Materials Literature
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A series of alpha,omega-donor-substituted distyrylbenzene dimers held together by the [2.2]paracyclophane core were designed, synthesized, and characterized. Different substituents were chosen to modulate the strength of the donor nitrogen groups and to allow the molecules to be either neutral and soluble in nonpolar…
We have carried out a series of ab initio calculations to investigate changes in the optical properties of Si quantum dots as a function of surface passivation. In particular, we have compared hydrogen-passivated dots with those having alkyl groups at the surface. We find that, while on clusters with reconstructed sur…
Thin films of the intercalated organic−inorganic hybrids (PPy) x MoO 3 (PPy: polypyrrole) have been prepared by an ex-situ intercalation process. The host MoO 3 films were first deposited on LaAlO 3 (LAO) single-crystal substrates by using a CVD method followed by the intercalation of PPy into the MoO 3 films. The pre…
A pH-responsive volume-change function was successfully introduced into a supramolecular hydrogel that contained GalNAc-appended (GalNAc=N-acetylgalactosamine) glutamate ester 1 by the simple mixing of it with an appropriate amount of 2 a or 2 b amphiphilic carboxylic acid. In the 1:1 mixture (1:2), the hydrogel swell…
Configurational states that are to be associated, according to Goldstein, with the basins in the potential energy landscape cannot be characterized by any particular basin identifier such as the basin minima, the lowest barrier, the most probable energy barrier, etc. since the basin free energy turns out to be indepen…
We report low-temperature electrical transport studies of molecule-scale silicon nanowires. Individual nanowires exhibit well-defined Coulomb blockade oscillations characteristic of charge addition to a single nanostructure with length scales up to at least 400 nm. Further studies demonstrate coherent charge transport…
Using X-ray scattering and the technique of multiple diffreactions, we revisit the dynamical transition of charge density waves (CDWs) in K0.3MoO3 under applied voltages. In addition to the usual transport and half width (of Bragg peaks) measurements, we also measure the triplet phase by three-wave diffraction, which…
The connection of lipophilic gallic acid derivatives at the 5,5'- or 6,6'-positions of the rigid 2,6-bis(1-ethyl-benzimidazol-2-yl)pyridine core provides two pro-mesogenic tridentate ligands L10 and L12, whose molecular shapes, anisometries, and directional intermolecular pi-stacking can be tuned. X-ray diffraction da…
We derive within the dielectric-continuum model an integral equation that defines interface and confined polar optical-phonon modes in nanocrystals with a wurtzite crystal structure. It is demonstrated theoretically that, while the frequency of confined polar optical phonons in zinc-blende nanocrystals is equal to tha…
A solvent-free mechanochemical route for the synthesis of polyaniline has been developed. Reactions between anilinium salts, such as anilinium chloride, anilinium sulfate, and anilinium camphorsulfonic acid and the oxidant, ammonium peroxydisulfate, result in polyaniline formation on ball-milling the reactants. Spectr…
Abstract A critical review is provided of the principles guiding the synthesis of meso‐ and macroporous metal oxides on multiple length scales in the presence of surfactant mesophases and colloidal arrays of monodisperse spheres, and correlations between the synthesis conditions and the properties of the resulting mes…
A giant low-frequency, in-plane dielectric constant, ϵ∼106, for epitaxial thin films of Ca1−xLaxMnO3 (x⩽0.03) was observed over a broad temperature range, 4K⩽T⩽300K. This phenomenon is attributed to an internal barrier-layer capacitor (IBLC) structure, with Schottky contacts between semiconducting grains. The room-tem…
Measurements of the low-frequency $(f\ensuremath{\leqslant}100\phantom{\rule{0.3em}{0ex}}\mathrm{kHz})$ permittivity $(\ensuremath{\epsilon})$ and conductivity $(\ensuremath{\sigma})$ at $T\ensuremath{\lesssim}150\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ are reported for ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}…
It is demonstrated by SQUID measurements that (Ga,Mn)As films can exhibit perpendicular easy axis at low temperatures, even under compressive strain, provided that the hole concentration is sufficiently low. In such films, the easy axis assumes a standard in-plane orientation when the temperature is raised towards the…
Making contact: The hydrophobicity of the top layer of a multilayer thin film composed of polyelectrolytes and clay nanorods determines the contact angle of a water drop on the surface (see picture). The film is built up layer-by-layer on a silicon surface, thus enabling the surface properties to be readily modified b…
We introduce the concept of stationary metastable states (SMS's) in the presence of another more stable state. The stationary nature allows us to study SMS's by using a restricted partition function formalism as advocated by Penrose and Lebowitz and requires continuing the free energy. The formalism ensures that SMS f…
Several levels of theory, including both Gaussian-based and plane wave density functional theory (DFT), second-order perturbation theory (MP2), and coupled cluster methods (CCSD(T)), are employed to study Au6 and Au8 clusters. All methods predict that the lowest energy isomer of Au6 is planar. For Au8, both DFT method…
The synthesis and characterization of 1-3-nm diameter, structurally well-defined, bimetallic AuAg dendrimer-encapsulated nanoparticles (DENs) are reported. Three different bimetallic structures were examined: AuAg alloys synthesized by cocomplexation and subsequent reduction of dendrimer-encapsulated Au3+ and Ag+ and…
We have found a remarkable increase (up to 60%) of the dielectric constant with the onset of magnetic order at $42\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in the metastable orthorhombic structures of $\mathrm{Y}\mathrm{Mn}{\mathrm{O}}_{3}$ and $\mathrm{Ho}\mathrm{Mn}{\mathrm{O}}_{3}$ that proves the existence of a stron…
Controlling fabrication of mono-dispersed and well-aligned arrays of one-dimensional (1D) nanostructures, nanowires or nanotubes, will benefit a lot for the investigation of their physical properties and their potential use in nanolasers, chemical and biological sensors, and nanoelectrode arrays for solar energy conve…