Materials Literature
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When two chemically passivated solids are brought into contact, interfacial interactions between the solids compete with intrabulk elastic forces. The relative importance of these interactions, which are length-scale dependent, will be estimated using scaling arguments. If elastic interactions dominate on all length s…
We present a theoretical study of the optical absorption spectrum of small boron-nitride and carbon nanotubes using time-dependent density-functional theory and the random phase approximation. Both for C and BN tubes, the absorption of light polarized perpendicular to the tube-axis is strongly suppressed due to local…
Magnetism of a misfit layered cobaltite [Ca$_2$Co$_{4/3}$Cu$_{2/3}$O$_4$]$_x^{\rm RS}$[CoO$_2$] ($x \sim$ 0.62, RS denotes a rocksalt-type block) was investigated by a positive muon spin rotation and relaxation ($μ^+$SR) experiment. A transition to an incommensurate ({\sf IC}) spin density wave ({\sf SDW}) state was f…
Amorphous SiO2 (a-SiO2), such as bulk silica glasses and thin films has been one of the key materials in modern optoelectronic industries. These materials are currently used in communication technologies as optical fibers, thin films for electrical insulation in dynamic random access memories (DRAM), and optical lense…
Phase transformation and crystal growth in nanoparticles may happen via mechanisms distinct from those in bulk materials. We combine experimental studies of as-synthesized and hydrothermally coarsened titania (TiO 2 ) and zinc sulfide (ZnS) with thermodynamic analysis, kinetic modeling and molecular dynamics (MD) simu…
A new method of measuring long spin-lattice relaxation times ($T_1$) is proposed. Being a single scan technique, the method is at least one order of magnitude faster than the conventional technique. This method (Single-Scan or Slice Selected Inversion Recovery or SSIR) relies on the slice selection technique. The meth…
Diluted magnetic semiconductor Zn1−xMnxO nanowires were synthesized via an in situ doping of manganese in ZnO nanowires using vapor phase growth at 500 °C. The maximum content of the manganese in the ZnO is around 13 at. %, approaching the maximum thermal equilibrium limit of Mn solubility in ZnO at the growth tempera…
Ferroelectric BiFeO3 thin films have been prepared on Pt/TiO2/SiO2/Si substrates in various oxygen pressures of 0.001–0.1 Torr at a temperature as low as 450 °C by pulsed-laser deposition. The crystallinity of the films was studied by x-ray diffraction. X-ray photoelectron spectroscopy showed that the films have a sin…
Nanocomposites α-Fe/Fe3B/Y2O3 were prepared by a melt-spun technique, and the electromagnetic wave absorption properties were measured in the 0.05–20.05 GHz range. Compared with α-Fe/Y2O3 composites, the resonance frequency (fr) of α-Fe/Fe3B/Y2O3 shifted to a higher frequency range due to the large anisotropy field (H…
In this contribution, we report the successful preparation of supported metal catalysts using dendrimer-encapsulated Pt nanoparticles as metal precursors. Polyamidoamine (PAMAM) dendrimers were first used to template and stabilize Pt nanoparticles prepared in solution. These dendrimer-encapsulated nanoparticles were t…
We report the use of carbon nanotubes as a sensor for chemical nerve agents. Thin-film transistors constructed from random networks of single-walled carbon nanotubes were used to detect dimethyl methylphosphonate (DMMP), a simulant for the nerve agent sarin. These sensors are reversible and capable of detecting DMMP a…
Abstract A coagulation method providing a better dispersion of single‐walled carbon nanotubes (SWNTs) in a polymer matrix was used to produce SWNT/poly(methyl methacrylate) (PMMA) composites. Optical microscopy and scanning electron microscopy showed an improved dispersion of SWNTs in the PMMA matrix, a key factor in…
Carbon doped oxide dielectrics comprised of Si, C, O, and H (SiCOH) have been prepared by plasma enhanced chemical vapor deposition (PECVD) from mixtures of tetramethylcyclotetrasiloxane (TMCTS) and an organic precursor. The films have been analyzed by determining their elemental composition and by Fourier transform i…
X-ray and neutron-diffraction, dc magnetic susceptibility, magnetization, and specific-heat measurements are reported for ${\mathrm{F}\mathrm{e}}_{x}{\mathrm{C}\mathrm{o}}_{1\ensuremath{-}x}{\mathrm{T}\mathrm{a}}_{2}{\mathrm{O}}_{6}$ mixed oxides. X-ray refinement indicates homogeneous samples for all the reported con…
We study from first-principles ${\mathrm{Ca}}_{2}{\mathrm{MgSi}}_{2}{\mathrm{O}}_{7}$ \aa{}kermanite within the local density approximation (LDA) of the density-functional theory. The electronic band structure is formed by weakly dispersive bands, with a 4.2 eV LDA gap. We report the crystal structure, dielectric prop…
The cluster (Cu8(mu8-Se)[S2P(OEt)2]6)0.54(Cu6[S2P(OEt)2]6)0.46 (2) was prepared in 78% yield from the reaction of Cu8(Se)[Se2P(OPr)2]6 (1) and NH4S2P(OEt)2 in toluene. The central selenide ion in 2 was characterized by 77Se NMR at delta -976 ppm. The simulated solid-state 31P NMR spectrum shows two components with an…
For powder samples of polynuclear metal complexes the dependence of the inelastic neutron scattering intensity on the momentum transfer Q is known to be described by a combination of so-called interference terms. They reflect the interplay between the geometrical structure of the compound and the spatial properties of…
A novel gas-phase procedure for the control of amino group density on porous silica through consecutive reactions of aminopropylalkoxysilanes and water vapor was developed. First heat-treated silica was saturated with trifunctional γ-aminopropyltrimethoxysilane (APTMS) or γ-aminopropyltriethoxysilane (APTS) in an atom…
A new and feasible method to prepare long and well-oriented SWNTs on substrates in large scale is developed by applying a floating catalyst chemical vapor deposition (CVD) process. The catalysts for SWNT growth come from the decomposition of iron pentacarbonyl (Fe(CO) 5 ) formed in situ from the reaction of iron powde…
We report on the low-temperature magnetic susceptibilities and specific heats of the isostructural spin-ladder molecular complexes ${L}_{2}[M(\mathrm{opba}){]}_{3}\ensuremath{\cdot}x\mathrm{DMSO}\ensuremath{\cdot}y{\mathrm{H}}_{2}\mathrm{O},$ hereafter abbreviated by ${L}_{2}{M}_{3}$ (where $L$=La, Gd, Tb, Dy, Ho and…