Materials Literature
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T-shaped polyphilic triblock molecules, consisting of a rodlike p-terphenyl unit, a hydrophilic and flexible laterally attached oligo(oxyethylene) chain terminated by an 1-acylamino-1-deoxy-D-sorbitol unit, and two end-attached lipophilic alkyl chains, have been synthesized by palladium-catalyzed cross-coupling reacti…
We report novel thermosensitive hybrid core-shell particles via in situ gold nanoparticle formation using thermosensitive core-shell particles as a template. This method for the in situ synthesis of gold nanoparticles with microgel interiors offers the advantage of eliminating or significantly reducing particle aggreg…
Y3Al5O12:Ce3+ (YAG:Ce3+) nanocrystals were synthesized in 1,4-butylene glycol (BG) with and without poly(ethylene glycol) (PEG) by the glycothermal method. The internal quantum efficiency of the photoluminescence (PL) corresponding to the 5d --> 4f transition of Ce3+ in the YAG:Ce3+ nanocrystal increased from 21.3 to…
Well-aligned, high-purity carbon nanotube (CNT) stacks of up to 10 layers fabricated in one batch process have been formed by water-assisted selective etching of carbon atoms. Etching takes place at the CNT caps as well as at the interface between CNTs and metal catalyst particles. This simple process generates high-p…
Size-controlled synthesis of nanoparticles of less than a few nanometers in size is a challenge due to the spatial resolution limit of most scattering and imaging techniques used for their structural characterization. We present the self-consistent analysis of the extended x-ray absorption fine-structure (EXAFS) spect…
We present here a formulation for the calculation of the configuration averaged lattice thermal conductivity in random alloys. Our formulation is based on the augmented-space theorem, introduced by one of us, combined with a generalized diagrammatic technique. The diagrammatic approach simplifies the problem of includ…
We report results of molecular dynamics simulation of shock wave propagation in silicon in [100], [110], and [111] directions obtained using a classical environment-dependent interatomic potential (EDIP). Several regimes of materials response are classified as a function of shock wave intensity using the calculated sh…
We construct a spin-drift-diffusion model to describe spin-polarized electron transport in zincblende semiconductors in the presence of magnetic fields, electric fields, and off-diagonal strain. We present predictions of the model for geometries that correspond to optical spin injection from the absorption of circular…
The induced motion of a magnetic vortex in a micron-sized ferromagnetic disk due to the DC current injection is studied by measuring planar Hall effect. The DC current injection is found to induce the spin torque that sweeps the vortex out of the disk at the critical current while bias magnetic field are applied. The…
Shear stresses are the driving forces for the creation of both point and extended defects in crystals subjected to high pressures and temperatures. Recently, we observed anomalous elastic materials response in shock-compressed silicon and diamond in the course of our MD simulations and were able to relate this phenome…
Atomistic pseudopotential plus configuration interaction calculations of the energy needed to charge dots by either electrons or holes are described, and contrasted with the widely used, but highly simplified two-dimensional parabolic effective mass approximation (2D-EMA). Substantial discrepancies are found, especial…
We have simulated the non-linear dynamics of networks of spin-transfer oscillators. The oscillators are magnetically uncoupled but electrically connected in series. We use a modified Landau-Lifschitz- Gilbert equation to describe the motion of each oscillator in the presence of the oscillations of all the others. We s…
Ultra‐thin fibers of zinc oxide (ZnO) were prepared by sol–gel processing and the electrospinning technique using poly(vinyl acetate) and zinc acetate as precursors. The fibers were characterized by thermogravimetric analysis, scanning electron microscopy, Fourier‐transfer infrared, and X‐ray diffraction, respectively…
Low temperature properties of ${\mathrm{BaZrO}}_{3}$ are revealed by combining experimental techniques (x-ray diffraction, neutron scattering and dielectric measurements) with theoretical first-principles-based methods (total energy and linear response calculations within density functional theory, and effective Hamil…
We report an in situ observation of water condensation and evaporation on lotus leaf surfaces inside an environmental scanning electron microscope. The real-time observation shows, at the micrometer length scale, how water drops grow to large contact angles during water condensation, and decrease in size and contact a…
Aluminum hydride polymorphs (alpha-AlH3, beta-AlH3, and gamma-AlH3) were prepared by organometallic synthesis. Hydrogen capacities approaching 10 wt % at desorption temperatures less than 100 degrees C have been demonstrated with freshly prepared AlH3. The temperature-dependent rate constants were determined by measur…
We calculate the magnetic interactions between two nearest neighbor substitutional magnetic ions (Co or Mn) in ZnO by means of density functional theory and compare it with the available experimental data. Using the local spin density approximation we find a coexistence of ferro- and antiferromagnetic couplings for Zn…
We theoretically demonstrate that at a finite temperature, an effective wall thickness of a single walled carbon nanotube (SWNT) should be $W=W_s+W_d$, where $W_s$ is the static thickness defined as the extension of the outmost electronic orbit and $W_d$ the dynamic thickness due to thermal vibration of atoms. Both mo…
Artificially fabricated structures with periodically modulated parameters such as photonic crystals offer novel ways of controlling the flow of light due to the existence of a range of forbidden frequencies associated with a photonic band gap. It is believed that modulation of the refractive index in all three spatial…
We study the presence of ferromagnetism in the phase diagram of the two-dimensional honeycomb lattice close to half-filling (graphene) as a function of the strength of the Coulomb interaction and doping. We show that exchange interactions between Dirac fermions can stabilize a ferromagnetic phase at low doping when th…