Materials Literature
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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…
A convenient microemulsion-mediated hydrothermal process was employed to synthesize ZnO nanowires, which exhibited a strong ultraviolet emission and a relatively weak defect emission. X-Ray diffraction, scanning electron microscopy, transmission electron microscopy and fluorescence spectroscopy were used to characteri…
The ferroelectricity of Bi4Ti3O12 (BIT), (Bi3.2La0.8)Ti3O12 (BLT), Bi4(Ti2.97V0.03)O12 (BTV), and (Bi3.2La0.8)(Ti2.97V0.03)O12 (BLTV) films prepared at 600 °C by metalorganic chemical vapor deposition was compared. For the BIT, BLT, BTV films deposited on (111)Pt/TiO2/SiO2/Si substrates, the ferroelectricity was not o…
We analyze low field hysteresis close to the demagnetized state in disordered ferromagnets using the zero temperature random-field Ising model. We solve the demagnetization process exactly in one dimension and derive the Rayleigh law of hysteresis. The initial susceptibility a and the hysteretic coefficient b display…
The hysteresis properties of ferromagnetic materials at low field are described by the Rayleigh law. We analyze the problem in light of modern statistical mechanics models of hysteresis. In particular, we compute the demagnetization curve and derive the Rayleigh parameters a and b in the random-field Ising model and i…
The modeling of the elastic properties of granular or nanoscale systems requires the foundations of the theory of elasticity to be revisited, as one explores scales at which this theory may no longer hold. The only cases for which a microscopic justification of elasticity exists are (nearly) uniformly strained lattice…
Epitaxial films of an oxide-diluted magnetic semiconductor with rutile structure, Mn-doped SnO2, have been fabricated by pulsed-laser deposition. As the Mn content increases, systematic changes in lattice constants and in-gap absorption are observed. Magnetization measurements show almost paramagnetic behavior. The in…
Photoinduced electron transfer in a size-quantized CdS/TiO2 composite system has been investigated using emission and transient absorption spectroscopy. Quantum-sized CdS and TiO2 particles were synthesized in reverse micelles using di-octyl sulfosuccinate (Aerosol-OT, AOT) as the surfactant stabilizer. The particle s…
Nanoparticles of cerium oxide with a narrow size distribution (±15%) are prepared by mixing cerium nitrate solution with an ammonium reagent. High-resolution transmission electron microscopy (TEM) indicates that over 99% of the synthesized particles are single crystals. TEM and photon absorption are used to monitor pa…
Much effort has been devoted to the study of the formation of superplastic in aluminum alloys on account of its cost and engineering advantages. From a mechanical point of view, the ability of a crystalline material to undergo superplastic behavior is usually linked to a submicrometer grain size. Equal channel angular…
Various kinds of fuels based on alcohols (methanol, ethanol, and isopropanol) and hydrocarbons (methane, ethane, and ethylene) were directly supplied to solid oxide fuel cells (SOFCs) to compare their power generation characteristics. The results on current-voltage characteristics and anodic polarization have revealed…
Dense amorphous poly(vinyl alcohol) (PVAL) built from a chain with 145 repeating units was studied by constant number of particles, pressure, and temperature-molecular dynamics simulations at temperatures between 400 and 527K. The results of the simulations were compared with pressure–volume–temperature data, solubili…
For the purpose of clarifying the reason why the discharge capacity of a misch metal (Mm)-based hydrogen storage alloy negative electrode in nickel-metal hydride battery drastically decreases at relatively low temperatures, the activation energies for hydrogen diffusion in the alloy bulk, charge-transfer reaction on t…
With an interest in obtaining data on laboratory glass samples to compare with simulated glasses produced by molecular dynamics computer simulations, we have explored, using calorimetric techniques, the fictive temperatures that can be obtained using different laboratory quenching methods. We describe some useful anal…
Ab initio calculations were carried out on zinc-porphyrins complexed to several amines: N-(3,5-dimethyl-pyridin-4-yl)-formamide, 1,4-diazabiciclo[2.2.2]octane (DABCO), and 1-azabiciclo[2.2.2]octane (quinuclidine). The proton chemical shifts of these complexes were calculated ab initio at the GIAO-HF/6-311G//HF/3-21G l…
*Reprinted from Star and Hyperbranched Polymers; Mishra, M.K., Kobayashi, S., Eds.; Marcel Dekker, Inc.: New York; 1999, 201–238.