Materials Literature
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The electron and hole relaxation in the (7, 0) zigzag carbon nanotube is simulated in time domain using a surface-hopping Kohn-Sham density functional theory. Following a photoexcitation between the second van Hove singularities, the electrons and holes decay to the Fermi level on characteristic subpicosecond time sca…
The effects of flexibility and chemical composition in the variation of the glass transition temperature are obtained by using the Lindemann criteria, which relates melting temperature with atomic vibrations, and rigidity theory. Using this criteria and that floppy modes produce an excess of vibrational states at low…
Using Monte Carlo simulations within the empirical potential approach, we examine the effect produced by the surface environment on the atomic level stresses in tetrahedral amorphous carbon. Both the distribution of stresses and the distributions of sp^2 and sp^3 atoms as a function of depth from the surface are highl…
We report an experimental approach to making multifilament coated conductors with low losses in applied time-varying magnetic field. Previously, the multifilament conductors obtained for that purpose by laser ablation suffered from high coupling losses. Here we report how this problem can be solved. When the substrate…
YBaCo4O7 belongs to a new class of geometrically frustrated magnets like the pyrochlores, in which Co-spins occupy corners of tetrahedra. The structure can be viewed as an alternating stacking of Kagome and triangular layers. Exactly half of the triangular units of the Kagome plane are capped by Co ions to form column…
As devices are reduced in size, interfaces start to dominate electrical transport making it essential to be able to describe reliably how they transmit and reflect electrons. For a number of nearly perfectly lattice-matched materials, we calculate from first-principles the dependence of the interface transparency on t…
Abstract The effects of expandable graphite (EG) of different particle sizes, on the fire‐retardant properties of high‐density rigid polyurethane foam (RPUF) (0.45 g cm −3 ) were studied. Samples of EG with different particle sizes were obtained by pulverization in an ultra‐high‐speed mixer for 4 and 13 min, respectiv…
The aim of this Chapter is to provide an account of recent advances in the first-principles modeling of ferroelectric oxide nanostructures. Starting from a microscopic description of ferroelectricity in bulk materials and considering then, successively, different kinds of nanostructures (films, multilayers, wires, and…
This report describes the preparation and characterization of new magnetic fluorescent nanoparticles and our success in using them to label living cells. The bifunctional nanoparticles possess a magnetic oxide core composed of a dimercaptosuccinic acid (DMSA) ligand at the surface and a covalently attached fluorescent…
Tungsten oxide (WO3) thin films have been produced by KrF excimer laser (lambda = 248 nm) ablation of bulk ceramic WO3 targets. The crystal structure, surface morphology, chemical composition, and structural stability of the WO3 thin films have been studied in detail. Characterization of freshly grown WO3 thin films h…
Abstract The beautiful colours of many inorganic compounds, including minerals and gemstones, as well as the mysterious cold light of luminescence emitted by these materials, have attracted the inquisitiveness of natural philosophers for centuries. The scientific study of such phenomena - the optical spectroscopy of s…
Effect of side-chain substitutions on the morphology of self-assembly of perylene diimide molecules has been studied with two derivatives modified with distinctly different side-chains, N,N'-di(dodecyl)-perylene-3,4,9,10-tetracarboxylic diimide (DD-PTCDI) and N,N'-di(nonyldecyl)-perylene-3,4,9,10-tetracarboxylic diimi…
Macroporous ceramics with pore sizes from 400 nm to 4 mm and porosity within the range 20%–97% have been produced for a number of well‐established and emerging applications, such as molten metal filtration, catalysis, refractory insulation, and hot gas filtration. These applications take advantage of the unique proper…
Abstract The one-pot syntheses of partially oxidized cobalt(III) phthalocyanine salts with axial halides, as well as a shorter route (single-step) for the axial dicyano counterpart are reported. The method utilizes an electrolytic reaction, and appears to be solvent dependent. Overlap integral calculations and electri…
A many-body variable potential is used to study the structural phase transition of quartz. The most significant feature of this variable potential is that the parameters are separately fitted to two phases of quartz and are allowed to change as a function of temperature to account for any nuclear and electronic excita…
Norbornadiene (a C2v symmetry bicyclic rigid hydrocarbon) dissolved in three different nematic mesophases has been studied by liquid crystal NMR, to contribute to a better understanding of the influence of solvents on the solute's ordering and structure. The main results achieved by this work can be summarized as foll…
A script developed for crystal-chemical Rietveld refinement of P 6 3 / m apatite with TOPAS is implemented in parallel with standard structure refinement. Least-squares standard uncertainty (s.u.) values for directly extracted crystal-chemical parameters are nearly an order of magnitude lower than those obtained indir…
Abstract Vanadium pentoxide gels, V 2 O 5 ·1.6H 2 O, give rise to xerogel layers that exhibit a preferred orientation. X‐ray diffraction of this xerogel displays the 00 l peaks typical of a turbostratic stacking of the V 2 O 5 ribbons along a direction parallel to the substrate. The distance along the c ‐axis is obser…
International audience
A new method for calculating the total instrumental function of a conventional Bragg–Brentano diffractometer has been developed. The method is based on an exact analytical solution, derived from diffraction optics, for the contribution of each incident ray to the intensity registered by a detector of limited size. Bec…