Materials Literature
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The electrical band gap of porous silicon is determined from measurements of the reverse bias current of homojunction pn porous silicon diodes versus temperature, resulting in a value of 2.2 eV. This value is in good agreement with the value of 1.97 eV obtained from photo- and electroluminescence experiments.
Abstract The compatibility of blends of polyamide‐6/[styrene‐(ethylene‐butylene)‐styrene] triblock copolymer (SEBS) was enhanced with a compatibilizer, maleated SEBS, whose compositions were varied from 0 to 4 wt % of the blends. The maleated SEBS (MA‐g‐SEBS) was synthesized by reacting (grafting) maleic anhydride (MA…
A combination of scaled particle theory for fluids and a simple cell model for crystalline solids is used to study the freezing behaviour of a binary hard-sphere system. As the two kinds of sphere become increasing dissimilar, we find that the phase diagram changes from a spindle type to an azeotropic type, and then t…
Surface temperature images obtained by the ratioing of visible (5)D(2) and (5)D(1), emissions from a La(2)O(2)S:Eu phosphor coating are demonstrated. The visible phosphor emissions permit imaging with standard CCD cameras. Temperature resolution to 1 K is achieved over a temperature range of 193-293 K.
Abstract The degree of crystallinity and the disorder parameter in ramie fibers treated with various concentrations of aqueous NaOH solutions at room temperature (∼ 30°C) and at 0°C, respectively, have been analyzed by the wide‐angle x‐ray diffraction method of Ruland and Vonk. 9–11 The results appear to suggest the p…
Optimization was carried out for the recovery of microbiol poly(3-hydroxybutyrate) (PHB) from Alcaligenes eutrophus. This process involved the use of a dispersion made of sodium hypochlorite solution and chloroform. The dispersion enabled us to take advantage of both differential digestion by hypochlorite and solvent…
Photodiodes fabricated from conjugated polymers exhibit excellent sensitivity to visible-UV radiation. The photosensitivity increases with reverse bias voltage. The photoresponse of diodes fabricated from poly(3-octyl thiophene) is relatively flat in the visible and near UV; for wavelengths shorter than 550 nm, the ab…
Conducting filaments of polyaniline have been prepared in the 3-nanometer-wide hexagonal channel system of the aluminosilicate MCM-41. Adsorption of aniline vapor into the dehydrated host, followed by reaction with peroxydisulfate, leads to encapsulated polyaniline filaments. Spectroscopic data show that the filaments…
The crystal structure of NH3(CH2)4NH3PbCl4 at room temperature (RT phase) is determined by X-ray diffraction. The structural arrangement is of two-dimensional type, with ammonium alkylene chains located in between corner-sharing PbCl6 octahedra layers. The connection between the inorganic and organic parts of the stru…
The structure of NaLaIII(SO4)2.H2O consists of distorted Na-O6 octahedra, La-O9 complexes in the form of distorted tricapped trigonal prisms, and slightly irregular tetrahedral sulfate ions. All bond distances fall within normal limits. The sulfate ions manifest rigid-body behavior but this is not the case for either…
In silver-doped silicon, a photoluminescence band is observed with zero-phonon lines at 778.92, 779.85, and 784.31 meV, which is concluded to be associated with the spin-triplet and spin-singlet states of a bound exciton. The photoluminescence excitation spectrum of this defect, with the transitions to s-like electron…
Field emission from localized narrow bands above the Fermi level (${\mathit{E}}_{\mathit{F}}$) are obtained in two nanometer-scale systems: gold nanoclusters deposited on W support tips and nanotips that are W nano-scale protrusions formed on W support tips. The shift of localized bands was used as a probe of the tunn…
Electroluminescence (EL) in gold-coated porous silicon has been studied under pulse excitation. The room temperature EL is independent of ambient, unlike photoluminescence (PL). It decreases after 30 min annealing treatments, disappearing after about 480 °C, whereas the PL from either a similar or the same sample, obs…
The chemical oxidation of hydrogen-terminated silicon (111) surfaces in water was studied in situ with Fourier transform IR spectroscopy in the multiple total internal reflection mode. On the basis of measurements of the absorbance of the Si-H and Si-O-Si vibrations as a function of time it is concluded that reactions…
Structural and electrical properties of rf magnetron-sputtered Ba1−xSrxTiO3 thin films (x=0, 0.25, 0.5, 0.75, 1) on indium-tin-oxide-coated glass substrate were studied. The dense Ba1−xSrxTiO3 thin films sputtered from five different targets at the deposition temperature of 550 °C had individual orientations. The resu…
The paper deals with optical second-harmonic generation in a medium absorbing the second-harmonic radiation, and where phase matching between the fundamental and second-harmonic radiation is not necessarily achieved. We first take the waves to be in the form of traveling waves, and describe the damping of the fundamen…
We report x-ray photoemission, UV photoemission, and bremsstrahlung isochromat spectra of TiO with ordered vacancies in both Ti and O sublattices and of the series ${\mathrm{TiO}}_{\mathit{x}}$ (0.8x1.3) containing disordered Ti and O vacancies. The details of the electronic structure are discussed in comparsion to ba…
Novel compounds RE6Fe13X (X=Cu, Ag, Au, Zn, Cd, Hg) have been synthesized by arc melting (Cu, Ag, Au) or by reaction sintering (Zn, Cd, Hg), followed by heat treatment at 550 or 600 °C up to 350 h in evacuated silica capsules. From room temperature x-ray powder diffraction analyses the alloys were found to crystallize…
Absolute measurements of the photoabsorption coefficient of Mg, Al, and Si from 25 eV up to the ${\mathit{L}}_{3}$ absorption edge are presented. Transmission measurements were performed on free-standing thin films using a laser-produced plasma source. The surface oxide is corrected for by taking the ratio of the abso…
The sumrules for X-ray absorption and photoemission [Thole et al ., Phys. Rev. Lett. 68 (1992) 1943; 70 (1993) 2499] which relate the integrated signals of the magnetic circular and linear dichroism to the orbital magnetic moment and quadrupole moment are generalized to point group symmetry. The polarization dependenc…