Materials Literature
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Visible photoluminescence from porous silicon induced by infrared multiphoton excitation was observed at room temperature. Luminescence resulted from carrier excitations in the surface region of the sample. With the pump in the mid-infrared, excitation was effective only when the pump frequency was near resonance with…
A pyrrole ring of a porphyrin as an intramolecular proton donor: compound 1 (depicted below), with a deprotonated pyrrole ring, has been isolated as an intermediate in the oxidative transformation of the corresponding air-sensitive 21-telluraporphyrin into 21-oxaporphyrin.
Abstract Since the fundamental works of D. C. Bradley and R. C. Mehrotra, metal alkoxides have attracted attention because of the diversity of their low‐ and high‐molecular‐weight structures; they are also generating increasing interest as precursor compounds for solving technical materials problems. The understanding…
The potential energy surface (PES) of dissociative adsorption of H_2 on Pd(100) is investigated using density functional theory and the full-potential linear augmented plane wave (FP-LAPW) method. Several dissociation pathways are identified which have a vanishing energy barrier. A pronounced dependence of the potenti…
Semiquinone radical anions are prototype compounds for contact ion pair formation with metal counter cations. In order to investigate the still open question whether bulky alkyl groups can sterically interfere, diphenoquinone derivatives O=C(RC=CH) 2 C=C(HC=CR) 2 C=O with R = C(CH 3 ) 3 , CH(CH 3 ) 2 and CH 3 have bee…
Surface melting of extended chain crystals of a flexible segment containing liquid crystal polymer followed by quenching is shown to result in the epitaxial crystallization thereon of folded chain lamellae, i.e. self decoration. It is proposed that the initial extended chain lamellae form by chain folding in the mesom…
The commercially available closed-cell cellular plastic insulations are typically faced by gaseous impermeable metal foil to prevent transfer of gases from inside and from outside of the foam. Thus, the long-term aging properties of the foams will be different from the unfaced situation. In this research, it has been…
Creep tests of Hastelloy XR (a modified version of the conventional Hastelloy X) were carried out in simulated high-temperature gas-cooled reactor (HTGR) helium at 800, 900 and 1,000°C. The test results up to about 50,000 h showed no significant degradation in creep properties. The creep-rupture strength obtained thro…
2-Dicyanomethylene-1,3-dithiole-4,5-dithiolate (DCDD) has been prepared and used for the synthesis of transition metal complexes (Bu4N)2[M(DCDD)2], M = Ni, Cu, Zn. The redox properties of the nickel complex are similar to that of (Bu4N)2[Ni(dmit)2] (dmit: 1,3-dithiole-2-thione-4,5 dithiolate). Oxidation of (Bu4N)2[Ni(…
Abstract Sulfur/olefin copolymers are known as vulcanizing agents for rubber, but synthetic procedures for these materials are poor and there is little in the literature to relate the structure of the copolymer with the vulcanizate properties of the rubber. This study discusses a new suspension process for the prepara…
Thin polymer films were grown in radio frequency discharges containing C2H2. Actinometry revealed the trend in the plasma concentration of the CH species as a function of the operating pressure. The C–H bond density in the films, revealed by infrared analysis, was found to increase with the pressure of C2H2 in a simil…
ADVERTISEMENT RETURN TO ISSUEPREVArticleSyntheses and Characterization of Salts of N,N',N''-Tricyanoguanidinate Dianion (C4N62-) and the Observation of a Strong Nonlinear Optical Effect by Second Harmonic Generation from Na2C4N6.cntdot.H2ORamachandran P. Subrayan, Anthony H. Francis, Jeff W. Kampf, and Paul G. Rasmuss…
Investigations were made on the character of partial discharges (PD) in samples with a flat, air-filled, cylindrical cavity (height 0.1 mm) with one dielectric and one metallic wall. Images of discharge sequences in the cavity were recorded with a streak camera to determine the temporal and spatial development of the…
This text is an introduction to materials for non-majors. It covers metals, ceramics, polymers, semiconductors, glasses, superconductors, and fibers. There are many draw- ings and photos, but no exercises.
The compositional distribution in fcc Co-Mn magnetic thin films was studied in order to examine the possibility of a compositional separation, similar to that observed previously in hcp Co-Cr thin film magnetic recording media, occurring in an fcc alloy system. Spin-echo 59Co NMR study of Co75Mn25 films revealed a cha…
Phosphorescent light emission was investigated upon irradiation of WF6/H2/noble gas (Ar, Kr, Ne, Xe) mixtures by ArF excimer laser. The continuous, broadband phosphorescence emission originates from excited tungsten clusters. The phosphorescence ceased with increased Xe and H2 concentrations. Xe inhibits the formation…
Metastable ZrO 2 solid soutions containing up to 50 mol% PbO are formed at low temperatures from amorphous materials prepared by the hydrazine method: the tetragonal phase up to 30 mol% PbO and the cubic phase between 30 and 20 mol% PbO. The compound PbZrO 3 is formed at 615° to 690°C by transformation of c ‐ZrO 2 sol…
"Corvids feeding on carrion." Bird Study, 42(3), pp. 255–256
Fluorescent liquid crystalline side chain polymers were synthesized by copolymerization of a ferroelectric monomer and 5 per cent of various blue fluorescent naphthalic imide dye comonomers. Those copolymers were characterized by DSC, X-ray, GPC and optical microscopy. In favourable cases, fast switching fluorescent f…
The first analog smectic C* ferroelectric liquid crystal tunable filter designed for the application of wavelength-division-multiplexing optical communication systems is presented. The filter demonstrated has a switching time of /spl sim/400 μs, a tuning range of 14 nm at /spl lambda/=1550 nm, and a very small inserti…