Materials Literature
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The amount of screening of a proton in a metal, migrating under the influence of an applied electric field, is calculated using different theoretical formulations. First the lowest order screening expression derived by Sham (1975) is evaluated. In addition 'exact' expressions are evaluated which were derived according…
A cluster consisting of many atoms or molecules may be considered, in some circustances, to be a single large molecule with a well defined polarizability. Once the polarizability of such a cluster is known, one can evaluate certain properties, e.g. the cluster's van der Waals interactions, using expressions derived fo…
We studied the crystal and magnetic structure of the ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ compound for $(0.11\ensuremath{\leqslant}x\ensuremath{\leqslant}0.175)$ using stoichiometric samples. For $x<0.13$ the system's ground state is insulating canted antiferromagnetic. For $0.13\en…
The photocatalytic characteristics of the tetrapod-branched ZnO nanostructures synthesized by thermal evaporation method are investigated. The fitting of absorbance maximum plot versus time indicates an exponential decay, suggesting the photodegradation of Rhodamine B catalyzed by the ZnO nanotetrapod is a pseudo firs…
The intraband relaxation between the 1Pe and 1Se state of CdSe colloidal quantum dots is studied by pump-probe time-resolved spectroscopy. Infrared pump-probe measurements with approximately 6-ps pulses show identical relaxation whether the electron has been placed in the 1Se state by above band-gap photoexcitation or…
A series of copper-doped zinc oxide films were grown by pulsed-laser ablation. Films grown under conditions that produced n-type ZnO were nonmagnetic while those grown under conditions that produced p-type were ferromagnetic with a Curie temperature above 350 K. The magnetic moment per copper atom decreased as the cop…
The electric transport properties of an individual vertical multiwall carbon nanotube (MWCNT) were studied in situ at room temperature in a scanning electron microscope chamber. It was found that the single MWCNT has a large current-carrying capacity, and the maximum current can reach 7.27 mA. At the same time, a very…
The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is…
We present a detailed electron diffraction study of individual single-walled carbon nanotubes. A novel sample preparation procedure provides well-separated, long and straight individual single-shell nanotubes. Diffraction experiments are carried out at 60kV, below the threshold for knock-on damage in carbon nanotubes.…
We study the temporal growth pattern of surface fluctuations on a series of spinodally unstable polymer films where the degree of instability is controlled by the film thickness. For films in the deep spinodal region, the growth rate function of the surface modes as a function of the wavevector,, fits well to the mean…
The first synthesis of a series of glutamic acid based dendrimers having a central ferrocene core is described. The materials were fully characterized spectroscopically and display strong intramolecular H-bonding. This H-bonding can be disrupted with DMSO. The redox properties of the core are attenuated by the increas…
Great effort has been expended in the development of methods to purify raw nanotubes by chemical treatment, washing, mechanical filtration, or heat treatment in a vacuum or oxidative environment. These techniques are limited by incomplete removal of catalyst nanoparticles and by the damage to the nanotubes that often…
Abstract We report a crystal structure, bond lengths, and magnetic properties of a Prussian blue analogue, CsCu[Cr(CN)6]·2.1H2O. This compound has a tetragonal structure (), which is caused by the strong cooperativity due to the Jahn–Teller effect of CuII and shows ferromagnetism with Curie temperature of 65 K.
The structure and the rheological properties of thermoplastic elastomer gels composed of polystyrene- block -polybutadiene- block -poly(methyl methacrylate) triblock copolymer (SBM) in a selective solvent for the midblock have been investigated over a wide range of concentrations. At low polymer concentration, the S a…
A theoretical comparative study of complexes of porphyrin (P), porphyrazine (Pz), phthalocyanine (Pc), porphycene (Pn), dibenzoporphycene (DBPn), and hemiporphyrazine (HPz) with iron (Fe) has been carried out using a density functional theory (DFT) method. The difference in the core size and shape of the macrocycle ha…
[reaction: see text] A series of novel nanosized pi-conjugated molecules based on both truxene and porphyrin moieties with high fluorescence quantum yields have been prepared via the Suzuki cross-coupling and the Lindsey reactions. The investigation of optical properties demonstrates that various aryl groups as the an…
We combine here a regularization procedure with individual adsorption isotherms obtained from grand canonical Monte Carlo simulations in order to obtain reliable pore size distributions. The methodology is applied to two hexagonal high-ordered silica materials: SBA-15 and PHTS, synthesized in our laboratory. Feasible…
Abstract Very fine nickel nanoparticles with diameters of 2.5 ± 1.5 nm have been prepared by reduction of anhydrous nickel(II) chloride with lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) in THF at room temperature.
Aqueous dispersions of single-walled carbon nanotubes (SWCNT) with polymers were characterized by small-angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM). Two types of polymers were used: an alternating copolymer of styrene and sodium maleate (PSSty) and gum arabic (GA) a highly bran…
Single-walled and multiple-walled carbon nanotubes were functionalized with derivatized polyimide for the homogeneous dispersion of the nanotubes. For the functionalization, the nanotube-bound carboxylic acids derived from the surface defects were targeted for esterification reactions with pendant hydroxyl groups in t…