Materials Literature
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Special features of atomic vacancies in oxides of the perovskite family have been studied within the framework of the Green function method. It has been shown that, in accordance with experiments, the oxygen vacancy has both shallow and comparatively deep levels corresponding to different charge states. The single-cha…
Ellipsometric measurements of a nematic drop spreading on a rough surface are reported. The thickness profile of the drop shows two typical lengths belonging to the microscopic and to the mesoscopic scales (a few tens and some hundreds of \AA{}, respectively). No intermediate thicknesses are observed during the spread…
In this letter we report on the growth of thick films of magnetoresistive La2/3Sr1/3MnO3 films using a spray printing technique. The as-prepared films display a room-temperature magnetoresistance of 0.0012%/Oe in the 1 kOe field region. We will show that this field sensitivity is high enough to fabricate devices which…
Fungal fimbriae are surface appendages that were first described on the haploid cells of the smut fungus, Microbotryum violaceum. They are long (1-20 microm), narrow (7 nm) flexuous structures that have been implicated in cellular functions such as mating and pathogenesis. Since the initial description, numerous fungi…
The presence of interstitial oxygen molecules in glassy ${\mathrm{SiO}}_{2}$ has been demonstrated directly by 1064.1 nm $({\ensuremath{\nu}}^{\ensuremath{'}\ensuremath{'}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0)\ensuremath{\rightarrow}({\ensuremath{\nu}}^{\ensuremath{'}}\phantom{\rule{0ex}{0ex}}=\phantom…
A recently proposed computational scheme based on local increments has been applied to the calculation of correlation contributions to the cohesive energy of the CaO crystal. Using ab-initio quantum chemical methods for evaluating individual increments, we obtain 80% of the difference between the experimental and Hart…
The optical properties of N${\mathrm{d}}_{0.7}$S${\mathrm{r}}_{0.3}$Mn${\mathrm{O}}_{3}$ thin films have been studied over a broad spectral range, at temperatures down to 15 K and magnetic fields up to 8.9 T. A large transfer of spectral weight from high energy to low energy occurs as this material is cooled into the…
InAs nanocrystal quantum dots have been prepared via colloidal chemical synthesis using the reaction of InCl3 and As[Si(CH3)3]3. Sizes ranging from 25 to 60 Å in diameter are produced and isolated with size distributions of ±10%–15% in diameter. The nanocrystals are crystalline and generally spherical with surfaces pa…
We report the first measurements of the glass transition temperature ${T}_{g}$ for thin freely standing polystyrene (PS) films. We have used Brillouin light scattering to measure ${T}_{g}$ for freely standing films of different thicknesses. We find that ${T}_{g}$ decreases linearly with film thickness $h$ for $h\ensur…
The magnetoresistance (MR) and the field dependent magnetization have been systematically examined in the low temperature ferromagnetic metallic state of single crystal and polycrystalline ${\mathrm{La}}_{2/3}{\mathrm{Sr}}_{1/3}{\mathrm{MnO}}_{3}$. We find that the intrinsic negative MR in single crystal is due to the…
A new compound floatation agent for graphite is described. It is very effective on the floatation of cryptocrystalline graphite. The structure and composition of the new floatation agent are studied by using Raman and infrared spectra.
Five prototypic SP-100 thermoelectric cells were put on test in vacuum at prototypic temperatures. Their thermal and electrical performances were characterized with 200, 300, 400, and 500°C temperature gradients across the cell. The latter was representative of prototypic operating conditions with a 1050°C hot-side te…
Sintering behaviors of (Pb, La)(Zr, Ti)O 3 (PLZT 8/65/35) ceramics in ozone atmosphere and their ferroelectric properties were investigated. In the early stage of sintering, the presence of ozone prompted the growth of crystallites and grains, and promoted densification. Ozone content dependence of these structural fa…
An investigation of the approach to the melting point in CsPbCl3 by 133Cs NMR and Gd3+ EPR measurements is reported. A pretransitional phenomenon is observed with the two techniques. The evolution with temperature of the NMR and EPR linewidths gives some information on the dynamics around the solid-liquid transition.
In this work we shown that in uniformly illuminated samples a nonlinear dependence of the pyroelectric current on the radiation intensity is observed when the heat flux density reaches a critical value. It is found that the observed frequency variations and the pyrocurrent relaxation behaviour are different when diffe…
Two new polyphosphazenes, poly(4-maleimidophenoxy/phenoxy)phosphazene and poly(4-phthalimidophenoxy/phenoxy)phosphazene, were prepared and used to toughen a PMR polyimide designated LaRC TM RP46. These toughened polyimides were evaluated as thin films with a 0–40 wt% range of polyphosphazene to polyimide. The structur…
Abstract Many sugars occur in several crystalline and in an amorphous form. The glass transition temperatures of isomalt and its components and the enthalpies of fusion are reported. Amorphous sugars are extremely hygroscopic and sorb large amounts of water. This gives rise to supersaturated sugar solution, from which…
A high-resolution optical imaging system and custom-designed image analysis software are used to make surface roughness measurements for deuterium-tritium (D-T) solid layers, equilibrated inside a 2-mm-inside-diameter re-entrant copper cylinder. Several experiments are performed that yield D-T layer thicknesses of bet…
The general compositions Nam−1.5Bi2.5NbmO3m+3 (2<mm<m5), which can be viewed as a solid solution between a bismuth layer-structured ferroelectric (BLSF), Na0.5Bi2.5Nb2O9 [NBN], and a perovskite compound, NaNbO3, as studied. They form layer-structured ferroelectrics for layer-numbers m=2, 3, 4 and 5 and are new BLSF. T…
On the basis of a conventional Cockcroft–Walton (C–W) cascade rectifying circuit, an expression is derived for the fundamental harmonic of ripples due to asymmetry of driving voltage in a symmetrical C–W circuit. The expression is validated from good agreement with experimental results of both a low-voltage model circ…