Materials Literature
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Oxide superlattices composed of antiferromagnetic insulator layers of CaMnO3 (10 unit cells) and paramagnetic metal layers of CaRuO3 (N unit cells) were fabricated on LaAlO3 substrates by pulsed-laser deposition. All the superlattices show ferromagnetic transitions at an almost identical temperature (TC∼95 K) and nega…
We review a series of works where the fundamental master equation is used to develop a microscopical description of evolution of non-equilibrium atomic distributions in alloys. We describe exact equations for temporal evolution of local concentrations and their correlators as well as approximate methods to treat these…
Analytical expressions for the binding energy of electrons and positrons in dielectric clusters, analysed in this work, neglect the elastic effects. Therefore, we present the density-functional theory for neutral liquid clusters that experience the spontaneous deformation. Using the 1/R -expansion, $R$ being the clust…
Abstract Both isotropic and uniaxially anisotropic media capable of supporting backward waves are reviewed. Such an effect recently has been of great interest, and certain man‐made composite media have been introduced under the names “media with negative refraction factor” or “left‐handed materials,” effective in a ce…
The magnetic behavior of 100 nm period arrays of Ni nanowires embedded in a highly ordered alumina pore matrix were characterized by magnetometry and magnetic force microscopy. Reducing the diameter of the nanowires from 55 to 30 nm while keeping the interwire distance constant leads to increasing coercive fields from…
A phase-field formulation is introduced to simulate quantitatively microstructural pattern formation in alloys. The thin-interface limit of this formulation yields a much less stringent restriction on the choice of interface thickness than previous formulations and permits one to eliminate nonequilibrium effects at th…
Single wall carbon nanotubes (SWCNTs) have been used as the active channels of field effect transistors (FET). The next development step involves the integration of CNTFETs to form logic gates; the basic units of computers. For this we need to have both p- and n-type CNTFETs. However, without special treatment, the ob…
Fragility is viewed as a measure of the loss of rigidity of a glass structure above its glass transition temperature. It is attributed to the weakness of directional bonding and to the presence of a high density of low-energy configurational states. An a priori fragility function of electronegativities and bond distan…
The relationship between metal particle structure and the reactivity and selectivity of oxide−supported metal catalysts has been explored here with well-defined Pt particles on the Zn-terminated ZnO(0001)−Zn surface, using X-ray photoelectron spectroscopy (XPS), ion scattering spectroscopy (ISS), and temperature-progr…
The average near-surface orientation of the main and side chains of polyimide (PI) for liquid crystal (LC) alignment has been studied by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. A detailed analysis of the angular dependences of resonance intensities revealed that rubbing causes the inclination…
The photochromic and solvatochromic behavior of four phenanthroline-containing spirooxazines bearing various alkyl long-chain substituents has been investigated in different polar and nonpolar solvents at various temperatures. These derivatives always appeared in an equilibrium mixture of spiro forms and open merocyan…
The structure of a MnO x /Al 2 O 3 catalyst used for ozone decomposition was evaluated using extended X-ray absorption fine structure (EXAFS) and in situ Raman spectroscopy. EXAFS results suggest that the manganese center is surrounded by four or five oxygen atoms with a Mn−O distance of 0.21 nm. The Raman frequency f…
Combined in situ X-ray absorption fine structure (XAFS) measurements and density functional theory (DFT) computations yield a quantitative three-dimensional picture of the six-coordinated Ti IV -centered active site (in Ti/SiO 2 catalysts) during production of epoxides from alkenes in the presence of hydroperoxide as…
A genuine and original trinuclear gadolinium complex in which the three Gd centers are linked by three different phenolato or hydroxo bridges presents an antiferromagnetic interaction of 0.19 cm-1. This J value is among the largest ones found for interacting Gd centers.
In this work we have addressed the gold particle catalyzed eosin reduction in the presence of NaBH 4 . The catalytic activity of the gold nanoparticles is different for different size regimes (size domain dependent) of the particles. It has been shown that the kinetics of the catalytic rate has a bearing with the part…
I am puzzled by the report that the chirality of aggregates of certain porphyrin derivatives can be influenced by the direction of turning the solution in a rotary evaporator, put forward by J. M. Ribo and co-authors (Reports, “Chiral sign induction by vortices during the formation of mesophases
Single crystals of Ba8CoRh6O21, grown out of a potassium carbonate flux, were characterized by single-crystal X-ray diffraction and magnetic measurements. X-ray data were collected in a superspace group approach and solved using the JANA2000 software package. Ba8CoRh6O21 represents the first example of a structurally…
The densification behavior of nanocrystalline Ce 0.8 RE 0.2 O 1.9 (RE = La, Nd, Sm, Gd, Dy, Y, Ho, Er, and Yb) solid-solution oxides, synthesized via carbonate coprecipitation, has been investigated in air by means of constant-rate-of-heating sintering and the conventional ramp-and-holding sintering methods. Fully den…
Lead zinc niobate-lead titanate (PZN-PT) single crystals are able to sustain very large piezoelectric strains, a phenomenon for which the term `giant piezoelectric effect' was recently coined. PZN-4.5%PT crystals were studied by means of single-crystal neutron diffraction at temperatures between 293 K and 438 K. Two p…
The photoluminescence spectra of spherical CdTe nanocrystals with zincblende structure are studied by size-selective spectroscopic techniques. We observe a resonant Stokes shift of 15 meV when the excitation laser energy is tuned to the red side of the absorption band at 2.236 eV. The experimental data are analyzed wi…