Materials Literature
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We report here on the high-density preparation of single-wall tubes in the presence of mixed catalysts of the types Fe/Ni and Co/Ni, in the soot as well as in the weblike deposits forming in the chamber. The yield is much higher than previously reported, and gram quantities can be obtained. Diameters cover the range f…
X-ray absorption measurements from H-passivated porous Si and from oxidized Si nanocrystals, combined with electron microscopy, ir absorption, \ensuremath{\alpha} recoil, and luminescence emission data, provide a consistent structural picture of the species responsible for the visible luminescence observed in these sa…
Abstract Increasing demands to decrease engine weight and improve engine performance has led to an investigation to develop polymer composites capable of being used at 371°C and above in 4 atmospheres of air. The results of an investigation to determine the thermo‐oxidative stability (TOS) of various fluorinated polyi…
We report a novel approach for obtaining precise control of both p- and n-type dopant concentrations in bulk Ge single crystals. High-purity Ge single crystals of controlled 74Ge/70Ge isotope composition ratios were grown and subsequently doped by the neutron transmutation doping (NTD) technique. The resulting net-imp…
Neutral molecules are encapsulated in the cluster anions in the title, which were produced by solvothermal reactions of [nBu4N]3[H3V10O28] and PhAsO3H2 in CH3OH/H2O (99:1) with and without Et4NCl. The structures are shown schematically below.
We demonstrate here that the pattern evolution in a binary liquid mixture containing glass spheres is strongly affected by the dynamic coupling between phase separation and wetting. Because of the difference in the wettability to glass between the two phases, the glass particles are preferentially included in the more…
Vertex‐sharing BO 4 and PO 4 tetrahedra form the framework of the title compounds. Ca[BPO 5 ] and Sr[BPO 5 ] crystallize in the stillwellite structural type and contain tetrahedral chain anions [BPO ], which can be described as loop‐branched “dreier” single chains. In Ba 3 [BP 3 O 12 ] the tetrahedral anions form “zwe…
The unusual oxidation state + IV for iron centers can be stabilized by porphyrin-like corrole ligands in such a way that the compounds 1 (R Cl, Ph, OFe-corrole) can be isolated at room temperature. The oxygen-bridged binuclear iron(IV) corrole, which can be readily converted into the mononuclear iron(IV) corrole, fo…
Steady state and time resolved photoluminescence studies of type IIb boron-doped synthetic diamond reveal a new broad red emission band that exhibits many of the features of classic donor–acceptor pair recombination. This recombination is thought to be between an as-yet unidentified neutral donor, possibly nitrogen re…
We demonstrate a novel method for bond and etch back silicon on insulator in which an epitaxial Si layer over porous Si is transferred onto a dissimilar substrate by bonding and etch back of porous Si. The highest etching selectivity (100 000:1) between the porous Si and the epitaxial layer is achieved by the alkali f…
We combine a new synthesis with transient optical hole burning to observe and assign the size evolution (19 to 115 \AA{} diameter, \ensuremath{\sigma}5%) of a series of excited states in CdSe quantum dots. We observe an avoided crossing around the spin orbit energy in the hole spectra for \ensuremath{\sim}65 \AA{} dot…
Exchange of a β-methine unit for an N atom of a pyrrole ring of a porphyrin leads to a new type of porphyrin isomer, which is formed by condensation of pyrrole and P-tolylaldehyde. NiII ions are surprisingly coordinated by 1 as tetradentate ligand, that is through the three N atoms and the C atom of the inner cycle. T…
Using self-consistent field theory, we examine microphases of diblock copolymers and find, in addition to lamellar, hexagonal, and cubic phases, a stable gyroid phase which occurs between the lamellar and hexagonal ones. It terminates at a triple point, with a lamellar to hexagonal transition occurring in the weak-seg…
The birefringent and piezooptic properties of (MgSiF6) · 6H2O crystals are investigated. The second-order phase transition at Ti = 353 K is observed for the first time. It is shown that the investigated crystals possess properties characteristic of an incommensurate phase in the temperature range 298 to 353 K. The tra…
Abstract Polyisoprene (PIP) was found to react with trifluoroacetic acid (TFA) to give an adduct. Saponification of the ester gave a new alternating copolymer of ethylene and α‐methyl vinyl alcohol. TFA did not react with polybutadiene (PBD) under these conditions, thus providing a way to produce amphiphilic block cop…
The formation energies and electronic structures of three kinds of Si impurities in diamond are studied using the modified neglect of differential overlap method and the discrete-variational local-density-functional method with cluster models. The results show that it is difficult for all of the silicon impurities (in…
Single-phase (Sr1−x,K2x)Zr4(PO4)6 ceramic (with x=0.0–0.8) demonstrated values of thermal conductivity decrease with increasing potassium content to a minimum value at x=0.5, which suggests a maximum content of lattice defect, i.e., oxygen vacancy, at this composition. The thermal conductivity of the ceramic then incr…
Auger photoelectron coincidence spectroscopy (APECS) confirms that a substantial part of the low-energy tail of the ${\mathit{L}}_{23}$VV Auger lines of the 3d transition metals is due to intrinsic initial- and final-state shake-up/shake-off processes and not just secondary losses. Data were collected for the ${\mathi…
The lamellar semiconductors GaSe and InSe have been studied with k-resolved inverse-photoemission spectroscopy along two major symmetry directions (\ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} K\ifmmode\bar\else\textasciimacron\fi{} and \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} M\ifmmode\b…
In order to optimize the magnetic properties of die-upset Pr-Fe-B magnets, we have systematically altered alloy compositions, including partial substitution of cobalt and neodymium, and low-level additions of gallium. In general, the remanences of Pr-Fe-B die-upset magnets were lower by ∼1 kG, and coercivities were hi…