Materials Literature
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This paper forms part VI in the series of the crystal structures of hydrophobic amino acids. A low-temperature form (120 K) of dl-norleucine (2-aminohexanoic acid, C6H13NO2), has been solved and refined in the space group C2/c. Molecular packing and cell parameters correlate very well with those proposed for the β-for…
FeN materials exhibiting high moment, low coercivity and small magnetostriction have previously been reported. Zr has been known to reduce the magnetostriction in other Fe alloys. The criteria for an ideal recording head pole material as well as shields for magnetoresistive sensors include high moment, low coercivity,…
We report the observation of Raman scattering from a vibration mode with frequency of 320 cm−1 and its higher-order harmonics in silicate glasses doped with selenide semiconductor nanocrystals such as CdSe and ZnSe. Comparison with Raman spectra of glasses and alkali halides doped with Se suggests that these modes are…
The electric-field response of ${\mathrm{CdS}}_{0.44}$${\mathrm{Se}}_{0.56}$ quantum dots in glass is studied as a function of particle size using electroabsorption spectroscopy. Up to six quantum-size levels can be observed in the data. The evolution of the transitions through many particle sizes provides evidence fo…
The thermodynamic and photochemical stability of Ga2O3–GaAs interfaces fabricated using in situ multiple-chamber molecular beam epitaxy has been investigated. The Ga2O3 films were deposited on clean, atomically ordered (100) GaAs surfaces using a molecular beam of gallium oxide. Thermally induced degradation of electr…
In the framework of classical dielectric theory, the hemispherical geometry is studied. Calculations on surface modes are carried out for isolated Drude-like hemispheres. The convergence of the results with respect to the number of coupled terms in the expressions of the potential is discussed. The electron-energy-los…
Colloidal suspensions aging under gravity have long been known to spontaneously separate into layers. We demonstrate through flow visualization experiments that a lateral temperature gradient as small as $10\mathrm{mK}/\mathrm{cm}$ can be responsible for such stratification and that strata correspond to a stack of con…
The materials incorporated into molten carbonate fuel cells (MCFC) have remained unchanged over the past 20 years. Materials selection is dominated by the need to satisfy performance, cost and stability criteria in the aggressive environment provided by the molten carbonate electrolyte. Accordingly, materials developm…
Tetrahedrally bonded, metastable zinc-blende single-crystalline, single-phase MnS was grown by molecular-beam epitaxy on ZnSe buffer layers grown on GaAs(100) substrates. The interface between MnS and ZnSe was studied by transmission electron microscopy and x-ray photoelectron spectroscopy. The valence-band discontinu…
In this article, NiFe2O4 nanosolids are prepared by compacting nanoparticles, synthesized by the coprecipitation method, under different pressures. The variations of structure and interface states of the NiFe2O4 nanosolids with compacting pressures are studied by x-ray diffraction and electronic spin resonance (ESR).…
We investigated the magnetization of the ultrafine cadmium ferrite particles formed during the coprecipitation method and discussed the origin of enhanced magnetization based on the magnetic properties. A transmission electron microscopy micrograph shows aggregation of fine particles having two kinds of shapes, fibrou…
Lithium mobility in has been followed by NMR and impedance spectroscopies. From this analysis, three stages have been distinguished. (1) Below 230 K, lithium occupies preferentially the octahedral sites of the NASICON structure. (2) Between 230 and 330 K, a low correlated and thermally activated lithium motion, with ,…
The entropy of tightly bent DNA is investigated in a variety of problems: closure probabilities, hairpin formation, nicked coils, plectonemic supercoiling, all in states with liquid-crystalline order. A new semiclassical method is presented for deriving the Green function of a tightly curved wormlike chain. Precise es…
Abstract In diesem Übersichtartikel werden chemische Aspekte der Herstellung von Oxiden nach Sol‐Gel‐Methoden näher beschrieben. Der Molekülchemie bieten sich in diesem Forschungsbereich interessante Möglichkeiten, wovon einige hier vorgestellt werden: 1) Vorstufen mit funktionellen Gruppen zur gezielten Herstellung v…
We present calculated electron excitation spectra for the LaM${\mathrm{O}}_{3}$ series (M=Cr-Ni) obtained within ab initio band-structure calculations for the real geometric and magnetic structures. The calculated results show good agreement with the experimentally obtained spectra. This suggests that the transition-m…
We have studied optical properties of oriented crystalline oligothiophene films on fused silica glasses. In crystalline films, the lowest absorption band of isolated molecules is split into a weak lower-energy band and a strong higher-energy band. The absorption spectra depend on the polarization of oblique incident l…
Amorphous silicon powders prepared by plasma-enhanced chemical vapor deposition, of 8--24-nm-sized particles agglomerated into larger aggregates were annealed in a reducing atmosphere to study the phase transformation behavior of these particles. High-resolution electron microscopy revealed a very rough surface, with…
The dynamics of optically generated excitations in a poly-(para)-phenylene--type ladder polymer has been investigated by means of femtosecond pump-probe as well as femtosecond luminescence up-conversion spectroscopy. In addition to the bulk emission a low-energy emission band assigned to physical aggregates is observe…
The electron field emission properties of the (111)1×1:H surface of natural semiconducting (p-type) diamond have been examined with simultaneous field emission and photoemission measurements. We find that the origin of the field emission is due to the electron tunneling from the valence band and show that the shape of…
When a chemical reaction such as \(A \rightleftharpoons B\) takes place simultaneously with a macrophase separation, mesoscopic structures similar to the patterns emerging during microphase separation appear. Since in a chemical system we can easily control the concentrations of the two species and reaction rates and…