Materials Literature
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We propose ${\mathrm{Si}}_{x}{\mathrm{Ge}}_{1\ensuremath{-}x}$ alloys as suitable candidates for spintronic applications. Remarkably, our first-principles investigation explains, within the local spin density approximation, the microscopic mechanism that stabilizes the half metallicity in Si matrices under Ge alloying…
In order to explore the large shear-strain-induced polymorph, α-Ti3GeC2 polycrystals were investigated by using a synchrotron radiation source to 64GPa under nonhydrostatic state. Upon compression to 26.6GPa, α-Ti3GeC2 starts to transform to β-Ti3GeC2. As compared to α-Ti3GeC2, the cell parameter a of β-Ti3GeC2 is sli…
Na K-edge X ray absorption near-edge structure (XANES) spectra for minerals and glasses were collected using synchrotron radiation. Na-K XANES is a good structural probe to determine the coordination state of this element in important minerals and glasses. From the XANES spectra on crystalline reference phases with di…
We report on the mechanism of photodegradation of porous silicon luminescence in ambient containing molecular oxygen. Energy transfer from excitons confined in silicon nanocrystallites to molecular oxygen results in the generation of highly chemically reactive singlet oxygen molecules. The subsequent interaction of si…
Dual-frequency addressed hybrid-aligned nematic (HAN) liquid crystal cell is demonstrated as a variable optical attenuator at 1.55μm wavelength. By controlling the low- and high-frequency electric field, the dual-frequency liquid crystal (DFLC) molecules can be reoriented parallel or perpendicular to the substrates so…
The performance of a VO2 thin-film microbolometer has been investigated. The device is operated within 35°C<T<60°C, in the hysteretic metal-insulator transition region. An algebraic hysteresis model has been used to model the resistance-temperature characteristic of the sensor. It accurately describes th…
We used a time-of-flight method to study the charge carrier mobility properties of a molecular-aligned discotic liquid crystal semiconductor based on Cu-phthalocyanine. The heated isotropic-phase semiconductor material was sandwiched between transparent electrodes coated onto glass substrates without conventional alig…
A novel process for wrapping individual myoglobin molecules with an ultrathin shell of silica is reported. Confinement of single protein molecules in microemulsion water droplets followed by the controlled hydrolysis and condensation of tetramethoxysilane at the oil/water interface produces discrete protein/ silica na…
The effect of nitride passivation on the visible photoluminescence from nanocrystal Si (nc-Si) is investigated. Silicon-rich silicon nitride (SRSN) and silicon-rich silicon oxide (SRSO), which consist of nc-Si embedded in silicon nitride and silicon oxide, respectively, were prepared by reactive ultrahigh vacuum ion b…
A spherical, disordered, wormhole-like nanocomposite, consisting of 115 nm diameter MCM-41 particles containing 3 nm diameter Pt nanoparticles (see Figure), is described. A surfactant that stabilizes and prevents aggregation of the Pt nanoparticles during synthesis is removed by calcination, resulting in a high Pt cat…
The structural, thermodynamic and optical properties of ${\mathrm{Mg}}_{2}\mathrm{Ni}$ thin films covered with Pd are investigated upon exposure to hydrogen. Similar to bulk, thin films of metallic ${\mathrm{Mg}}_{2}\mathrm{Ni}$ take up 4 hydrogen per formula unit and semiconducting transparent ${\mathrm{Mg}}_{2}\math…
A novel method used to incorporate iron into the three-dimensional mesoporous cubic SBA-1 materials in highly acidic media is presented. The amount of iron present is controlled by simply adjusting the molar hydrochloric acid to silicon ratio. Moreover, the novel catalyst shows significantly higher phenol conversion a…
Robust, stimulus-responsive thin films are prepared by self-assembly of diblock-copolymer micelles from aqueous solution. Atomic force microscopy and fluorescence spectroscopy show that the hydrophobic polymer cores of block copolymer micelles adsorbed at high pH become localized cationic polymer brushes reversibly at…
We report the fabrication and characterization of a biologically sensitive field-effect transistor (Bio-FET) using a nanocrystalline diamond thin film. Biomolecular recognition capability was provided by linking human immunoglobulin G (IgG) to the diamond surface. Electrical measurements reveal behavior characteristic…
Ferromagnetism in Mn-doped GaAs, the prototypical dilute magnetic semiconductor (DMS), has so far been attributed to hole mediated RKKY-type interactions. First-principles calculations reveal a strong direction dependence of the ferromagnetic (FM) stabilization energy for Mn pairs, a dependence that cannot be explaine…
A magnetoelectric laminate composite consisting of magnetostrictive Terfenol-D (Tb1–xDyxFe2–y) and piezoelectric Pb(Zr,Ti)O3 layers has an extremely high voltage gain effect of ≈300 at its resonant state, offering potential for high-voltage miniature transformer applications.
A super-hydrophobic surface (see Figure), possessing a microscale and nanoscale hierarchical structure similar to the surface structure of the lotus leaf, was prepared in one step from a micellar solution of polypropylene-block-poly(methyl methacrylate).
The synthesis of single-crystalline diamond nanorods (with diameters of 4–8 nm and with lengths up to 200 nm) via the hydrogen plasma post-treatment of multiwalled carbon nanotubes is described. The diamond nanorods (see Figure) are identified as having a core–sheath structure with the inner core being diamond crystal…
We propose a theoretical model for branching instabilities in 2-dimensional fracture, offering predictions for when crack branching occurs, how multiple cracks develop, and what is the geometry of multiple branches. The model is based on equations of motion for crack tips which depend only on the time dependent stress…
A rational representation for the self--energy is explored to interpolate the solution of the Anderson impurity model in general orbitally degenerate case. Several constrains such as the Friedel's sum rule, positions of the Hubbard bands as well as the value of quasiparticle residue are used to establish the equations…