Materials Literature
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Crystals as building blocks: Self-assembled crystals are obtained through hierarchical and self-similar growth. Using microscopic, polyhedral, self-assembled crystals as building blocks, large crystals and open mesophase structures which preserve the shape and orientation of the basic structural units are spontaneousl…
Abstract A series of new polyimides containing s ‐triazine rings have been synthesized via Diels–Alder intermolecular polymerization of 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine with various bis(maleimide)s. All the poly(imino‐ s ‐triazine imide)s were characterized by elemental analyses, FTIR spectral…
Iod als Leim für Nanoaggregate: Mit der spontanen Chemisorption von Iod auf Gold-Nanopartikeln geht eine Elektroneninjektion von Iod auf Gold einher, was zur Fusion der Nanopartikel und schließlich zur Aggregation führt; ein Überschuss an KI führt zur Bildung von Nanokristallen (siehe Schema). Oberflächengebundene und…
Abstract The phonon dispersion curves for α‐SiO 2 crystals were calculated on the basis of a rigid‐ion model. The first‐order Raman spectra of the A 1 mode of the α‐SiO 2 crystal were measured in the temperature range from 303.1 to 773.1 K. The temperature dependence of the linewidth was analyzed by using the phonon d…
Abstract Films of polymer blends having various contents of poly(vinyl alcohol) (PVA) and polyacrylamide (PAM) were prepared by the solution casting technique using water as a common solvent. The thermal, mechanical and morphological properties of these blends before and after exposure to various doses of gamma radiat…
Abstract Butylammonium hexafluorosilicate, (n‐C 4 H 9 NH 3 ) 2 SiF 6 , crystallizes at room temperature in the trigonal system with a probable space group P 321. A new structural phase transition was detected at low temperatures for this compound by means of differential scanning calorimetry (DSC) and the basic thermo…
Received 14 January 2003DOI:https://doi.org/10.1103/PhysRevB.67.039902©2003 American Physical Society
N-type ZnO thin films were successfully grown by sol-gel dipping coat method on glass substrates at 300–600 °C under air atmosphere. Poly ZnO thin films were obtained at more than 300 °C. Values of full width at half maximum of (0002) peak at the XRD spectra became small with the increasing the substrate temperatures.…
Abstract Information about confinement effects and dot–matrix interactions of CdS nanoparticles was obtained from resonance Raman spectroscopy. The quantum dots had diameters of 3 and 5 nm and were prepared with and without organic spacer groups. It was found that the spacer improves the quality of the nanocrystallite…
We report resonant inelastic x-ray scattering experiments of the orbitally ordered manganite ${\mathrm{LaMnO}}_{3}.$ When incident photon energy is tuned near the Mn K absorption edge, the spectra reveal three features at 2.5, 8, and 11 eV. The 8- and 11-eV peaks are ascribed to transitions from the O $2p$ bands to th…
Calcination of a layered double hydroxide precursor containing MgII, FeII and FeIII cations with an Mg2+:(FeII + FeIII) ratio of 0.5 affords a pure ferrite spinel, MgFe2O4, which has a higher saturation magnetization than samples of the same material produced by conventional ceramic routes.
Monolayer protected gold nanoparticles synthesised by a two-phase method contain a significant amount of tetraoctylammonium bromide (TOABr), the quaternary ammonium salt used as the phase transfer reagent, as a persistently retained impurity. A simple purification protocol is described.
An original nanocone with 240° disclination arises naturally from a planar hexagonal sheet when four 60° segments originating from adjacent hexagonal centers are cut out of the plane and the severed edges of the segments are rejoined. The comparison among the calculated total energies of several pure carbon nanocones…
An unexpected dependence on concentration was found for the quadratic hyperpolarizability β of Zn complexes with stilbazole and CF3SO3− ligands (see values given), which reaches very large values on dilution. This is surprising, because the concentration used for determining β is traditionally not given in the literat…
Abstract In surface‐enhanced Raman scattering (SERS), the magnitude of enhancement is highly dependent on the nanometer‐scale morphological and optical properties of the substrate employed. This paper reports the development of an improved SERS‐active substrate that is based on a combination of nanoparticle assembly a…
The Holocene diatom flora identified in three sediment cores from marine bays in the Windmill Islands (East Antarctica) is described and depicted for the first time. One hundred and twenty-four diatom taxa could be identified of which eighty-one taxa have a circum-Antarctic distribution. All taxa are listed in a table…
Abstract Melt polycondensation of L ‐lactic acid (LA) was examined in the presence of binary catalyst systems consisting of SnCl 2 ·2H 2 O and metal alkoxides as co‐catalysts. Among the co‐catalysts examined, viz (Al(O i Pr) 3 ,Ti(O i Pr) 4 ,Y(O i Pr) 3 ,Si(OEt) 4 and Ge(OEt) 4 ), Ge(OEt) 4 was found to be the most ef…
Abstract Blended films of poly( L ‐lactide) [ie poly( L ‐lactic acid)] (PLLA) and poly(ϵ‐caprolactone) (PCL) without or mixed with 10 wt% poly( L ‐lactide‐ co ‐ϵ‐caprolactone) (PLLA‐CL) were prepared by solution‐casting. The effects of PLLA‐CL on the morphology, phase structure, crystallization, and mechanical propert…
This paper discusses the heterogeneous nucleation of solidification, treating the fundamental process as taking place by adsorption on the surface of the heterogeneous nucleant. A theoretical framework for adsorption and nucleation catalysis is described, and some related experimental results are discussed.
The structural properties and phase stability of the four common polytypes of boron nitride, cubic zinc blende (c-BN), hexagonal (h-BN), wurtzite (w-BN) and rhombohedral (r-BN), are studied by ab initio calculations. Electronic energies are calculated using an ultra soft pseudopotential method under the density-functi…