Materials Literature
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The influence of molecular vibrations on dissociative adsorption is studied by six-dimensional quantum dynamical calculations. For the system H_2 at Pd(100), which possesses non-activated pathways, it is shown that large vibrational effects exist and that they are not due to a strongly curved reaction path and a late…
Using high-frequency EPR spectroscopy we have found that a cluster comprising eight iron(III) ions, Fe 8 , which is essentially flat, has a ground S = 10 state and an Ising-type anisotropy. For the first time both ac susceptibility and Mössbauer spectroscopy could be used in order to monitor the relaxation time of the…
Abstract Magnesium and calcium antimonites, which can coexist with MgO and CaO, respectively, were synthesized by a phase-equilibration technique and identified by X-ray diffraction to be MgSb 2 O 4 and Ca 4 Sb 2 O 7 . To determine the standard Gibbs energies of formation of those antimonites, emf values of the follow…
Nonahalocyclopentasilanes, HSi 5 X 9, and octahalocyclopentasilanes, H 2 Si 5 X 8 (X = Cl, Br, I), were prepared by dearylation of the corresponding phenylated cyclosilanes HSi 5 Ph 9 and H 2 Si 5 Ph 8 with gaseous hydrogen halides and catalytic amounts of aluminum halides (HX/AlX 3 ) dissolved in benzene. The product…
A brief overview of the novel technology of self-reinforced composites based on liquid crystalline polymer (LCP)/thermoplastic and LCP/LCP blends is presented. Various aspects of the composite technology are considered including mixing, transition temperatures, factors governing LCP fibrillations, enhancement of cryst…
The heterogenization of chiral homogeneous catalysts is possible by occluding them in polydimethylsiloxane membranes. Examples are the synthesis of the first heterogeneous Jacobsen catalyst, which catalyzes the epoxidation of olefins, and the novel immobilization of Ru-BINAP, which is active in the enantioselective hy…
A Thomas-Fermi model of a spherical shell of positive charge is investigated, under various boundary conditions. The electron distribution and the ionization charge are given particular attention.
Abstract A method is presented here that allows, in principle, the prediction of the existence and structure of (meta)stable solid compounds. It is based on a set of adjustable modules that are applied to the study of the energy function of the chemical system of interest. The main elements are a set of routines for g…
We have grown Pr0.67Ca0.33MnO3 thin films on LaAlO3 using pulsed laser deposition. Below 50 K, a field induced insulator-metal transition results in changes in resistivity of at least 6 orders of magnitude. The field induced conducting state is metastable at low temperature. The temperature dependence of the resistivi…
We measured the thermodynamic properties for a class of quasi-one-dimensional (1D) molecular magnets with alternating spins and competing nearest- and next-nearest-neighbor exchange interactions. For the two compounds with higher frustration ( $R\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\mathrm{ethyl}$ and $R…
A Monte Carlo simulation model is proposed to study the phase transition and the structural evolution of thermoreversible gels with the coexistence of phase separation and gelation processes. Our model includes the mobility of all the species and the reversibility of bonds of the clusters formed due to cross-linking r…
High quality diamondlike a-C:H has been deposited, at low ion bombardment energies, from an expanding thermal argon/acetylene plasma at high growth rate. It is observed that quality improvement, in terms of hardness, is equivalent to maximization of the refractive index. The highest refractive indices are obtained whe…
Glassy 1-butene (CH2=CHCH2CH3) was studied by incoherent inelastic neutron scattering below 10 meV in the temperature range 18≤T≤80 K covering the glass transition temperature (Tg=60 K). A broad excitation peak due to the low-energy excitation was found at 3–4 meV. The spectra corrected for the Bose factor could be sc…
We demonstrate a fully analytical method for calculations of excited state static and dynamic polarizabilities. From the double residues of a single reference state cubic response function all excited state polarizabilities can be determined. The method forms also a basis for calculations of excited state hyperpolariz…
Resistivity, susceptibility, and specific heat measurements on the new layered superconductors ${\mathrm{Y}}_{2}{\mathrm{C}}_{2}{\mathrm{I}}_{2}$ and ${\mathrm{Y}}_{2}{\mathrm{C}}_{2}{\mathrm{Br}}_{2}$ have been performed to characterize their superconducting state. Our experiments indicate bulk superconductivity with…
A hybrid technique is reported, which combines magnetron sputtering and pulsed laser ablation to produce plasma fluxes intersected on a substrate surface to form metal, ceramic and diamond-like materials. Deposition of crystalline Ti, TixCy, TiCN, and amorphous diamond-like carbon films at low temperatures by the new…
Self-consistent field theory is used to study the phase behavior of melts of semiflexible diblock copolymers. Repulsion between the incompatible blocks leads to microphase separation, while anisotropic external fields and interactions between polymers induce liquid-crystalline phases. Considering symmetric diblocks wi…
Carbon nanotubes have been synthesized by heat treating the polymer at 400 °C in air which was obtained by polyesterification between citric acid and ethylene glycol. Transmission electron micrographs and an electron diffraction pattern showed the formation of carbon nanotubes. The diameter of the tubes ranged from 5…
Results on a lanthanum-modified, lead zirconate-titanate have revealed (1) pressure-induced crossover from normal ferroelectric- (nFE-) to-relaxor (R) behavior; (2) the continuous evolution of the dynamics of the relaxation process; (3) a spontaneous R-to-nFE transition at a temperature well below the dynamic glass te…
A molecular model of network-forming liquids has been formulated in terms of a lattice fluid in which bond formation depends strongly on molecular orientations and local density. The model has been solved in the zeroth- and first-order approximations for molecular and bond geometries similar to water or silica. Result…