition, are studied. Strain adjustment is obtained by growing thin homogeneous ${\mathrm{Si}}_{0.4}$${\m…
Measurements performed on the in-plane thermoelectric power of first-stage graphite-acceptor intercalation compounds in the temperature range $3<T<300$ K are reported. At high temperature, the thermoelectric power is close to that obtained for higher-stage compounds while in the lower-temperature range it drops…
Small-angle x-ray scattering from the segmental density fluctuations of a starblock copolymer with a given arm number n of 6 as well as that of a linear diblock copolymer (corresponding to the starblock copolymer with n=1) were studied in both ordered and disordered states. In the ordered state the characteristic wave…
Raman spectra of LiClO4 complexed in poly(propylene-glycol) (PPG) have been obtained for concentrations of the monomer to salt ratio (ether oxygen):Li in the range 30:1–5:1. Splitting of the symmetric stretching mode of the ClO4− anion was observed with an intensity profile that varied with salt concentration. This ph…
Some characteristics of reversible phase-change optical data storage based on an amorphous-crystalline transformation in InSbTe alloys are given. The reversible phase change was observed in a wide region of composition. The laser amorphized spot of a ternary compound In3SbTe2 film could be crystallized using a diode l…
Band-structure calculations are presented for different lattice conformations of doped polyacetylene and polythiophene. At intermediate doping levels, the intraband transition energies are found to be in good agreement with experimental optical-absorption data for a soliton lattice conformation in polyacetylene and a…
A b initio calculations have been performed to study the structures and energies of intermediate-sized silicon clusters (Sin, n=7–10). All geometries have been optimized at the Hartree–Fock (HF) level of theory with the polarized 6-31G* basis set. The harmonic vibrational frequencies have been evaluated at the HF/6-31…