Materials Literature
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Exciton characteristics of GaTe single crystals grown by vapor-phase transport were studied by optical measurements. A hydrogenlike exciton series up to $n=4$ was clearly observed in the absorption spectra at 2 K. In the $n=1$ exciton energy region three types of exciton lines were found. By analyzing microphotolumine…
The control of biodegradation and the improvement of moldability of poly- l -lactide, PLA, have been difficult because of the high crystallinity and the lability of melt viscosity. The synthesis of biodegradable PLA having the branched structure, comb-type PLA, was carried out by using only metabolizable materials to…
The mechanism of the B3/B1 phase transition of SiC has been investigated by periodic LCAO-DFT least-enthalpy calculations. A new transformation pathway, based on a Pmm2 orthorhombic intermediate state with two SiC units per cell, is found to be energetically favored over the traditional R3m mechanism. The computed act…
Time-resolved X-ray diffraction is utilized to follow phase transitions in nanostructured silica/surfactant composites in real time under hydrothermal conditions. The data allow us both to obtain kinetic parameters and to observe intermediate phases. In all cases, changes in the packing of the organic component of the…
Solid-state electrochemical cells based on oxygen-ion conduction (pure ionic or mixed ionic/electronic conductors) allow selective transport of oxygen (oxygen-ion conducting materials) in the form of ionic flux at high temperatures. Thus these systems can act as filters for molecular oxygen and can be used for both ge…
The merger of density-functional theory in the local density approximation (LDA) and many-body dynamical mean field theory (DMFT) allows for an ab initio calculation of Ce including the inherent 4f electronic correlations. We solve the DMFT equations by the quantum Monte Carlo (QMC) technique and calculate the Ce ener…
We report self-consistent {\it ab initio} calculations of structural and electronic properties for the B- and Mg-terminated MgB$_{2}$ (0001) surfaces. We employ ultra-soft pseudopotentials and plane wave basis sets within the generalized gradient approximation. The surface relaxations are found to be small for both B-…
An unusual quasi-two-dimensional heavy band mass van Hove singularity (vHs) lies very near the Fermi energy in MgCNi3, recently reported to superconduct at 8.5 K. This compound is strongly exchange enhanced and is unstable to ferromagnetism upon hole doping with 12% Mg --> Na or Li. The 1/4-depleted fcc (frustrated) N…
We report measurements on MgB2 up to ~40GPa. Increasing pressure yields a monotonous decrease of the lattice parameters and of the c/a ratio, but no structural transition down to parameters smaller than those of AlB2. The transition superconducting temperature also decreases with temperature in a sample dependent way.…
We investigate the equilibrium properties of arrays of coherent strained islands in heteroepitaxial thin films of bidimensional materials. The model we use takes into account only three essential ingredients : surface energies, elastic energies of the film and of the substrate and interaction energies between islands…
The scaling properties of the maximal height of a growing self-affine surface with a lateral extent $L$ are considered. In the late-time regime its value measured relative to the evolving average height scales like the roughness: $h^{*}_{L} \sim L^α$. For large values its distribution obeys $\log{P(h^{*}_{L})} \sim -A…
In the first part of the paper we show that the constraining potentials introduced to mimic entanglement effects in Edwards' tube model and Flory's constrained junction model are diagonal in the generalized Rouse modes of the corresponding phantom network. As a consequence, both models can formally be solved exactly f…
We analyze the combined effect of the long range Coulomb (LRC) interaction and of surface energy on first order density-driven phase transitions in the presence of a compensating rigid background. We study mixed states formed by regions of one phase surrounded by the other in the case in which the scale of the inhomog…
The interplay between the broken symmetry and the boundary conditions alters profoundly the electronic properties of carbon single-wall nanotubes (SWNTs) of finite-lengths. For SWNTs $(p,q)$ characterized by $p=k+l,$ $q=k\ensuremath{-}l,$ $0<~l<~k,$ and $k=1,2,\dots{},$ the energy gaps for finite SWNTs belonging…
The synthesis and characterization of complex dendritic, rigid rod poly-2,7-fluorene homopolymers and copolymers via a macromonomer approach is reported. Several 2,7-dibromofluorene monomers containing benzyl ether dendrons (generations 1, 2, and 3) in the 9,9'-position of the fluorene ring were prepared and employed…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTElectrodeposition of Ordered Bi2Te3 Nanowire ArraysAmy L. Prieto, Melissa S. Sander, Marisol S. Martín-González, Ronald Gronsky, Timothy Sands, and Angelica M. StacyView Author Information Department of Chemistry University of California, Berkeley Berkeley, California…
Certain microporous carbons have pores of molecular dimensions, the size of which can be adjusted over a wide range to fit the dimensions of a large variety of molecules. With knowing the dimensions of these molecules, size-calibrated porous carbons can be produced. In this work, we took advantage of the electronic co…
Abstract A general approach, based on the polymer reference interaction site model (PRISM) integral equation theory, suitable for characterizing arbitrarily complex polyolefin melts is described. We tested the method by calculating the melt structures of linear polyethylene (PE) and isotactic polypropylene (iPP) and t…
Smectic blue phases (BP(sm)) are original physical systems of thermotropic liquid crystals, displaying a double geometrical frustration: the extension of chirality in the three spatial dimensions, such as classical blue phases, and the competition between smectic order and helical twist, such as twist grain boundary (…
[structure: see text] Acid-catalyzed [2 + 2] condensation reactions of polycyclic aromatic vicinal diketones including aceanthrenequinone, phenathrenequinone, and pyrene-4,5-dione with 5-mesityldipyrromethanes are outlined, and this methodology provides a flexible entry to spiro-tricyclic porphodimethenes. The porphod…