Materials Literature
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Reaction mechanisms between titanium isopropoxide and deuterated water in the atomic layer deposition (ALD) of TiO2 at 150–350 °C were studied using a quartz crystal microbalance (QCM) and a quadrupole mass spectrometer (QMS). The temperature had no marked effect on the total amount of the main gaseous by-product (CH3…
Fully dense doped-ZnO varistors with sub- micrometer grain size (see Figure for a TEM image) can be fabricated by a strategic two-stage, one-cycle, thermal processing method at temperatures as low as 825 °C. The nonlinear coefficients α of such fully dense varistors are as high as 270, which is more than one order of…
Due to the effects of surface electromigration, waves can propagate over the free surface of a current-carrying metallic or semiconducting film of thickness h_0. In this paper, waves of finite amplitude, and slow modulations of these waves, are studied. Periodic wave trains of finite amplitude are found, as well as th…
We study the light transmission in two-dimensional photonic crystal waveguides with embedded nonlinear defects. First, we derive the effective discrete equations with long-range interaction for describing the waveguide modes, and demonstrate that they provide a highly accurate generalization of the familiar tight-bind…
A new kind of memory effect on low frequency dielectric measurements on plexiglass (PMMA) is described. These measurements show that cooling and heating the sample at constant rate give an hysteretic dependence on temperature of the dielectric constant $ε$. A temporary stop of cooling produces a downward relaxation of…
We investigate the formation of spiral crack patterns during the desiccation of thin layers of precipitates in contact with a substrate. This symmetry-breaking fracturing mode is found to arise naturally not from torsion forces, but from a propagating stress front induced by the fold-up of the fragments. We model thei…
We propose a new method to characterize the geometrical texture of a granular packing at the particle scale including the steric hindrance effect. This method is based on the assumption of a maximum disorder (entropy) compatible both with strain-induced anisotropy of the contact network and steric exclusions. We show…
Current-carrying and superconducting systems can be treated within density-functional theory if suitable additional density variables (the current density and the superconducting order parameter, respectively) are included in the density-functional formalism. Here we show that the corresponding conjugate potentials (v…
We present an O(N) algorithm to study the vibrational properties of amorphous silicon within the framework of tight-binding approach. The dynamical matrix elements have been evaluated numerically in the harmonic approximation exploiting the short-range nature of the density matrix to calculate the vibrational density…
We have measured the longitudinal resistivity and the Hall resistivity in the ab-plane of highly c-axis-oriented MgB2 thin films. In the normal state, the Hall coefficient (R_H) behaves as R_H ~ T with increasing temperature (T) up to 130 K and then deviates from that linear T-dependence at higher temperatures. The T^…
Rapid development of information technologies originates from the exponential increase in the density of information that can be processed, stored, and transfer by the unit area of relevant devices. There is, however, a growing amount of evidences that the progress achieved in this way approaches its limits. Various n…
A novel in-situ polymerization approach has been used to manufacture polyolefin–clay nanocomposites (see Figure) with amazingly enhanced performance. The nanocomposites demonstrate reduced thermal expansion coefficients, improved melt flow strengths, increased heat-distortion temperatures, and lowered gas diffusion co…
Cellulose fibers have been successfully grafted with poly(methyl acrylate) using atom transfer radical polymerization, mediated by Me6-TREN and Cu(I)Br at ambient temperature. The initially hydrophilic cellulose was first modified by reacting the hydrozyl groups with 2-bromoisobutyryl bromide whereupon methyl acrylate…
The oxygen/silver system exhibits unique catalytic behavior for several large-scale oxidation (and partial oxidation) industrial processes. In spite of its importance, very little is known on the microscopic level concerning the atomic geometry and chemical nature of the various O species that form. Using density-func…
The spin-dependent electronic structure of thin epitaxial films of magnetite, ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(111),$ has been investigated at room temperature by means of spin-, energy-, and angle-resolved photoemission spectroscopy. Near the Fermi energy ${E}_{F}$ a spin polarization of $\ensuremath{-}(80\ifmmode\…
The stability of the shapes of crystal growth face and dissolution face in a two-dimensional mathematical model of crystal growth from solution under microgravity is studied. It is proved that the stable shapes of crystal growth face and dissolution face do exist, which are suitably shaped curves with their upper part…
Nanocrystalline silicon (nc-Si) films were deposited by plasma-enhanced chemical vapor deposition using SiF 4 /SiH 4 /H 2 . The structural and optical properties of the nc-Si films were examined by varying the deposition temperature, T d , for two different series of films with different H 2 and SiF 4 flow rates: [H 2…
Hydrogen-induced ferroelectric degradation of Pb(Zr,Ti)O 3 (PZT) films was studied by measuring the hysteresis curves after hydrogen annealing at various temperatures and times. It was found that hydrogen annealing at temperatures below 100°C resulted in an increase of remanent polarization due to the accumulation of…
The characteristics of oxides grown on silicon wafers under external mechanical stress were studied. It was found that the SiO 2 films grown under external compressive stress had a decreased etching rate. From capacitance–voltage ( C – V ) measurements, it was observed that a tensile sample had a reduced interface sta…
The influence of the electrical field on the variable range hopping process of porous carbon networks is examined in the range of validity of the law ln σ(T)∝T−1/2, where σ and T mean electrical conductivity and temperature, respectively. We show that the field dependence of the samples investigated in the vicinity of…