Materials Literature
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We study how the ferroelastic domain structure sets in in an epitaxial film of a material with second order proper ferroelastic transition. The domain structures considered are similar to either $a_{1}/a_{2}/a_{1}/a_{2}$ or $c/a/c/a$ structures in perovskite ferroelectrics. If the "extrinsic" misfit strain, not associ…
In order to understand the unexpected superconducting behavior of MgB$_2$ compound we have made electronic structure calculations for MgB$_2$ and closely related systems. Our calculated Debye temperature from the elastic properties indicate that the average phonon frequency is very large in MgB$_2$ compared with other…
We review the search for the glass transition in water in its various amorphous forms, and highlight the paradoxes that the search has produced. Focussing on the glassy form of water obtained by hyperquenching, we examine its reported calorimetric properties in the light of new findings for bulk glassformers vitrified…
The determination of the structure of transient molecules, such as photoexcited states, in disordered media (such as in solution) usually requires methods with high temporal resolution. The transient molecular structure of a reaction intermediate produced by photoexcitation of NiTPP-L2 (NiTPP, nickeltetraphenylporphyr…
A series of photophysical measurements and semiempirical calculations were carried out with 1,4-bis(phenylethynyl)benzene in search of evidence on the effects of phenyl group rotation and chromophore aggregation of oligo- and poly(phenyleneethynylene)s. It is suggested that planarization gives rise to relatively modes…
PMMA-layered silicate nanocomposites were prepared by in-situ suspension polymerization and emulsion polymerization. For the suspension polymerization, the silicate layers were dispersed individually in water, and we speculate that they are adsorbed on the surface of monomer droplets. For the emulsion polymerization,…
Crystallization of concentrated colloidal suspensions was studied in real space with laser scanning confocal microscopy. Direct imaging in three dimensions allowed identification and observation of both nucleation and growth of crystalline regions, providing an experimental measure of properties of the nucleating crys…
A well cleaned copper plate with a thin Au layer deposited was heated in air to make hole transfer sites with p-Cu 2 O at 800 °C for 3 min. A transparent NiO layer was prepared on the surface of this device to make electron transfer sites on the surface. This heat-treated device, having 2 µm Au layers, exhibited a rem…
Metalation of C6H6 has been known for a long time as a side reaction occurring in refluxing benzene solutions of Rh2(CO)4(TPP) (TTP = tetraphenylporphyrin). Rather than representing the intrinsic reactivity of this complex, such hydrocarbon activation proceeds via RhII(por) and RhIII(por) derivatives resulting from ox…
The widths of the peaks in the pair distribution function (PDF) contain information on the phonons of a material. At large interatomic distances r the width of the peaks is fully determined by the thermal parameters. For low r, however, correlation effects reduce the width significantly, depending on the shape of the…
Intrinsic, extrinsic (transition metals and hydroxyl), and induced (color centers) absorption of multicomponent silicate glasses in UV, visible and near IR spectral regions are described. Parasitic effects influencing absorption measurements are discussed. Excitation to the intrinsic absorption band results in intrins…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSolid-Phase Synthesis and Asymmetric Reactions of Polymer-Supported Highly Enantioenriched AllylsilanesMichinori Suginome, Taisuke Iwanami, and Yoshihiko ItoView Author Information Department of Synthetic Chemistry and Biological Chemistry Graduate School of Engineerin…
A spectroscopic study of the initial stage of the Ti(OPr i ) 4 sol−gel process has been carried out. We have observed that the primary hydrolysis/condensation reaction is complete at low water concentration. At times shorter that the induction time, the reaction results in creation of nanosize nuclei. The most importa…
We study the dynamics of a glassy model with infinite range interactions externally driven by an oscillatory force. We find a well-defined transition in the (temperature-amplitude-frequency) phase diagram between (i) a "glassy" state characterized by the slow relaxation of one-time quantities, aging in two-time quanti…
The electronic ground state and structural and magnetic properties of the pyrite-type antiferromagnetic semiconductor ${\mathrm{MnTe}}_{2}$ have been investigated by combining ${}^{12}\mathrm{Te}$ M\"ossbauer spectroscopy and x-ray-diffraction and electrical resistance measurements at pressures up to 22.5 GPa and temp…
${\mathrm{LaTiO}}_{3.5}$ is a layered compound made up of four ${\mathrm{LaTiO}}_{3}$ units: two regular perovskite units stacked between two distorted units that share an additional oxygen layer. In a single-crystalline thin film the (100) plane can be aligned parallel to the substrate surface, i.e., the additional o…
Density-functional calculations of electronic and magnetic properties of the spinel compound ${\mathrm{ZnFe}}_{2}{\mathrm{O}}_{4}$ done with the general potential linearized augmented plane-wave method are reported. We find significant differences between local spin-density approximation and generalized gradient appro…
Four europium group XIV chalcogenides have been synthesized using the reactive flux method: K(2)EuTSe(5) (I, II) and KEuTS(4) (III, IV) where T = Si, Ge. K(2)EuSiSe(5), I, crystallizes in the monoclinic space group P2(1)/c with cell parameters a = 11.669(3) A, b = 9.844(2) A, c = 8.917(2) A, beta = 91.583(5) degrees,…
During the drying of many polymer films, temperature and compositional changes induce a rubbery−glassy transition at the film surface. The transition front propagates toward the substrate as drying proceeds, eventually rendering the entire coating glassy. The glass transition induces structural changes that have a dir…
Extracting reliable reaction kinetics from nonisothermal calorimetric results can be difficult. The reaction model, activation energy, and frequency factor make up a “kinetic triplet” for a particular reaction and define the reaction kinetics. One expects a good correlation between data and the predictions of the reac…