Materials Literature
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We distinguish between two classes of the emeraldine form of polyaniline. Class I consists of materials prepared in the conducting, doped emeraldine salt (ES) form. They form substantially crystalline salts ES-I with the Pauli susceptibility, ${\ensuremath{\chi}}^{P}$, of a polaron lattice. Dedoping leads to an amorph…
We report the preparation of hard nitrogenated amorphous carbon films doped with as much as 20 at. % nitrogen. The nitrogen groups created by doping do not dramatically affect the film structure, but are found to break symmetry in ${\mathrm{sp}}^{2}$ domains causing the Raman-active G (``graphitic'') and D (``disorder…
Abstract The dye‐sensitized photo‐oxygenation of 3‐hydroxyestra‐1,3,5(10), 9(11)‐tetraen‐17‐one ( 8 ) gives a complex mixture from which only the 1,4‐endo‐peroxide 10 can be isolated in low yield. In contrast, the 3‐methoxy derivative 9 yields the C‐seco‐aldehyde 11 as a major product, suggesting that 1,2‐dioxetane is…
Single crystals of potassium hydrogen phthalate, commonly known as potassium acid phthalate (KAP) have been grown from aqueous solutions. The dielectric constant, loss tangent, specific heat and pyroelectric coefficient were determined as a function of temperature. Frequency response of the dielectric constant and tan…
Ba 0.9 Ca 0.1 TiO 3 ceramics have been fabricated using powders obtained by calcining mixtures of (i) BaCO 3 , CaCO 3 and TiO 2 and (ii) Ba 0.9 Ca 0.1 CO 3 and TiO 2 . The precursor Ba 0.9 Ca 0.1 CO 3 was prepared by a wet technique to ensure homogeneous mixing of Ba and Ca ions at the atomic level. DTA analysis of so…
The direct simulation Monte Carlo (DSMC) method has been modified to deal with the very small degree of ionization that occurs in the early stages of the 'communications blackout' phase of re-entry. The simplified model of the process assumes that the ionization is entirely a consequence of the reaction N + O yields N…
Rapid solidification by twin-roller quenching of iron-neodymium-boron alloys produces flakes which show a strong (00l) texture normal to their surface by x-ray diffraction. The strong crystal orientation is argued to be due to both directional solidification in a thermal gradient and uniaxial deformation of the solid…
The authors report the observation in partially converted precursor-route poly(p-phenylene vinylene) (PPV) of a strong light-induced luminescence fatigue. Increasing the conversion towards the fully conjugated polymer results in a loss of the quenching effect. They discuss exciton annihilation at photoexcited charged…
We have developed a new laser ablation and plasma hybrid technique for depositing thin diamond-like carbon (DLC) films on Si〈100〉 substrates at room temperature and at 110 °C with improved optical and mechanical properties. The technique involves coupling of laser energy (λ=0.308 μm, pulse duration=40 ns, and power 12…
Highly resolved emission, excitation, and absorption spectra of [Os(bpy)3]2+ doped into a single-crystal [Ru(bpy)3]X2 matrix with X = PF6, AsF6, SbF6 are presented for low temperatures (2 ˇ- T ˇ- 16 K). This comprehensive information allows a reliable spectroscopic identification of different sites and several electro…
The single‐crystal elastic moduli of natural samples of grossular (99.0 mol % Ca 3 Al 2 Si 3 O 12 ) and spessartite (94.8 mol % Mn 3 Al 2 Si 3 O 12 ) have been measured by Brillouin spectroscopy under ambient conditions. From these results the adiabatic bulk moduli K s and shear moduli μ are calculated to be K s = 168…
Abstract The effect of tetrabromobisphenol A diallyl ether (TBBA–DAE) on the flame retardancy of high impact‐strength polystyrene (HIPS) was studied and compared with that of tetrabromobisphenol A (TBBA). Experimental results showed that the flame retardancy of TBBA–DAE was superior to that of TBA by thermomixing in t…
The Read-Shockley treatment of small-angle grain boundaries in crystals is generalized to the case of quasicrystals. The dependence of the grain-boundary energy on the angle of mismatch between abutting quasicrystalline grains is calculated. It is found that, even for a symmetric tilt boundary in a quasicrystal, dislo…
Abstract The comparative study of thermal degradation for poly[3‐dimethyl(methacryloyloxyethyl)ammonium propanesulfonate] [poly(DMAPS)] was studied by various methods under different conditions. The reaction order, the activation energy, and the preexponential factor were evaluated from thermal gravimetric curves. The…
A simple model is introduced to describe the observed coexistence of gelation and phase demixing in atactic polystyrene solutions. It is shown that the multiple equilibria conditions for molecular clustering caused by physical cross linking can lead to a characteristic feature of the phase diagram. The condition is ex…
Ferroelectricity in ${\mathrm{Zn}}_{\mathrm{x}}$${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$Te was found from the temperature variation of the dielectric constant, and from the hysteresis loop. The Zn contents varied from 4% to 45%. No ferroelectricity was found in pure CdTe but all samples containing Zn had a…
We present a new type of localization phenomenon in a one-dimensional tight-binding model with a quasiperiodic potential ${\mathit{V}}_{\mathit{n}}$=tanh[Acos(2\ensuremath{\pi}\ensuremath{\omega}n)]/tanhA, where \ensuremath{\omega} is an irrational number. When A is small, the localization starts from the center of th…
Containerless undercooling in an electromagnetic levitation device was used to observe solidification velocities as a function of undercooling temperature for pure Ni and Cu-Ni alloys. In a limited temperature range, the results can be interpreted using current theories, provided the conditions for local equilibrium a…
A new type of halide glasses, based on coordination compounds of the chlorides, bromides and heavy metals have been proposed. The formation of the halide glasses and their property will be discussed on the basis of suggested sheme of cluster compound formation. The paper also deals with the fabrication of silver and t…
Scanning Deep Level Transient Spectroscopy (SDLTS) is a current SEM technique for the detection of the local distribution of deep level centres in semiconductors. The contribution deals with the physical foundations of the SDLTS technique and it discusses the demands on the instrumentation. The measurement practice is…