Materials Literature
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In this work we present an exhaustive, experimental and theoretical, investigation on the structural, vibrational, electronic, and energetic properties of TS-1 catalyst. The perturbation induced by adsorption of water and ammonia ligands, which represent two key molecules in the industrial processes catalyzed by TS-1,…
A series of cyanide-bridged, iron(II) spin-crossover coordination polymers of formula Fe(py) 2 [M(CN) 4 ] (M = Pd or Pt; py = pyridine) and Fe(pz)[M(CN) 4 ]·2H 2 O (M = Ni, Pd, or Pt; pz = pyrazine) have been studied by recording the Raman and infrared (IR) spectra of their low-spin (LS) and high-spin (HS) forms in th…
Abstract The structure of binary (PbO) x (P 2 O 5 ) (1− x ) glasses was investigated using Raman scattering and infrared spectroscopy, over the compositional range x = 0.5–0.68. The distribution of the phosphate groups (PO 2 ) − , (PO 3 ) 2− , (P 2 O 7 ) 4− and (PO 4 ) 3− , determined from the simulation of Raman spec…
Partially aliphatic, high molecular weight polyimide copolymers were successfully synthesized using an ester−acid high-temperature solution imidization route by which noncrystalline, soluble materials were obtained. Variations in the aliphatic content produced a series of polyimides having different glass transition t…
The glass of composition Na 2 O·CaO·2SiO 2 was modified upon addition of ZnO to obtain the series of glasses Na 2 O·CaO·2SiO 2 · x ZnO ( x = 0.17, 0.34, 0.68), where x = 0.68 is the experimentally determined maximum zinc content that does not produce phase separation. The glasses were investigated by means of density…
${\mathrm{Pr}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{CoO}}_{3}$ showed a simultaneous metal-insulator and paramagnetic-paramagnetic spin-state transition of the first-order type at 90 K accompanied by a volume contraction by $\ensuremath{\sim}2%.$ Neutron diffraction analysis revealed that the volume contraction is mainly…
We investigate the lifetime of {\it d} holes in copper within a {\it first--principle} $GW$ approximation. At the $G_0W_0$ level the lifetime of the topmost {\it d} bands are in agreement with the experimental results and are four times smaller than those obtained in the ``on--shell'' calculations commonly used in lit…
Time-resolved Kerr microscopy is used to study the excitations of individual micron- scale ferromagnetic thin film elements in their remnant state. Thin (18 nm) square elements with edge dimensions between 1 and 10 $μ$m form closure domain structures with 90 degree Neel walls between domains. We identify two classes o…
The low-frequency Raman coupling coefficient $C(\ensuremath{\nu})$ of 11 different glasses is evaluated. It is shown that the coupling coefficient demonstrates a universal linear frequency behavior $C(\ensuremath{\nu})\ensuremath{\propto}(\ensuremath{\nu}/{\ensuremath{\nu}}_{\mathrm{BP}}+B)$ near the boson peak maximu…
We report on the electrodynamics of a Heusler alloy ${\mathrm{Fe}}_{2}\mathrm{TiSn}$ probed over 4 decades in energy: from the far infrared to the ultraviolet. Our results do not support the suggestion of Kondo-lattice behavior inferred from specific-heat measurements. Instead, we find a conventional Drude-like respon…
Gold catalysts supported on TiO 2 and TiO 2 /SiO 2 were used in gas-phase propene epoxidation with a hydrogen−oxygen mixture. The catalysts were characterized by 197 Au Mössbauer absorption spectroscopy (MAS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Gold particle sizes of 1…
A model for diamond nucleation by energetic species (for example, bias-enhanced nucleation) is proposed. It involves spontaneous bulk nucleation of a diamond embryo cluster in a dense, amorphous carbon hydrogenated matrix; stabilization of the cluster by favorable boundary conditions of nucleation sites and hydrogen t…
Digestive ripening, heating a colloidal suspension at or near the solvent boiling point in the presence of a surface-active ligand, was applied to polydisperse colloidal gold in toluene using a series of alkylthiols, viz., octyl-, decyl-, dodecyl-, and hexadecylthiols. In all the instances, digestive ripening signific…
We have investigated the electrical transport properties of carbon nanotube field-effect transistors as a function of channel length, gate dielectric film thickness, and dielectric material. Our experiments show that the bulk properties of the semiconducting carbon nanotubes do not limit the current flow through the m…
Gold nanoparticles ranging in diameter from 1 to 8 nanometers were prepared on top of silicon wafers in order to study the size dependence of their oxidation behavior when exposed to atomic oxygen. X-ray photoelectron spectroscopy showed a maximum oxidation resistance for "magic-number" clusters containing 55 gold ato…
We demonstrate a novel synthetic scheme that can be used to differentially guide the shape of PbS semiconductor nanocrystals. Our study first demonstrates the discovery of single-crystalline star-shaped nanocrystals as novel transient species. We then carefully probe their shape evolution toward other novel nanostruct…
The larval shells of the marine bivalves Mercenaria mercenaria and Crassostrea gigas are investigated by polarized light microscopy, infrared spectroscopy, Raman imaging spectroscopy, and scanning electron microscopy. Both species contain similar shell ultrastructures. We show that larval shells contain amorphous calc…
Molecular dynamics (MD) simulations in three dimensions have been performed for a fluid with particles interacting with a continuous version of the Stell-Hemmer core-softened potential that in two dimensions has been known to reproduce most of the static and dynamic anomalies of liquid water. The pair distribution fun…
Copper electrodeposit was obtained in CuSO4+H2SO4 electrolyte solution by electrodeposition and its structure was studied by XRD. The results showed that copper electoddeposits with the highly preferred orientations of (220) and (111) could be obtained at current density 4.0 A/dm2 and 15.0 A/dm2, respectively. The tex…
The complex dielectric permittivity of 4-(2- hexyloxyethoxy)4'-cyanobiphenyl (6O2OCB) enclosed in porous samples of ZrO2 has been studied in the frequency range 10−1–106 Hz and over a wide temperature range. For the substance in the nearly spherical pores of ZrO2 no phase transition has been found, while for the subst…