Materials Literature
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We have produced nanocrystalline titanium dioxide films with different structures (anatase or rutile) by depositing mass selected clusters from the gas phase. Nanoparticles are produced by a pulsed microplasma cluster source and are selected by aerodynamic separation effects. We have characterized nanocrystalline film…
Glasses are known to possess some puzzling features among condensed matter systems, as shown by the Kauzmann paradox. We show that if the coherent interaction mechanisms of Quantum Electrodynamics are taken into account, glasses are nothing but molecular liquids in which a large fraction of the molecules enter a colle…
The electronic structure and spin asymmetry of metal phthalocyanines (Pcs) (metal = Mn, Fe, Cu, and Mg) and metal-free Pc thin films of 1-monolayer (ML) thickness on an Fe(100) substrate were investigated using spin-polarized metastable deexcitation spectroscopy (SPMDS). The surface density-of-states (SDOS) of these P…
Cd 1− x Zn x S nanoparticles with different compositions (0⩽ x ⩽1) embedded in silica matrix were prepared in thin film form by the sol–gel technique. The film texture and structural transformation with increasing x value were studied from transmission electron micrographs and electron diffraction patterns. Optical st…
The synthesis of mellophanic dianhydride (MPDA), an isomer of pyromellitic dianhydride (PMDA), was studied. A trend of forming cyclic oligomers in the reactions of MPDA with 4,4‘-oxydianiline (ODA) or 4,4‘-methylenedianiline (MDA) in DMAC was found. The cyclic dimer from MPDA/MDA was isolated and fully characterized,…
Complex reactions taking place between Ca 3 SiO 5 and water can be considered the main cause for setting and hardening of Portland cement pastes. The “in situ” kinetics of the “hydration” process has been recently studied, as a function of time, using neutron scattering to obtain the trend of the fraction of free wate…
We report experimental data on the enthalpy relaxation of a hyperquenched silicate glass subjected to long-time aging (annealing) below the glass-transition temperature (Tg). The relaxation of a hyperquenched glass substantially differs from that of a normally cooled glass. Two mechanisms govern the relaxation of a hy…
Variable dose (VD), T m – T stop , initial rise (IR), variable heating rate (VHR), peak shape (PS) and computerized glow curve deconvolution (CGCD) methods are used to determine the number of peaks, the order of kinetics ( b ), the activation energy ( E a ) and attempt-to-escape frequency ( s ) associated with the glo…
Formation of intensity gratings was studied with two s-polarized (s+s) writing beams in polymer liquid crystals (PLCs) containing a photochromic moiety (azobenzene) and a mesogenic unit (tolane, T-AB; cyanobiphenyl, CB-AB ) by means of photoinduced change in alignment of PLCs. Remarkable differences were observed betw…
Abstract Two series of poly(ester urethane)s were prepared, containing polycaprolactone (PCL) as the soft segment with molecular weights of 530 and 2000. In each series, the soft‐segment/hard‐segment ratio was varied, and the morphological changes were monitored with differential scanning calorimetry, dynamic mechanic…
We consider a system where a spherical particle is suspended in a nematic liquid crystal confined between two walls. We calculate the liquid-crystal-mediated potential of mean force between the sphere and a substrate by means of Monte Carlo simulations. Three methods are used: a traditional Monte Carlo approach, umbre…
Biodirected epitaxial nanodeposition of polymers was achieved on a template with an oriented molecular surface. Acetobacter xylinum synthesized a ribbon of cellulose I microfibrils onto a fixed, nematic ordered substrate of glucan chains with unique surface characteristics. The substrate directed the orientation of th…
The infrared and Raman spectroscopic study of pyrrole-2-carboxylic acid (PCA) confirms the formation of the cyclic acid dimer species in the solid state. The molecular structure, vibrational frequencies, and binding energies of cyclic dimers have been also examined using the density functional theory (DFT) at the B3LY…
Ab initio molecular dynamics room-temperature simulations and full relaxation of atomic positions are performed in the study of adsorption sites on the octahedral and tetrahedral surfaces (parallel to the (001) plane) of the kaolinite group of clay minerals. Interactions of water and acetic acid molecules with both su…
Mechanical properties of homopolymers containing either solid spheres, rods, or platelets are compared using a three-dimensional lattice spring model, and thus, the effects of filler geometry on the mechanical behavior of the composite are isolated. In addition, the properties of exfoliated and intercalated nanocompos…
Properties are presented for random and enhanced 〈100〉 orientation SrTiO3 and BaxSr1−xTiO3 (x=0.33, 0.50, and 0.67) films fabricated on base-metal 〈100〉 Ni tapes using a chemical solution deposition approach. Films were crystallized in a reducing atmosphere, which prevented Ni oxidation, but permitted growth of SrTiO3…
By studying the Hall effect in a series of low resistivity Ga1−xMnxAs samples, accurate values for the hole density p, Mn concentration x, and Curie temperature TC are obtained over the range 0.015⩽x⩽0.08. The hole density corresponds to 90% of the Mn concentration at low x, and has a maximum value of 1.0×1027 m−3 whe…
The nonlinear rheological properties of dense suspensions are discussed within simplified models, suggested by a recent first principles approach to the model of Brownian particles in a constant-velocity-gradient solvent flow. Shear thinning of colloidal fluids and dynamical yielding of colloidal glasses arise from a…
The effect of dense grafting on the polymer brush's conformation is studied by small-angle neutron scattering on well-defined branched copolymers. We have determined the persistence length l p of the backbone of poly(chlorovinyl ether) grafted with polystyrene (PCEVE- g -PS) copolymers. In a good solvent, this length…
A general method is described for the electrodeposition of long (>500 μm) nanowires composed of noble or coinage metals including nickel, copper, silver, and gold. Nanowires of these metals, with diameters in the range from 60 to 750 nm, were obtained by electrochemical step edge decoration (ESED), the selective elect…