Materials Literature
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The chemical pathways leading to gamma-prime(L1_2)-nucleation from nondilute Ni-5.2 Al-14.2 Cr at.%, gamma(f.c.c.), at 873 K are followed with radial distribution functions and isoconcentration surface analyses of direct-space atom-probe tomographic images. Although Cr atoms initially are randomly distributed, a distr…
We report experimental observation of Kondo-Fano resonant tunneling in Si-doped GaAs/AlAs multiple quantum wells. The spectrum of differential tunneling conductance at low bias shows a strong temperature dependent resonance, whose peak is split in the presence of a magnetic field, characteristic of a Kondo resonance.…
We combine ab initio density functional theory with transport calculations to provide a microscopic basis for distinguishing between good and poor metal contacts to nanotubes. Comparing Ti and Pd as examples of different contact metals, we trace back the observed superiority of Pd to the nature of the metal-nanotube h…
We present the first surfactant-free inverse emulsion polymerization by using organically modified clay platelets as stabilizers. Colloidally stable inverse Pickering emulsions of aqueous acrylamide (AAm) or 2-hydroxyethyl methacrylate (HEMA) in cyclohexane stabilized by hydrophobic Cloisite 20A (MMT20) were prepared.…
A theoretical investigation has been made on the phonon spectrum and heat capacity of polymorphs of carbon and boron nitride with special interests on the variation of Debye temperature and stiffness with temperature. A part of optical phonon branches of graphite exhibits higher frequencies than those of diamond. As a…
A novel technique for fabricating hollow silica spheres (see figure) via a one-step process is described. The positively charged template polystyrene particles are “dissolved” subsequently, even synchronously, as the silica layer is formed in the same medium. Hollow silica spheres are formed, and neither additional di…
Abstract This paper is a review of polymer nanocomposites used for flame retardancy applications, including commercial materials and open literature examples. Where possible, details on how the nanocomposite and flame retardant work together will be discussed. The key lesson from this review is that while the polymer…
Silver nanoparticles with a single (111) twin were selectively nucleated and grown for the first time to produce right bipyramids 75-150 nm in edge length. Key to the production of single twinned seeds was the addition of NaBr to a polyol synthesis in which AgNO3 is reduced by ethylene glycol in the presence of poly(v…
We report on the effects of Lewis bases and other ligands on radiative recombination in CdSe quantum dots (QDs) in several solvents. Long-chain primary amines are found to be the most efficacious capping agents for CdSe QDs in nonpolar solvents. Primary alkylamines are superior to secondary and tertiary alkylamines. T…
Roll the Dy's: Two aggregates made up of dysprosium triangles (one example is shown) display a vanishing susceptibility at low temperature, unprecedented in systems comprising an odd number of unpaired electrons. Despite having a near non-magnetic ground state, behavior typical of a single-molecule magnet is observed…
We report a size dependence of Young's modulus in [0001] oriented ZnO nanowires (NWs) with diameters ranging from 17 to 550 nm for the first time. The measured modulus for NWs with diameters smaller than about 120 nm is increasing dramatically with the decreasing diameters, and is significantly higher than that of the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleChemistry of Carbon NanotubesDimitrios Tasis, Nikos Tagmatarchis, Alberto Bianco, and Maurizio PratoView Author Information Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research F…
Preliminary EELS and EDS analyses undertaken on CaCu 3 Ti 4 O 12 ceramics, sintered for 3 and 24 hrs at 1100°C in air, have suggested that there are differences in the composition and valence of the Cu and Ti at grain boundaries as compared with the bulk composition. For the 3 hour sinter a change was observed in the…
We here present a high-level ab initio study of the thermochemistry of the chromium hydroxides Cr(OH)n, n = 2-6, and of the oxyhydroxide CrO(OH)4. Optimum geometries and harmonic vibrational frequencies were determined at the B3LYP level of theory using basis sets of triple-zeta quality including polarization and diff…
The feasibility of applying the single-charge rotational foam molding processing principle to the fabrication of integral skin polypropylene (PP) foams comprising a PP solid skin and a PP foamed core is investigated in this study. A systematic process interruption and sample evaluation approach was used to quantify th…
Zinc oxide is an important semiconducting and piezoelectric material. Structurally, due to the three types of fast growth direction: <0001>, <01 0> and <2 0> as well as the ±(0001) polar surfaces, a diversity group of ZnO nanostructures have been grown in our laboratory: including nanocombs, nanosaws, nanosprings, nan…
First-principle density functional theory (DFT) calculations on the electronic state and structure of a [Co2+]2/gamma-Al2O3 model catalyst have been performed in relation to catalysis for unique NO-CO reactions on a Co2+ ensemble/gamma-Al2O3 catalyst. The DFT calculations reveal that a bulk structure of gamma-Al2O3 is…
Nanosized tin-doped indium oxide (ITO) powders were prepared by hydrothermally treating either the coprecipitated hydroxides of tin and indium gels with the addition of a small amount of urea or the solution of indium and tin aqueous salts in presence of urea at 240°C for about two days followed by calcination at 600°…
The increase in viscosity that is observed in attractive colloidal systems by varying the temperature or the volume fraction can be related to the formation of structures due to particle aggregation. In particular we have studied the nontrivial dependence of the viscosity from the temperature and the volume fraction i…
The hindered rotor scheme, originally developed for internal rotors in flexible chains (Van Speybroeck, V.; Van Neck, D.; Waroquier, M.; Wauters, S.; Saeys, M.; Marin, G. B. J. Phys. Chem. A 2000, 104, 10939), is extended to puckering motions in four-membered rings. The applicability of the approach is tested in a var…