Materials Literature
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The authors propose a consistent approach to the study of hole self-trapping and diffusion in ionic crystals based on the static quantum-chemical calculation of the self-trapping energy and adiabatic barriers or hole diffusion. The calculations made for MgO revealed the possibility that the hole is localized on one an…
Results of a study on internal stress, hardness, and structure of nitrogen-doped amorphous hydrogenated hard carbon films deposited by rf glow discharge from methane-nitrogen mixtures onto silicon substrate are presented. Films obtained for different N2 partial pressures (bias voltage Vb=−370 V and total pressure P=8…
Black and white images were projected onto n-type silicon (100) wafers during a photoelectrochemical etch to produce a color image that photoluminesces. The photoluminescence originates from a thin layer of luminescent porous silicon that is produced in the photoetch, and the colors that appear in the etched image ari…
Abstract Studies of the thermal and photodegradation of two commercial polymers, stabilized and unstabilized low‐density polyethylene (LDPE), show the effects of weathering in differential scanning calorimetry (DSC) curves. The shape and the size of the melting peak vary significantly in thermal aging and in accelerat…
Abstract Both sodium hydroxide solution of mercerizing strength and anhydrous methylamine are suitable pretreatments for enhancing the reactivity of cotton cellulose. Favorable results are achieved by maintaining the fiber material in the never‐dried state after the swelling treatment. Extraction by organic solvents i…
Abstract A fast electrochemical technique for the discrimination of one‐ and two‐electron mechanisms in the oxidative addition of alkylating agents (RX) to corrinato‐ and porphyrinatocobalt(I) ([Co I L]) is described. It is based on single‐scan voltammograms of [Co II L] in the presence of RX and variable amounts of t…
Abstract The socium cryptates of the macrobicyclic ligands 1–6 have been synthesized by direct macrobicyclisation or by stepwise procedures. They incorporate 2,2′‐bithiazole, 2,2′‐biimidazole, 2.2′‐bipyrimidine as well as 2,2′‐bipyridine units. Treatment of the sodium complexes with europium(III) chloride gave the cor…
An experimental electronic bandstructure of molybdenum disulphide has been determined from angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) measurements: polar-angle-dependent ARUPS at a photon energy of 21.2 eV allows the authors to obtain an approximate plot of dispersion parallel to the basal face whil…
We report a new photoluminescence process in epitaxial Si1−xGex layers grown on Si by rapid thermal chemical vapor deposition which we attribute to the recombination of excitons localized at random alloy fluctuations. This luminescence is characterized by saturation at very low excitation densities (≂100 μW cm−2), ver…
The synthesis of SmCo5 by the chemical reduction of Sm2O3 during mechanical alloying has been investigated using x-ray diffraction, electron microscopy, and magnetic measurements. The mechanical alloying of Sm2O3 with Co and Ca resulted in the formation of CaO and an amorphous Sm-Co phase. The SmCo5 phase formed durin…
Cathodoluminescence (CL) measurements made on natural zircon crystals are reported for the temperature range 45-300 K. Different combinations of excitation conditions used at various temperatures, coupled with information on the decay lifetimes of the emission features provided by modulation of the electron beam, enab…
The growth rate of diamond synthesized in an oxygen-acetylene flame has been measured in situ with an infrared pyrometer. During the growth, the sample’s emitted radiation intensity is modulated in time by interference phenomena in the growing diamond film, causing a periodic variation of the pyrometer’s apparent temp…
We demonstrate that ferroelectric liquid crystals are suitable for application in polymer-dispersed liquid crystal (PDLC) displays. The alignment of the liquid crystal can be controlled by mechanical shear during the polymerization-induced phase separation between the liquid crystal and the UV-curable adhesive which f…
Epitaxial MgO thin films were grown on (100) GaAs substrates by reactive rf magnetron sputtering. Coupled x-ray diffraction, off-axis φ scan, and transmission electron microscopy indicated in-plane alignment of the MgO film with the GaAs substrate such that MgO[100]∥GaAs[100]. PbTiO3 ferroelectric thin films, grown on…
Amorphous-to-crystalline and crystalline-to-amorphous transformations are triggered in GeSb thin films by irradiation with femtosecond and picosecond laser pulses. Phase changes are accompanied with optical contrast and therefore the feasibility of phase-change optical recording at ultrafast rates is demonstrated for…
The origin of strain-induced, modulated domain structures observed in epitaxial ferroelectric lead titanate thin films is discussed using a phenomenological total-energy calculation. Linear elasticity is used to account for the substrate contribution while a free-energy functional of the Landau-Ginzburg-Devonshire typ…
Small colloidal particulates (150 nm and below, in diameter) can be redirected specifically to the rabbit bone marrow following intravenous administration by coating their surface with the block co-polymer poloxamer-407, a non-ionic surfactant. The coated colloids are sequestered by the sinusoidal endothelial cells of…
Cathodoluminescence spectra of undoped and boron-doped diamond films are reported and are compared with each other. The dominant spectra feature of these samples is the broad luminescence bands centered around 2.83 and 2.32 eV in undoped and relatively heavily doped samples, respectively. Our result indicates that the…
Binary mixtures of suspended hard-sphere colloidal particles, radius ratio ${\mathit{R}}_{\mathit{B}}$/${\mathit{R}}_{\mathit{A}}$=0.58, were observed to undergo entropically driven freezing transitions into both the ${\mathit{AB}}_{2}$ and the ${\mathit{AB}}_{13}$ superlattice structures at different relative proport…
A new dispersion involving a polymer in low concentration with a cholesteric liquid crystal is reported. Two types of light modulators from these materials are described as a normal mode shutter which is opaque (light scattering) in the field-OFF state and transparent in the field-ON state and a reverse-mode shutter w…