Materials Literature
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Colloidal dispersions of Mg/Al LDH platelets show liquid-crystal phase at a certain particle concentration. Threaded texture observed with polarized microscopy indicated it was typical of a nematic phase, which can often be found in traditional liquid crystals.
Various vacancy-impurity complexes that are believed to account for the deactivation of As in highly n-doped silicon are investigated using the density functional theory. The electronic structure and defect levels of these impurities are determined, both of which are crucial for the understanding and modeling of the d…
The viability of 1,3-dipolar cycloadditions of a series of 1,3-dipolar molecules (azomethine ylide, ozone, nitrone, nitrile imine, nitrile ylide, nitrile oxide, diazomethane, and methyl azide) onto the sidewalls of carbon nanotubes has been assessed theoretically by means of a two-layered ONIOM approach. The theoretic…
We have carried out a direct measurement of the degree of spin polarization ($\mathbit{P}$) of the magnetic semiconductor ${\mathrm{G}\mathrm{a}}_{1\ensuremath{-}x}{\mathrm{M}\mathrm{n}}_{x}\mathrm{A}\mathrm{s}$ using Andreev reflection spectroscopy. Analyses of the conductance spectra of high transparency ${\mathrm{G…
Electrochemical potential dependence of Raman intensity of isolated single-walled carbon nanotubes (SWNT) on gold electrode in aqueous solution was investigated employing in situ resonant confocal micro Raman spectroscopy. Absolute potential of the Fermi level of individual tubes was estimated from the potential depen…
The generation of nanoscale interconnects and supramolecular, hierarchical assemblies enables the development of a number of novel nanoscale applications. A rational approach toward engineering a robust system is through chemical recognition. Here, we show the in situ mineralization of crystalline CdTe quantum dots on…
Metallic nanowires of cobalt, copper, and iron oxide magnetite (Fe 3 O 4 ) have been synthesized within the pores of mesoporous silica using a supercritical fluid inclusion technique. The mesoporous matrix provides a means of producing a high density of stable, hexagonally ordered arrays of highly crystalline nanowire…
We have developed a model to predict the chemical reactivity of carbon nanotubes (CNTs) quantitatively from their initial structures. The parameters, universal for each reaction, of the model can be obtained from a graphene sheet analysis. The chemical reactivity of hydrogenation, hydroxylation, and fluorination were…
ZnO films were prepared on Si(100) substrates using rf magnetron sputtering and the correlations between the growth conditions and the resultant film properties were discussed. The intensity of the visible emission related with intrinsic defects in ZnO film was dramatically suppressed by increasing the O 2 /Ar+O 2 rat…
The electromagnetic (EM) wave absorption properties in the gigahertz region (12–110 GHz) of carbon microcoils (CMCs) with a three-dimensional-helical/spiral chiral structure (1–10 μm coil diameter and 0.1–10 mm coil length) were examined using the open space method. It was found that the target value of reflection los…
The three novel, multi-nickel-substituted heteropolytungstates [Ni(6)As(3)W(24)O(94)(H(2)O)(2)](17)(-) (1), [Ni(3)Na(H(2)O)(2)(AsW(9)O(34))(2)](11)(-) (2), and [Ni(4)Mn(2)P(3)W(24)O(94)(H(2)O)(2)](17)(-) (3) have been synthesized and characterized by IR, elemental analysis, electrochemistry, and magnetic studies. Sing…
Electronic transport through thin and laterally constrained domain walls in ferromagnetic nanojunctions is analyzed theoretically. The description is formulated in the basis of scattering states. The resistance of the domain wall is calculated in the regime of strong electron reflection from the wall. It is shown that…
${\mathrm{K}}_{1\ensuremath{-}x}{\mathrm{Li}}_{x}{\mathrm{TaO}}_{3}$ (KLT) solid solutions exhibit a variety of interesting physical phenomena related to large displacements of Li-ions from ideal perovskite A-site positions. First-principles calculations for KLT supercells were used to investigate these phenomena. Lat…
Excited-state relaxations in molecules are responsible for a redshift of the absorption peak with respect to the emission peak (Franck-Condon shift). The magnitude of this shift in semiconductor quantum dots is still unknown. Here we report first-principle calculations of excited-state relaxations in small (diameter $…
Recent reports have shown enhanced fluorescence for fluorophores in close proximity to chemically deposited silver islands or colloids. To expand the usefulness of metal-enhanced fluorescence we tested fractal silver structures formed on, or near, silver electrodes by passage of electric currents. The emission intensi…
A ferromagnetic semiconductor, rutile (Ti,Co)O2, exhibits anomalous Hall effect at room temperature. Strong dependence of the anomalous Hall effect, as well as the magneto-optic response, on the carrier concentration suggests carrier induced ferromagnetism in this compound. Both ferromagnetic responses are caused by t…
Here we employ both Fe K and L2,3 edge x-ray absorption near-edge structure (XANES) spectroscopy techniques to clarify that iron in the B-site ordered double-perovskite halfmetal, Sr2FeMoO6.0, possesses a mixed-valence state, FeII/III, and accordingly molybdenum a mixed MoV/VI valence state. A reliable interpretation…
In this paper, we describe the synthesis of tailormade cobalt and manganese oxides by a two-step preparation method. The first step consists of precipitating metal alkoxide powders from aliphatic polyalcohol solutions of salts. Their particle size, composition, and morphology can be independently tuned by controlling…
We analyze the energetics of spherelike micellar phases in diblock copolymers in terms of well-studied, geometric quantities for their lattices. We argue that the A15 lattice with Pm3;n symmetry should be favored as the blocks become more symmetric and corroborate this through a self-consistent field theory. Because p…
Auger rates are calculated for CdSe colloidal quantum dots using atomistic empirical pseudopotential wave functions. We predict the dependence of Auger electron cooling on size, on correlation effects (included via configuration interaction), and on the presence of a spectator exciton. Auger multiexciton recombination…