Materials Literature
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Magnetic oxides show a variety of extrinsic magnetotransport phenomena: grain-boundary, tunnelling and domain-wall magnetoresistance. In view of these phenomena the role of some magnetic oxides is outstanding: these are believed to be half-metallic having only one spin-subband at the Fermi level. These fully spin-pola…
A very general and versatile method for functionalizing different types of carbon nanotubes is described, using the 1,3-dipolar cycloaddition of azomethine ylides. Approximately one organic group per 100 carbon atoms of the nanotube is introduced, to yield remakably soluble bundles of nanotubes, as seen in transmissio…
Experiments have been carried out to study the effects of coke composition on combustion parameters and burn-off time in the regeneration of coke-deactivated supported alumina catalyst. At high temperatures, results showed that the combustion behaviour is dependent on coke type as oxidizable and reduceable coke profil…
TiC/TiN thin films deposited by reactive magnetron sputtering on Si (100) substrates were investigated by transmission electron microscopy for microstructure and by deep level transient spectroscopy (DLTS) for diffusion barrier against copper. TiN thin films deposited on Si substrates at a substrate temperature of 600…
The performance of tunable microwave devices based on heteroepitaxial YBa2Cu3Ox/SrTiO3 films on (001) LaAlO3 substrates has been evaluated. It was ascertained that “out-of-plane” SrTiO3 lattice parameter is the relevant factor in determining both device agility and dielectric loss. After high temperature annealing (11…
Multiwalled carbon nanotubes were grown using chemical vapor deposition on the tops of blunt vertical silicon posts in cells having a horizontal gate aperture of conventional field emitter design. We obtained over 1 mA total emission current from a single array, or 0.3 μA per cell at 40 V. In addition to the low volta…
Boron carbonitride (BCN) nanometric heterojunctions are controllably fabricated by bias-assisted hot-filament chemical vapor deposition with a pause-reactivation two-stage (PRTS) process. Tailored composition revulsion across the nanotube junction is obtained by simply varying the concentration of the gaseous precurso…
Novel mesoporus tin phosphates have been synthesized using alkyltrimethylammonium bromide (alkyl = C8-C18) as surfactant; the structure of the materials is stable at 500 degrees C. UV-VIS spectra show tetrahedral coordination of tin.
Arrays of Fe 1- x Co x (0.0⩽ x ⩽0.92) nanowires have been prepared by an electrochemical process, co-depositing Fe and Co atoms into the pores of anodic aluminium; their compositions were determined by atomic absorption spectroscopy. Transmission electron microscope results show that the nanowires are regularly spaced…
We report on the fabrication of single-crystalline thin films of RBa2Cu3O7−y (R: rare-earth element, R123) using an approach of vapor–liquid–solid tri-phase epitaxy. This method is based on application of pulsed-laser deposition under appropriate compositions and conditions predetermined from the relevant thermodynami…
The results of an adsorption isotherm investigation of methane on closed-ended single-wall nanotube bundles are presented. The isosteric heat of adsorption was determined as a function of the amount of methane adsorbed on the SWNT substrate for coverages in the first layer. The isosteric heat of adsorption is found to…
The band-edge electronic structure of spherical InP dots under electric fields is investigated using an atomistic pseudopotential approach. Field-induced changes in orbital energies, single-particle wave functions, transition intensities, and excitonic gaps are calculated. We find that interstate couplings profoundly…
Porphyrin dimers were prepared from beta,beta'-dipyrrole derivatives via the double pyrrolylmethylation followed by double [2 + 2] MacDonald porphyrin synthesis.
We present a comparative study of the behavior of electrodes modified with electropolymerized cobalt porphyrins and cobalt phthalocyanine films towards the electro-oxidation of 2-mercaptoethanol (2-ME). First, we report here on the electrochemical formation of the complex-based films and their characterization by cycl…
We study hole intraband relaxation in strongly confined CdSe quantum dots. We observe a dramatic reduction in the hole energy-loss rate in the final stage of hole relaxation at the bottom of the valence band. This reduction occurs because of a significantly increased inter-level spacing near the band edge, and, in par…
Electrical transport properties of intramolecular p–n–p junctions formed on individual semiconducting carbon nanotubes are reported. Chemical dopant “profiling” along the length of a nanotube divides the nanotube into two p-doped sections and a central n-doped section. The double p–n junctions formed on the nanotube d…
Electron injection into nanocrystal thin films is reversibly controlled by applying an electrochemical potential. Complete bleach of the visible interband transition and strong midinfrared intraband absorption are observed upon electron injection into the nanocrystal films. Quenching of the photoluminescence of the na…
We report laser oscillation at ∼610 nm in aggregates of ultrasmall elemental Si nanoparticles. The particles are ultrabright red emitting, dispersed from bulk Si by electrochemistry. The aggregates are excited by radiation at 550–570 nm from a mercury lamp. Intense directed Gaussian beams, with a threshold, manifest t…
In this letter, we report on the integration of epitaxial ferroelectric Pb(Zr, Ti)O3 (PZT) thin films on Si [100] substrates using a SrTiO3 (STO) template layer and a conducting perovskite (La0.5Sr0.5)CoO3 electrode. X-ray diffraction studies reveal both in-plane and out-of-plane alignment of the heterostructure. The…
We identify, by dislocation theory and molecular dynamics simulations, possible dislocation dipoles $(5|7|7|5$ and $4|8|8|4)$ as defect nuclei under tension in boron nitride nanotubes. The formation energies of the dipoles are then evaluated by ab initio gradient-corrected density functional theory. The $5|7|7|5$ dipo…