Materials Literature
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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…
Cultures of the freshwater diatom Navicula pelliculosa were synchronized by silicon starvation, fed a 29Si-enriched silicate solution, and then studied by 29Si NMR spectroscopy. Two NMR resonances could be detected reproducibly, the ever-present orthosilicic acid peak at −71 ppm and a weak signal at −131.5 ppm that wa…
The effects of hydrogen impurities in the bulk and on the surface of aluminum are theoretically investigated. Within the framework of density-functional theory, we have obtained the dependence on H concentration of the stacking fault energy, the cleavage energy, the Al/H surface energy, and the Al/H/Al interface forma…
The morphological development of step edge patterns in the presence of meandering instability during step flow growth is studied by simulations and numerical integration of a continuum model. It is demonstrated that the kink Ehrlich-Schwoebel barrier responsible for the instability leads to an invariant shape of the s…
We investigate spin-polarized inter-band tunneling through measurement of a (Ga,Mn)As based Zener tunnel diode. By placing the diode under reverse bias, electron spin polarization is transferred from the valence band of p-type (Ga,Mn)As to the conduction band of an adjacent n-GaAs layer. The resulting current is monit…