Materials Literature
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The electronic structure of the charge density wave (CDW) bronze (PO2)(4)(WO3)(2m), m = 4, is determined using ab initio density functional theory. The calculation shows that the Fermi surface (FS) consists in the superposition of three one-dimensional FS's associated with three types of chains. The q dependence of th…
We propose a simple semiphenomenological model to describe the dynamics of polymer melt intercalation in the gallery between the adjacent clay sheets in polymer-clay nanocomposites. Within this model, the intercalation process is driven by the motion of localized excitations ("kinks") which open up the tip between the…
Boron carbon nitride (BCN) films have been grown by B4C evaporation with concurrent N2+ ion assistance, and have been characterized by x-ray absorption near edge (XANES) spectroscopy. Upon the nitrogen insertion, the film structure evolves from BxC-like to h-BN-like. The hexagonal structure corresponds to a true terna…
The resistivity of La0.82Ca0.18MnO3 single crystal has been investigated as a function of external magnetic field and separately under an applied current flow. The measurements were carried out at various temperatures below and above the ferromagnetic transition temperature TC. It has been found that the dynamic elect…
We present a framework coupling continuum elasto-viscoplasticity with three-dimensional discrete dislocation dynamics. In this approach, the elastic response is governed by the classical Hooke’s law and the viscoplastic behavior is determined by the motion of curved dislocations in a three-dimensional space. The resul…
Titania (TiO2) is employed as a host for the Eu3+ activator ion. Thin films were produced by the sol-gel method on silicon and corning glass substrates and, depending on the nature of the substrate, they present different crystalline structure. The films show an intense red photoluminescence associated with the D05→7F…
To determine the effects of grain structures on the rate of electromigration-induced failure of Cu interconnects, scanned laser annealing (SLA) has been used to produce Cu interconnects with very different grain structures. SLA, in which a moving hot-zone induces local grain growth, can be used to produce interconnect…
Electrochemical doping of single-wall carbon nanotube (SWNT) films and concomitant changes in their electronic states were investigated by in situ measurements of optical absorption spectra as well as of ac resistance using a nonaqueous electrolyte solution. A systematic, consistent, and reversible variation of these…
High doses (1015–5×1016 cm−2) of Mn+ ions were implanted into p-GaN at ∼350 °C and annealed at 700–1000 °C. At the high end of this dose range, platelet structures of GaxMn1−xN were formed. The presence of these regions correlated with ferromagnetic behavior in the samples up to ∼250 K. At low doses, the implanted led…
The recently discovered superconductor MgB2, with a transition temperature of 39K, has significant potential for future electronics. An essential step is the achievement of Josephson circuits, of which the superconducting quantum interference device (SQUID) is the most important. Here, we report Josephson quantum inte…
A constitutive model is derived for the time-dependent response of particle-reinforced elastomers at finite strains. An amorphous rubbery polymer is treated as a network of long chains linked by permanent junctions (chemical crosslinks, entanglements and filler particles). A strand between two neighboring junctions is…
This study investigates structural similarities in polyfluorosilicone (PFSi) gels made by different cross-linking procedures, using small-angle neutron scattering (SANS). The scattering properties of gels prepared from long and short precursor chains and of the un-cross-linked polymer solutions are reported. The gel s…
Phenol mineralization in the aqueous phase was studied employing oxygen as the oxidant. The reaction was carried out at intermediate oxygen pressures (3.2−16 bar) and temperatures (127−180 °C) employing a commercial catalyst supplied by Engelhard (Cu-203T). Two experimental setups were used: a basket stirred-tank reac…
We examined the epitaxial growth of ZnO films on a sapphire (0001) substrate by an atmospheric pressure atomic layer epitaxy technique using ZnCl 2 and O 2 sources. The films were deposited epitaxially in a substrate temperature range of 450−550 °C with a constant growth rate of 0.26 nm/cycle. It is noteworthy that th…
The surface segregation of a fluorochemical additive from a polyolefin host matrix has been investigated by X-ray photoelectron spectroscopy, optical microscopy, tapping mode atomic force microscopy, imaging time-of-flight secondary ion mass spectrometry, and contact angle analysis. The level of surface enrichment has…
The molecular mechanics and dynamics calculations, kinetics, and laser-excited luminescence studies were carried out for trivalent lanthanide (Ln(3+)) complexes of macrocyclic polyaminopolycarboxylate ligands TETA and DOTA (where TETA is 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid and DOTA is 1,4,7,10-…
The synthesis and structural characterization of the first examples of microporous europium(III) and terbium(III) silicates (Na(4)K(2)X(2)Si(16)O(38) x 10H(2)O, X = Eu, Tb) are reported. The structure of these solids was solved by powder X-ray diffraction ab initio (direct) methods and further characterized by chemica…
Certain emerging fields of nanotechnology depend on self-assembly processes that lead to molecular structures which are organized and ordered or disorganized and disordered. Many such processes can be understood as combinations of nucleation, reversible growth, and reversible aggregation. We develop a descriptive theo…
Dual-mode electron paramagnetic resonance (EPR), in which an oscillating magnetic field is alternately applied parallel or perpendicular to the static magnetic field, is a valuable technique for studying both half-integer and integer electron spin systems and is particularly useful for studying transition metals invol…
The ferroelectricity of BaTiO 3 is investigated with the plane-wave pseudopotential method and the LCAO quantum chemical approach in the framework of density functional theory (DFT). Potential energy surfaces of various atomic displacements and the influence of lattice strain and lattice volume on the surfaces are exa…