Materials Literature
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Carbon capsules with hollow core/mesoporous shell (HCMS) structures have been synthesized (see Figure for schematic) for the first time using solid core/mesoporous shell (SCMS) silica spheres as templates. The capsules have bimodal pore systems consisting of a uniform, tunable, hollow macroscopic core and a mesoporous…
A simple synthesis of high-quality Cu2O, a material of high interest in optics because of its photon exciton interconversion properties, in the form of nanowires (see Figure for a TEM image) is reported by the authors. Reduction of Cu(OH)2, freshly prepared from CuCl2, with hydrazine hydrate in basic solution in the p…
Nanowalls, a new nanostructural morphology of carbon, grow instead of nanotubes under microwave plasma-enhanced CVD conditions on substrates electrically disconnected from the lower electrode. While not fully understood, the formation of nanowalls (see Figure for top view) appears to depend on the local electric field…
Existing phenol production processes tend to be energy-consuming and produce unwanted by-products. We report an efficient process using a shell-and-tube reactor, in which a gaseous mixture of benzene and oxygen is fed into a porous alumina tube coated with a palladium thin layer and hydrogen is fed into the shell. Hyd…
Properties of materials determined by their size are indeed fascinating and form the basis of the emerging area of nanoscience. In this article, we examine the size dependent electronic structure and properties of nanocrystals of semiconductors and metals to illustrate this aspect. We then discuss the chemical reactiv…
Semiconductors and metals exhibit unusual optical, electronic, and magnetic properties on the nanometer scale. Chemists and materials scientists are developing methods to make non-spherical shapes of semiconductors and metals on the nanometer scale. We use a seed-mediated growth approach to make metallic nanorods and…
We investigate the properties of classical single flip dynamics in sets of two-dimensional random rhombus tilings. Single flips are local moves involving three tiles which sample the tiling sets via Monte Carlo Markov chains. We determine the ergodic times of these dynamical systems (at infinite temperature): they gro…
Raman spectra of iodine-doped single-walled carbon nanotube (I-SWNT) bundles excited with 514.5 nm were studied at room temperature and elevated pressure up to 7 GPa. The low frequency modes in I-SWNT exhibit very small pressure-induced frequency shifts, in contrast to the pressure shift of \ensuremath{\sim}7 ${\mathr…
Si3N4 particles coated with 20 nm TiN have been sintered by spark plasma sintering (SPS) at 1600 °C. The 25 vol.% TiN ceramic achieved a relative density of 91% without sintering additives. TEM and HREM observations indicate that a glassy phase derived from the Si3N4 particles plays a role in densification. Ceramics d…
Y 2 O 3 nanoparticles have been synthesized by subambient homogeneous reduction using alkalide solutions and subsequent oxidation. As synthesized, the material consists of free flowing, well-defined 1−3 nm particles. Annealing in air at temperatures between 100 and 400 °C results in transformation of the material to i…
Recently, a novel narrow-gap semiconductor ${\mathrm{CsBi}}_{4}{\mathrm{Te}}_{6}$ has been discovered with greater potential for low-temperature applications than the best existing high-performance thermoelectrics, ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ and its alloys. Electronic structure calculations in this bulk syst…
We have found that addition of 1-ethyl 3-(3-(dimethylamino)propyl)carbodiimide (EDC) to a suspension of sulfated polystyrene (PS) nanoparticles leads to formation of an irregular, dense-packed monolayer of self-assembled particles on homogeneous as well as chemically patterned surfaces. The adsorption process depends…
New polynucleating ligands based on a combination of a meso-tetrakis(phenyl)porphyrin core and four catecholamido units connected at the ortho positions of the phenyl moieties have been prepared. All four atropoisomers of the methoxy-protected meso-tetrakis(o-catecholamidophenyl)porphyrin 2 were obtained in high yield…
Cooperative emission has been recorded in several ${\mathrm{Yb}}^{3+}$ stoichiometric crystals. Its intensity, normalized by the square of the ${}^{2}{F}_{5/2}$ excited level population, is shown to depend only on the ${\mathrm{Yb}}^{3+}$ ions spatial distribution. In most cases, other material dependent parameters do…
The term biomimicry first appeared in 1962 as a generic term including both cybernetics and bionics. It referred to all sorts of imitation of one form of life by another one, while the term “bionics”, defined as “an attempt to understand sufficiently well the tricks that nature actually uses to solve her problems”, is…
The direct synthesis is reported of a 3R2 polytype of a hydrotalcite-like mineral by the hydrothermal treatment of aluminium oxide and magnesium oxide.
To test the influence of the surrounding medium on the relaxation dynamics of the plasmon band bleach recovery of gold nanoparticles after excitation with femtosecond laser pulses, we embedded 14.5 and 12.1 nm colloidal gold nanoparticles (synthesized electrochemically) in MgSO 4 powder and investigated these samples…
The binary antimonide Mo3Sb7 is metallic with poor thermoelectric properties. Since band structure calculations indicated a possible change to semiconducting behavior by adding two more valence-electrons, the substitutional series Mo3Sb7 − δTeδ has been investigated. Te atoms can replace up to 2.3 Sb atoms in Mo3Sb7 w…
In this work fundamental properties of the electrical transport of single-walled carbon nanotubes as a function of their length are investigated. For this purpose, we have developed a new technique that allows us to characterize electronic transport properties of single-walled carbon nanotubes by probing them at diffe…
We present an ab initio calculation of the electron energy loss spectrum of rutile TiO2 in the energy range of 0 to 60 eV, focusing our interest on the excitation from the titanium 3p semicore levels. The results are compared to our measurements. Local field effects turn out to be crucial at those energies, and their…