Materials Literature
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Carbon nanotube junctions are of great interest in the fundamental research and nanoelectronic applications. Identical carbon nanotube Y junctions have been successfully synthesized by pyrolysis of methane over cobalt supported on magnesium oxide. The Y junctions have very straight arms with uniform diameters, and the…
Formation and decay of nonbridging oxygen hole centers (NBOHC, an oxygen dangling bond) in SiO2 glasses by F2 excimer laser (7.9 eV) irradiation were in situ analyzed by monitoring 1.9 eV photoluminescence of NBOHC using a pump and probe technique. In wet SiO2, the SiO–H bond was efficiently photolyzed by F2 laser pho…
Bergman cyclization of 2,3-dialkynyl-meso-tetraphenylporphyrins and carbon–carbon bond formation (mediated by 1,4-diradicals) with the adjacent meso-phenyl rings lead to formation of an unprecedented multicarbocycle fused onto the porphyrin periphery. The highly π-extended parent molecules (1; R=Bu, H, Ph) are describ…
Frequency upconversion into green and red luminescence in erbium–ytterbium-codoped phosphate glass pumped with a 970 nm diode laser is presented. The red upconversion emission results from a two-photon excitation process. The green emission results from a two- or three-photon excitation process with the two-photon pro…
An electronic switch at the molecular level has been realized by using a class of ionic compounds of the formula [Co(L)(diox)]Y (L = tetraazamacrocyclic ligand, Y = mononegative anion). Such compounds undergo temperature- and pressure-induced intramolecular one-electron transfer equilibria. The transition temperature…
A method is presented to determine the particle size and internal strain from broadened x-ray peaks obtained on small coherent domains containing dislocations. In contrast with the evaluation techniques applied earlier, the proposed procedure requires only the measurement of a single line profile. It is based on the a…
Using a mean-field equation of state we calculate the density-concentration phase diagrams for a binary mixture of repulsive Gaussian core particles over a range of size ratios. A simple mean-field density functional (DFT) approach, equivalent to the random phase approximation, is used to calculate the surface tension…
The largest tungstoarsenate(III) known to date is [AsW65O217(H2O)7]26− (1). This novel polyoxoanion is isolated as its potassium salt in aqueous, acidic medium in good yield. Structural characterization is based on single-crystal X-ray diffraction, 183W NMR, FT-IR spectroscopy, and elemental analysis. The compact stru…
The ionic conductivity of isometric pyrochlore, ideally A2B2O (7), is extremely sensitive to disordering of A- and B-site cations and oxygen anion vacancies. We report the first use of ion beam irradiation-induced disordering in Gd 2Ti 2O (7) to produce a strain-free, buried, disordered defect-fluorite layer approxima…
A MnBi alloy containing over 90 wt % low-temperature phase (LTP) has been obtained by high-temperature sintering and magnetic purification. The coercivity of the bonded MnBi magnet increases with increasing temperatures. A coercivity of 2.0 T has been achieved at 400 K. The maximum energy product (BH)max of the magnet…
We present ab-initio calculations for the in plane conductivity of Co/Cu multilayer slabs. The electronic structure of the multilayer slabs is calculated by means of density functional theory within a screened KKR scheme. Transport properties are described using the Boltzmann equation in relaxation time approximation.…
We present a new density-matrix functional within the recently introduced framework for tensor-product expansions of the two-particle density matrix. It performs well both for the homogeneous electron gas as well as atoms. For the homogeneous electron gas, it performs significantly better than all previous density-mat…
Complementary theoretical modeling methods are presented for the classical and quantum Heisenberg model to explain the magnetic properties of nanometer-sized magnetic molecules. Excellent quantitative agreement is achieved between our experimental data down to 0.1 K and for fields up to 60 Tesla and our theoretical re…
Extracting large field-emission currents from individual single-walled carbon nanotubes degrades their current–voltage behavior and changes the nanotube structure. Field-emission microscopy observations and field-emission current–voltage measurements revealed behavior characteristic of local heating, followed by therm…
We have developed a formulation of density functional perturbation theory for the calculation of vibrational frequencies in molecules and solids, which uses numerical atomic orbitals as a basis set for the electronic states. The (harmonic) dynamical matrix is extracted directly from the first order change in the densi…
Properties of (10, 10) single-walled carbon nanotubes under uniaxial pressure are investigated by means of pressure-controlled molecular dynamics simulations using an order- N tight-binding method. We use an extended Andersen method in order to control pressure of system. This scheme allows us to investigate the press…
Polymer layered-silicate (clay) nanocomposites have the unique combination of reduced flammability and improved physical properties. These results led to a NIST-industrial consortium which investigated the flammability properties of these nanocomposites further. A series of thermoplastic polymer nanocomposites were st…
This review paper surveys two decades of research in which functional groups on polymers have been utilized to form more fire-resistant structures under fire-exposure conditions. Examples are polyaramides which convert to polybenzoxazoles, nitrile polymers with latent catalysts for triazine ring formation, styrylpyrid…
The inhibitory properties of (methylenecyclopropyl)formyl-CoA (MCPF-CoA), a metabolite derived from a natural amino acid, (methylenecyclopropyl)glycine, against bovine liver enoyl-CoA hydratase (ECH) were characterized. We have previously demonstrated that MCPF-CoA specifically targets ECHs, which catalyze the reversi…
We have observed a photoinduced phase transition (PIPT) in a spin-crossover Fe (II) complex Nafion–[Fe(Htrz) 3 ] film (Nafion is an ion exchange polymer film, and Htrz=1, 2, 4-1H-triazole) from a low-spin (LS) state ( S =0) to a high-spin (HS) state ( S =2) below 150 K. The phototransferred HS state relaxes to the ini…