Materials Literature
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We have measured depth-resolved microphotoluminescence (PL) and micro-Raman spectra on the cross section of porous silicon multilayers to sample different layer depths. The PL emission band gets stronger, blueshifts, and narrows at the high porosity layers. On the contrary, the Raman band weakens and broadens. This ba…
Boron nitride (BN) nanotubes were prepared by a high-temperature plasma jet method. While the BN nanotubes were found in quantity on the surface of a BN sintered disk, amorphous BN webs were found dominant in the water-cooled collector. These structures were studied on the basis of transmission electron microscopy obs…
This letter describes the formation of a thin amorphous layer at the tetragonal-Ta/Cu interfaces, which appear in copper metallization structures of microelectronic devices. The disordered layer grows up to 4 nm when annealed at between 400 and 600 °C. Since Ta and Cu are immiscible according to thermodynamic data, th…
The hitherto controversial valence states of nickel and tin in the ternary chalcogenide Ni(3)Sn(2)S(2) (see structure) have been determined by photoelectron and Mössbauer spectroscopy ((61)Ni, (119)Sn). Results from band structure calculations confirmed that this shandite phase is a metal and that the approximate dist…
Although known for almost 35 years, N-substituted corroles have only now been recognized as being chiral. Several examples of these species were prepared in a facile two-step synthesis and separated into their enantiomers by HPLC. The zinc(II) complex of the corrole shown schematically was also synthesized.
A possible mechanism for the photoemission from Si nanocrystals in an amorphous SiO 2 matrix fabricated by ion implantation is reported. We have measured the implantation dose and the temperature dependence as well as the oxidation effect of the photoluminescence behaviour of Si nanocrystals in SiO 2 layers fabricated…
Langmuir monolayers are formed from an amphiphilically decorated poly(para-phenylene), which indicates that its hydrophilic and hydrophobic parts segregate lengthwise along the polymer backbone in this nanometer-sized cylinder as illustrated in A. This polymer differs from known amphiphiles in that it consists of a li…
We report anti-Stokes photoluminescence (photon energy up-conversion) from size-quantized CdSe and InP nanocrystalline colloids. The observed up-conversion is highly efficient and occurs at very low excitation intensities. With low temperatures the intensity of the up-converted photoluminescence decreases while that o…
First-principles supercell calculations and the modern theory of polarization are used to compute the ${e}_{33}$ piezoelectric coefficients of $\mathrm{Pb}({\mathrm{Zr}}_{0.5}{\mathrm{Ti}}_{0.5}{\mathrm{O}}_{3})$ (PZT) and $0.60\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}){\mathrm{O}}_{3}+0.40{\mathrm{PbTiO}}_{3…
We report significant enhancements of magnetoresistance in granular (La0.67Ca0.33MnO3)x/(SrTiO3)1−x. The system exhibits a conduction threshold at x=xc∼60%, around which magnetoresistance versus x has a maximum. The composition xc at which maximum enhancement in magnetoresistance is observed is the same at high (aroun…
Within the framework of mean field theory, we study the effects of multi-surface modification on the Curie temperature of ferroelectric films using the transverse Ising model. The general nonlinear equations for Curie temperature of multi-surface ferroelectric films with arbitrary exchange constants and transverse fie…
The microscopic description of spin-Peierls substances is discussed. Particular attention is paid to the ordered (dimerised and incommensurably modulated) phases. Important points are the adiabatic and the antiadiabatic approach, generic soliton forms, elastic and magnetic interchain couplings. The wealth and the accu…
ZnO/Mg 0.2 Zn 0.8 O superlattices with a band-gap offset of about 0.5 eV were epitaxially grown by laser molecular-beam epitaxy on a sapphire(0001) substrate using a ZnO buffer layer. The superlattice structure with a period ranging from 8 to 18 nm was clearly verified by cross-sectional transmission electron microsco…
The effect of stearic acid concentration on the reversion behavior of epoxidized natural rubber (ENR 25 and ENR 50) was carried out in the temperature range of 150–180°C and 0.5–14.5 phr of stearic acid loading. Three common accelerators; namely, zinc dimethyldithiocarbamate (ZDMC), tetramethylthiuram disulfide (TMTD)…
The cation of the title compound, CI3HI4N~--C4H506-.H20, has a central guanidinium fragment with a planar geometry, as expected for sp 2 hybridization at the C atom. The conformation of the phenyl rings is syn-syn with respect to the unsubstituted N atom, but the overall conformation of the cation is far from the C2v…
Barium hexaferrite (BaM) thin films were deposited on (0001) LiTaO3 substrates by pulsed laser deposition. Effects of the substrate temperature and oxygen gas pressure on the formation and quality of these films were studied. Films deposited at a substrate temperature of 800 °C and an oxygen pressure around 0.23 mbar…
We have measured the photon-energy dependence of the $\mathrm{O}1s2s2s$ and $\mathrm{O}1s2s2p$ resonant Auger lines at the $\mathrm{O}K$ edge of NiO. The transition from the Raman-like regime, where these features are observed at constant binding energy, to the Auger regime, where they appear at constant kinetic energ…
High molecular weight carboxylated polybutadienes (cPBDs) with number-average molecular weight (Mn) from 98,000 to 200,000 and carboxylic acid (COOH) contents of 0.5–10 mol % were successfully synthesized through hydrocarboxylation of polybutadienes (PBDs) at temperatures of 140–150°C using PdCl2(PPh3)2 and SnCl2 · 2H…
In an attempt to view the onset of urea denaturation in ribonuclease we have collected X-ray diffraction data on ribonuclease S crystals soaked in 0, 1.5, 2, 3, and 5 molar urea. At concentrations above 2 M urea, crystals were stabilized by glutaraldehyde crosslinking. We have also collected data on ribonuclease S cry…
The crystal and magnetic structures of the system YFe11−xCoxTi have been investigated by high-resolution neutron powder diffraction for the compositions x=1, 3, 7, and 9. All compounds have the ThMn12 type structure, with space group symmetry I4/mmm. The distribution of the atoms over the independent crystallographic…