Materials Literature
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Motivated by the concept of geometrical frustration, we introduce a class of statistical mechanics lattice models for the glass transition. Monte Carlo simulations in three dimensions show that they display a dynamical glass transition which is very similar to that observed in other off-lattice systems and which does…
A charge neutral complex (CNC) was formed in aqueous solution by combining an orange light emitting anionic conjugated polyelectrolyte and a saturated cationic polyelectrolyte at a 1:1 ratio (per repeat unit). Photoluminescence (PL) from the CNC can be quenched by both the negatively charged dinitrophenol (DNP) deriva…
Ultrananocrystalline diamond (UNCD) films grown from hydrogen-poor plasmas have grain sizes of 3--10 nm, resulting in a large number of grain boundaries. We report on density-functional-based tight-binding molecular-dynamics calculations of high-energy high-angle twist (100) grain boundaries in diamond as a model for…
Using a combined experimental and theoretical approach, we address C $1s$ core-level shifts in amorphous carbon. Experimental results are obtained by x-ray photoelectron spectroscopy (XPS) and electron-energy-loss spectroscopy (EELS) on thin-film samples of different atomic density, obtained by a pulsed-laser depositi…
We review a class of new computer simulation methods for polymeric fluids and other soft condensed matter systems that are based on an underlying field-theoretic description. These methods, while still in an early stage of development, show considerable promise for studying the equilibrium properties of many-component…
The electronic structure and the location of muonium centers (Mu) in single-crystalline ZnO were determined for the first time. Two species of Mu centers with extremely small hyperfine parameters have been observed below 40 K. Both Mu centers have an axial-symmetric hyperfine structure along with a [0001] axis, indica…
Coherent electron transport in double-barrier heterostructures with parallel electric and magnetic fields is analyzed theoretically and with the aid of a quantum simulator accounting for 3-dimensional transport effects. The onset-voltage shift induced by the magnetic field in resonant tunneling diodes, which was previ…
We have studied the effect of pressure on the stretching and bending modes of (PO 4 ) 3- molecular groups in undoped Li 3 PO 4 and (MnO 4 ) 3- groups in Mn 5+ -doped Li 3 PO 4 using Raman spectroscopy and luminescence. The high-pressure Raman spectroscopy study confirmed an irreversible phase transition from the high-…
We characterize the microscopic processes that take place during polarization reversal in the tetragonal phase of a monodomain order–disorder perovskite ferroelectric using molecular-dynamics simulation. Microscopically the polarization of each unit cell reorients from an [001] orientation to an [001̄] orientation thr…
Spin-polarized tunneling was demonstrated on La0.7Sr0.3MnO3 epitaxial thin film with a La0.7Sr0.3MnO3-coated PtIr tip at room temperature. A magnetic-field-dependent gap structure was found in the differential tunneling spectra due to the spin-valve effect. The spatial mapping of the differential tunneling conductance…
The encapsulation of monomer molecules in liquid crystal droplets dispersed in a thermoplastic matrix provides a convenient method to control the orientation of liquid crystal directors. The imprint of droplet interfaces is obtained by photopolymerization of monomer molecules by means of a polymerization induced phase…
ZrO 2 :Mn , Cl luminescent powders have been synthesized at temperatures ranging from 250 to 500 °C. X-ray diffraction measurements indicate changes in the crystallinity of the material as a function of the processing temperature. The photoluminescence spectra show bands associated with transitions from the 4T1 level…
In order to provide experimental support for quantum confinement models describing electronic effects in porous silicon (p-Si), the Si 2s and Si 2p plasmon losses have been studied by x-ray photoelectron spectroscopy. The p-Si plasmon energy was found at a value 0.8÷1.6 eV higher than that of bulk Si (17.4 eV), as mea…
A Cu/ZrW 2 O 8 metal matrix composite was thermally cycled between 298 and 591 K while being subjected to x-ray diffraction in transmission using high-intensity synchrotron radiation. The reversible allotropic phase transformations of ZrW 2 O 8 between its two low-pressure phases and its high-pressure phase were obser…
This work investigates the effect of hydrostatic pressure on the excitation and emission spectra, as well as on the lifetime, of Al 2 O 3 :Ti 3+ at room temperature. The aim is to establish correlations between the pressure-induced band shifts and the corresponding local structural changes undergone by the TiO 6 compl…
We have performed variable-temperature multimode quantitative microwave microscopy of in situ epitaxial Ba1−xSrxTiO3 thin-film composition spreads fabricated on (100) LaA1O3 substrates. Dielectric properties were mapped as a function of continuously varying composition from BaTiO3 to SrTiO3. We have demonstrated nonde…
The fabrication, initial structural characterization, and diode measurements are reported for a boron carbide/silicon carbide heterojunction diode. Current–voltage curves are obtained for operation at temperatures from 24 to 351 °C. Plasma-enhanced chemical-vapor deposition (PECVD) -deposited undoped boron carbide mat…
Recently the study of liquid drainage through foams has generated considerable experimental and theoretical research. This research has usually made the assumptions that the liquid content is very low and that the viscous resistance is limited to occurring within either the Plateau borders or vertices. This paper pres…
The magnetic, structural, and transport properties of the Heusler alloy Co2MnSi are reported for sputtered thin films and a single crystal. X-ray diffraction reveals a phase pure L21 structure for all films grown between 573 and 773 K. Films grown at 773 K display a four-fold decrease in the resistivity relative to th…
We report the observation of giant photoresistivity in electrochemically self-assembled CdS and ZnSe nanowires electrodeposited in a porous alumina film. The resistance of these nanowires increases by one to two orders of magnitude when exposed to infrared radiation, possibly because of real-space transfer of electron…