Materials Literature
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We have fabricated fully vacuum-sealed 5 in. diagonal carbon nanotube field-emission displays of a gated structure with reliable electron emission characteristics. Single-walled carbon nanotube tips were implemented into the gate structure using self-aligned backside exposure of photosensitive carbon nanotube paste. A…
Pulse-current electrochemical deposition has been used to prepare Ni nanoparticles that are used as the catalysts for the growth of aligned carbon nanotubes. The nucleation site density of the Ni nanoparticles was controlled by changing the magnitude and duration of the pulse current. The aligned carbon nanotubes from…
Using ammonia as nitrogen source for molecular beam epitaxy, the GaN-based diluted magnetic semiconductor Ga1-xMnxN is successfully grown with Mn concentration up to x~6.8% and with p-type conductivity. The films have wurtzite structure with substitutional Mn on Ga site in GaN. Magnetization measurements revealed that…
We calculate the tunneling splittings in a Mn$_{12}$ magnetic molecule taking into account its internal many-spin structure. We discuss the precision and reliability of these calculations and show that restricting the basis (limiting the number of excitations taken into account) may lead to significant error (orders o…
Considering the model heat conduction problem in the setting of Grad's moment equations, we demonstrate a crossover in the structure of minima of the entropy production within the boundary layer. Based on this observation, we formulate and compare variation principles for solving the problem of boundary conditions in…
Resistivity and thermoelectric power (TEP) measurements on CeFe$_2$ and two of its pseudo-binaries Ce(Fe, 5% Ir)$_2$ and Ce(Fe, 7% Ru)$_2$ between 78K and 275K are reported. The resistivity data are analysed in terms of contributions from scattering due to phonon, magnon, spin fluctuation and lattice defects, and also…
Correlated atomic-force and fluorescence microscopy are used to study single-particle versus ensemble fluorescence quantum yields (QY) of semiconductor nanocrystals by measuring a simultaneous map of the topography and the single-particle fluorescence. CdSe/ZnS nanocrystal quantum dots and quantum rods with high QY we…
GaMnN thin films were synthesized using gas-source molecular-beam epitaxy. Mn concentrations between 3 and 12 at. % were investigated. No evidence of second-phase formation was observed by powder x-ray diffraction or high-resolution cross section transmission electron microscopy in films with 9% or less Mn. The films…
We present a theory of the infrared conductivity and absorption coefficients of metallic (III,Mn)V ferromagnetic semiconductors. We find that the conductivity is dominated by inter-valence-band transitions that produce peaks at $\hbar ω\sim 220 {\rm meV}$ and obscure the broadened Drude peak. We demonstrate that trans…
In the work the analysis of crystal chemical researches of nickel borocarbides RNi2B2C (R = rare earth) is given. The reasons of representation of dependence of Tc from crystal chemical parameters by two separate curves for magnetic and nonmagnetic R are considered. Common for all R dependences of Tc from crystal chem…
We establish the empirical correlation between Tc and crystal chemical parameters in diborides. Our results suggest that Tc of diborides can be higher 77K.
The relationship between crystal structure and electrochemical behavior through the lithium insertion in the perovskite oxides, Li y La (1 - y )/3 NbO 3 ( y = 0, 0.1, 0.25), has been investigated. The results of the relationship between the amount of inserted lithium and the number of vacancies reveal that Li + ions i…
Adsorption equilibria of toluene, dichloromethane, and trichloroethylene onto the pitch-based activated carbon fiber were obtained by the static volumetric method. Equilibrium measurements were done at (298, 323, and 348) K and pressures up to 3 kPa for toluene, 12 kPa for dichloromethane, and 6 kPa for trichloroethyl…
Carbon molecules were produced by evaporation of graphite and matrix-isolated in solid neon and argon. Using synchrotron radiation, the absorption spectra of the carbon clusters were recorded from 1100 to 5600 Å, and the fluorescence or phosphorescence spectra were recorded from 1200 to 9000 Å. We observed an intense,…
In this study we fractionated polystyrene- block -polyisoprene diblock copolymers (PS- b -PI) prepared by anionic polymerization into fractions which have a narrower distribution in molecular weight as well as in chemical composition. The strategy was to use two-dimensional HPLC: reversed phase HPLC to fractionate PI…
We report the synthesis and characterization of polyaniline integrally skinned asymmetric membranes (PANI ISAMs) and their use as chemical and electrochemical actuators. SEM characterization of a PANI ISAM cross section showed a thin dense skin and a microporous substructure with a PANI density gradient. The deformati…
A dipping technique was developed to coat colloidal crystal films with metals. It was found that nanosized metallic particles could be simply immobilized onto the monodisperse spheres in the colloidal crystal film. As one of the application of such films, silver-coated colloidal crystal films were used as the surface-…
Solid acids and especially those based on micelle-templated silicas and other mesoporous high surface area support materials are beginning to play a significant role in the greening of fine and specialty chemicals manufacturing processes. A wide range of important organic reactions can be efficiently catalyzed by thes…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetism of Lanthanides in Molecular Materials with Transition-Metal Ions and Organic RadicalsCristiano Benelli and Dante GatteschiView Author Information Department of Chemistry, University of Florence, UdR INSTM, Polo Scientifico Universitario, I 50019 Sesto Fiorentino, I…
The fine structures of low-temperature photoluminescence (PL) spectra of TiO 2 thin films with addition of ZnFe 2 O 4 (ZnFe 2 O 4 /TiO 2 composite films) are firstly reported. The films were deposited on quartz substrates by radio-frequency magnetron sputtering method. It is shown that different phase structures are d…