Materials Literature
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We suggest a new approach to theory of contact thermoelectric cooling (Peltier effect). The metal–metal, metal–n-type semiconductor, metal–p-type semiconductor, p–n junction contacts are analyzed. Both degenerate and nondegenerate electron and hole gases are considered. The role of recombination in the contact cooling…
We describe a method to produce high-crystalline quality multiwalled carbon nanotubes from carbon black. By modifying the arc into a high-temperature oven, carbon black is converted into carbon nanotubes by a solid-state transformation without a catalyst. This process sheds new light onto the growth mechanism of carbo…
Electron spin echo envelope modulation (ESEEM) experiments with aqueous complexes of Gd3+ and Mn2+ have shown that a common and unusual feature of the primary ESEEM spectra of such high spin/weak crystal field systems is an extremely low intensity of the sum combination line. Numerical simulations of the ESEEM spectra…
Successful integration of Ba1−xSrxTiO3 (BST) based thin films with affordable Si substrates has a potential significant commercial impact as the demand for high-frequency tunable devices intensifies. This work evaluates the material properties of postdeposition annealed Ta2O5 thin films fabricated via the metalorganic…
Dielectric measurements (10−2–109 Hz) on plastically crystalline cyanocyclohexane reveal a glass transition where the rotational dynamics freezes at a vitrification temperature Tg=134 K. A full line-shape analysis of the dielectric loss spectra, which include a pronounced secondary relaxation contribution (β process)…
We have investigated high-excitation photoluminescence properties of CuI thin films with a thickness of 100 nm grown on a NaCl substrate by vacuum deposition. The energies of the heavy-hole and light-hole excitons in the CuI thin film are split at low temperatures by the thermal strain resulting from the difference in…
The dielectric and electrically induced strain characteristics of Fe-substituted Pb(Zn1/3Nb2/3)O3–PbTiO3 single crystals have been investigated. These investigations have shown that Fe substitution results in: (i) a lowering of the field level required to obtain large strains, (ii) an increased squareness in the ε−E r…
In order to study the effects of penetrability in mixtures of dissimilar particles we consider hard (colloidal) spheres and penetrable spheres. The latter may be taken to represent ideal, noninteracting polymer coils. Polymers and colloids interact by means of a repulsive step-function pair potential, which allows for…
Polycyclic aromatic hydrocarbons (PAHs) have been employed as models to investigate the functionalization of SWNTs sidewalls with transition metal complexes at the NL-DFT level, pointing out the most favorable coordination sites and the electronic properties of the resulting system. Molecular fragments topologically r…
A principle of planar-type visible light emission is presented using ballistic electrons as excitation source. The device is composed of a semitransparent top electrode, a thin film of fluorescent material, a nanocrystalline porous silicon (nc-PS) layer, an n-type silicon wafer, and an ohmic back contact. When a posit…
Infrared dielectric function spectra and phonon modes with polarization parallel and perpendicular to the c axis of high quality, highly relaxed, and single crystalline wurtzite MgxZn1−xO films with 0⩽x⩽0.2 prepared by pulsed-laser deposition on c-plane sapphire substrates were obtained from infrared spectroscopic ell…
Large pore (a = 150-200 A) wormlike and highly oriented cubic (IM3m space group) and 2D-hexagonal (P6m) mesostructured xerogels have been reproducibly synthesised by Evaporation-Induced Self Assembly (EISA). Mesostructure control was attained by changing the template (nonionic block copolymer) and water (h = [H2O]/[Si…
A tantalum–pentoxide dielectric with an enhanced permittivity of over 50 was found to be crystallized in a hexagonal symmetry with a=0.628 nm and c=0.389 nm. The incommensurate epitaxy of tantalum pentoxide on hcp-ruthenium metal stabilizes the hexagonal phase with √3-time periodicity in plane, as compared with that o…
Photoluminescence and electroluminescence from a Si/SiO2 superlattice have been measured. They show similar characteristics and exhibit an inhomogeneously broadened photoluminescence band peaked at 2.06 eV. The excitation spectrum indicates that excitations occur in the Si layers. The insensitivity of the luminescence…
A highly sensitive molecular thermometer based on platinum octaethyl porphyrin, which can be employed in a range of environments, is presented. The thermal activation of the emission spectrum results in a change in emission intensity by an order of magnitude over a temperature range of 45 K about room temperature. The…
Magnetic entropy change ΔS of compounds La(Fe1−xCox)11.2Si1.8 with the cubic NaZn13-type structure was investigated around their Curie temperature TC. It is found that the phase transition is completely reversible, indicating a nature of second order phase transition. The maximum value of |ΔS|∼13.0 J/kg K under a fiel…
Static and high-frequency magnetic properties have been studied for BaFe12−2xCoxZrxO19 with x=0–1.2. The x-ray diffraction and M–H curves of aligned samples show that Co–Zr substitution can modify the anisotropy of BaFe12−2xCoxZrxO19. BaFe12−2xCoxZrxO19 with x⩽0.6 has an easy c-axis anisotropy and the anisotropy field…
The phase diagram of the Gay–Berne model with anisotropy parameters κ=3, κ′=5 has been evaluated by means of computer simulations. For a number of temperatures, NPT simulations were performed for the solid phase leading to the determination of the free energy of the solid at a reference density. Using the equation of…
Mn x Ni 0.5−x Zn 0.5 Fe 2 O 4 ferrites with x=0.05, 0.1, 0.2, 0.3, and 0.4, have been synthesized by the citrate precursor method and investigated for their magnetic properties. The initial relative permeability is observed to increase with increase in manganese concentration up to x=0.2 followed by a decrease, the ma…
We studied photoluminescence (PL) properties of eighteen samples of wurtzite ZnO/MgxZn1−xO multiple quantum wells (x=0.12 and 0.27) with various well widths (Lw) of 0.7–4.65 nm. Radiative recombination of the electron–hole pairs that are spatially separated due to the quantum-confined Stark (QCS) and Franz–Keldish (QC…