Materials Literature
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We Study in this paper the scaling and statistical properties of the $ac$ conductivity of thin metal-dielectric films in different regions of the loss in the metallic components and particularly in the limit of vanishing loss. We model the system by a 2D $RL-C$ network and calculate the effective conductivity by using…
Temperature dependent optical conductivity spectra of a ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ (LCMO) sample were measured. In the metallic regime at very low temperatures, they clearly showed two types of absorption features, i.e., a sharp Drude peak and a broad midinfrared absorption band, which…
Method of invariants is used to obtain effective kp-Hamiltonian with position-dependent band parameters and correct boundary conditions for electron and hole envelope functions in A3B5-heterostructures with arbitrary interface orientation. It is shown that the presence of heterointerface yields additional quadratic-in…
Dimensional stability is crucial to possible applications of single-walled nanotubes, as their properties are linked to size and topology. We observe nanotubes responding to uniform atom loss, through surface reconstruction and drastic dimensional changes. Experiments using electron irradiation evidence nanotube diame…
We report on the field emission properties of single-wall carbon nanotube films, with emphasis on current–versus–voltage (I–V) characteristics and current stability. The films are excellent field emitters, yielding current densities higher than 10 mA cm−2 with operating voltages that are far lower than for other film…
Thermodynamics and transport properties of a dissipative particle in a tight-binding model are studied through specific heat and optical conductivity. A weak coupling theory is constituted to study the crossover behavior between the low-temperature region and the high-temperature region analytically. We found that coh…
During the preparation of a fluorescent conjugate based on a manganese cationic porphyrin carboxylate derivative linked to a 5'-amino-3'-fluorescein-labeled oligonucleotide, we observed the chemical transformation of the thiourea linkage to a guanidinium function during the deprotection in ammonia of the 3'-fluorescei…
Preferential (001) orientation CeO2 films have been successfully grown on biaxially textured Ni substrates using ion beam assisted pulsed laser deposition. The x-ray diffraction (XRD) patterns for the CeO2 films and target have been measured. The in-plane lattice constants have been derived from the data of XRD. It wa…
We report the investigation of the steady-state Hall mobility and carrier concentration behavior depending on extrinsic light excitation intensity, wavelength and temperature in n-type liquid-encapsulated Czochralski (LEC) GaAs crystals. The carrier concentration of the samples measured in the dark ranged from 108 to…
The kinetics of release into water of particulate NaCl (used here as an example of a highly water-soluble solute) incorporated in a cellulose acetate (CA) matrix was investigated in correlation with the concurrent variation of the water content of the matrix. To ensure comparability with the kinetic behavior of sparin…
We report a Raman study of the effects pressure has on the vibrational structure of ${\mathrm{Ge}}_{n}{\mathrm{Si}}_{m}$ multiple quantum wells (MQW's) with $n<~4$ and $m<~7.$ Three primary phonon bands are studied: Ge-Ge within the germanium layers, Si-Si within the silicon layers, and the Ge-Si interface mode.…
On the basis of the Fermi liquid theory, we investigate the many-body effect on the Drude weight. In a lattice system, the Drude weight $D$ is modified by electron-electron interaction due to Umklapp processes, while it is not renormalized in a Galilean invariant system. This is explained by showing that the effective…
The structure and defects of thin epitaxial ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}(0001)$ overlayers on Cr(110) films have been investigated by grazing incidence x-ray diffraction. Cr(110) films were prepared by molecular beam epitaxy before exposing them to a controlled oxygen atmosphere in the temperature range 400--800…
We have no evidence of intrinsic surface states in the band gap for in situ fractured SrTiO3:La, SrTiO3:Nb and SrTiO3. The valence band maximum of the samples lie at 3.3 eV below the Fermi level, indicating that the band bending is negligibly small. No emission from the region of bulk band gap indicated that the intri…
The permeabilities and selectivities of O3, O2, and N2 through silicone capillary membranes employed to degrade organic pollutants in water or air have been experimentally determined. These characteristics have been studied for silicone membranes used in membrane reactors having the following conditions: O3 in O2 on o…
Two-peak photoluminescence (PL), blue and red, is obtained in the long-time aged porous silicon samples that were initially anodized under ${\mathrm{Ar}}^{+}$ 488 nm laser illumination. Static and dynamic photoluminescence, photoluminescence excitation, and Fourier transformation infrared absorption and reflection spe…
A new structural model of an Al 72 Ni 20 Co 8 decagonal quasicrystal is constructed on the basis of high-angle annular dark-field images and high-resolution electron microscope images. The model is composed of two types of atom clusters with about a 0.4 nm radius as basic structural units, which are similar to the uni…
Carrier-type reversal $(p$ to $n)$ has been observed, in ${\mathrm{Pb}}_{x}{\mathrm{Ge}}_{42\ensuremath{-}x}{\mathrm{Se}}_{48}{\mathrm{Te}}_{10}$ glasses $(0<~x<~20)$ at 8 at. % of lead. dc electrical resistivity (\ensuremath{\rho}) and activation energy for electrical conduction $(\ensuremath{\Delta}E)$ are fou…
We report a comprehensive charge transport study of ion-implanted rigid rod and ladder polymers $p$-phenylenebenzobisoxazole, $p$-phenylenebenzobisthiazole, and benzimidazobenzophenanthroline. The three pristine materials are strong and stable polymers with a room temperature conductivity ${\ensuremath{\sigma}}_{\math…
We report photoluminescence (PL) data on amorphous ${\mathrm{SiO}}_{2}$ in the spectral range of the \ensuremath{\alpha} (4.3 eV), \ensuremath{\beta} (3.1 eV), and \ensuremath{\gamma} (2.7 eV) emissions excited with synchrotron radiation. Differently prepared and treated samples are compared. Neutron irradiation gives…