Materials Literature
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We have measured the magnetic susceptibilities of single crystals of Cu_{1-x}Zn_xGeO_3 with extremely low Zn concentration (x) lower than x=5x10^{-3} at very low temperatures to investigate the spin-Peierls and antiferromagnetic transitions. The results show that the undoped CuGeO_3 has no antiferromagnetic phase down…
The goal of this work was to design a ferromagnetically coupled Mn(2+)Ni(2+) species. For this, we attempted to combine nitro-nitrito and end-on azido bridges which are both known to be ferromagnetic couplers. This has led us to the compound of formula Mn(N(3))(4)[Ni(en)(2)NO(2)](2) (en = ethylenediamine). The crystal…
The synthesis and characterization of two chiral, redox-active Rh(I) bis(diphenylphosphinite) monomers, complexes 3 and 4, are reported. Complex 4, [(η 2 -1,2- bis(diphenylphosphinite),4-oxo-6-(3‘-α-terthiophene)Rh(I)(η 4 -C 7 H 8 )]BF 4, can be electrochemically polymerized to form poly- 4, and the η 4 -C 7 H 8 ligan…
The reaction between 2 molar equiv of 3-butyrolactone (BL) and either methylalumoxane (MAO) or isobutylalumoxane (IBAO) yielded an adduct, either MAO−BL or IBAO−BL. Both MAO−BL and IBAO−BL were found to be much more effective catalysts for the ring-opening polymerization of the racemic monomer, [ R, S ]-BL, than eithe…
We study the behavior of a semi-infinite monolayer, which is placed initially on a half of an infinite in both directions, ideal crystalline surface, and then evolves in time due to random motion of the monolayer particles. Particles dynamics is modeled as the Kawasaki particle-vacancy exchange process in the presence…
We present Molecular Dynamics (MD), Quasi Harmonic Lattice Dynamics (QHLD) and Energy Minimization (EM) calculations for the crystal structure of Ne, Ar, Kr and Xe as a function of pressure and temperature. New Lennard-Jones (LJ) parameters are obtained for Ne, Kr and Xe to reproduce the experimental pressure dependen…
Abstract Fiberglass piping has typically been prohibited from use in dry deluge fire protection systems and in confined spaces for reasons of flammability, smoke density and toxicity. Advanced resin technology has emerged which breaks through these barriers. The .light weight, corrosion resistance and low maintenance…
The -type cubic compound, , undergoes below a spontaneous magnetic transition at . The magnetic phase diagrams have been determined from the magnetization curves measured on a single crystal in fields up to 10 T. The corresponding magnetic structures have been determined from neutron diffraction studies on the same cr…
Als ferromagnetisch gekoppeltes Spinpentamer wurde das makrocyclische Polyradikal 1 konzipiert. Für diesen Kohlenwasserstoff ergaben Magnetisierungsmessungen einen durchschnittlichen Spin von S = 10 im Grundzustand, was der bislang größten für ein organisches Molekül gemessenen Spinquantenzahl entspricht. Ar = tBuC6H4.
The title compound is not a hexaboride, as was believed for many years. It is therefore not surprising that its structure also contains a novelty: for the first time a pentagonal B7 bipyramid (shown on the right) has been identified as part of the framework of boron atoms in a solid-state compound.
The temperature dependence of the Debye-Waller factors of a 9.4 mol% stabilized cubic ceramic was studied in the range 4-1923 K using neutron powder diffraction. It was found that the data could not be modelled on a harmonic Debye-like model with an additive static disorder component but are significantly anharmonic.…
The porphyrin–surfactant interaction determines the activity of the title catalysts. Amphiphilic porphyrin derivatives (e.g. 1 with M=MnCl, R=CH2CH2(OCH2CH2)2OH) are easy to prepare and can be included in micellar phases.
We study statistical properties of energy spectra of two-dimensional quasiperiodic tight-binding models. Taking into account the symmetries of models defined on various finite approximants of quasiperiodic tilings, we find that the underlying universal level-spacing distribution is given by the Gaussian orthogonal ran…
Resistivity (15 - 710 K), magnetization (80 - 723 K), and calorimetric (200 - 623 K) measurements on have shown evidence for the formation of Jahn - Teller (JT) polarons below . Above 560 K, activated conduction with is observed and shows Curie - Weiss behaviour. Over the temperature range 270 - 340 K, the conductivit…
Model compounds for silica surfaces modified with metal complexes are provided by the mononuclear anionic diperoxo species 1 and the dinuclear complex anions 2 (M = Mo, W). They were obtained in fair to nearly quantitative yields by the reactions of Ph3SiOH and [Ph2Si(OH)]2O, respectively, with an aqueous solution of…
We report an ellipsometry study of the wetting of hexane on water. By adding salt to the water, we are able to tune the Hamaker constant of this system. This allows us to demonstrate, for the first time, that two rather than one wetting transitions can exist in a single system. Upon increasing the temperature, a disco…
The cold-cathode electron emission properties of amorphous tetrahedral diamondlike carbon are promising for flat-panel display and vacuum microelectronics technologies. The onset of electron emission is, typically, preceded by “conditioning” where the material is stressed by an applied electric field. To simulate cond…
Nonscattering glasses that are indefinitely stable with respect to crystallization can be prepared from the title compounds. In these solid solutions, the dendritic substituents effectively suppress interactions between the phthalocyanine units (see the structure depicted on the right).
The ruffle of the porphyrin increases with the number of meso substituents. (Octaethylporphyrin)nickel(II) undergoes nucleophilic substitution reactions upon treatment with alkylating reagents such as butyllithium, hydrolysis with water, and oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone [DDQ; Eq. (a)]. Alky…
We report a principle that allows one to write visible light emitting silicon patterns of arbitrary shape down to the submicrometer scale. We demonstrate that porous Si growth can electrochemically be initiated preferentially at surface defects created in an $n$-type Si substrate by ${\mathrm{Si}}^{++}$ focused ion be…