Materials Literature
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We revisited the problem of the stability of the superconducting state in ${\mathrm{Rb}}_{x}{\mathrm{WO}}_{3}$ and identified the main causes of the contradictory data previously published. We have shown that the ordering of the Rb vacancies in the nonstoichiometric compounds have a major detrimental effect on the sup…
The intrinsic linewidth ${\ensuremath{\Gamma}}_{\mathrm{TA}}$ of the transverse acoustic phonon observed in the relaxor ferroelectric compound $\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}{)}_{0.8}{\mathrm{Ti}}_{0.2}{\mathrm{O}}_{3}$ (PMN-20%PT) begins to broaden with decreasing temperature around 650 K, nearly…
We have observed the $S$- and $Q$-branch Raman spectra of ${\mathrm{H}}_{2}$, HD, and ${\mathrm{D}}_{2}$ adsorbed at $85\mathrm{K}$ and pressures up to 8 atm on single-walled, carbon nanotubes (SWNT). Comparative data for ${\mathrm{H}}_{2}$ on graphite and ${\mathrm{C}}_{60}$ were also collected. Frequency-downshifted…
Oxygen-deficient SrFeO 3 - δ (0.02 < δ < 0.26) perovskites were prepared by soft-chemistry procedures, followed by annealing under different conditions, including high oxygen pressure. These materials contain Fe cations in the mixed Fe 3+ −Fe 4+ valence state. The samples were characterized by X-ray and neutron powder…
The metastable lifetime of the square-lattice and simple-cubic-lattice kinetic Ising models are studied in the low-temperature limit. The simulations are performed using Monte Carlo with Absorbing Markov Chain algorithms to simulate extremely long low-temperature lifetimes. The question being addressed is at what temp…
A solid-oxide fuel cell that operates at 500 °C (instead of 600 °C and higher), with lower material cost and better long-term stability, is presented. Its key piece is a cathode made of a silver/copper-doped bismuth vanadate (Ag-BICUVOX) composite, which reduces oxygen at lower temperatures and diminishes the resistan…
Nanocrystalline YVO 4:A (A = Eu 3+, Dy 3+, Sm 3+, Er 3+ ) phosphor films and their patterning were fabricated by a Pechini sol−gel process combined with soft lithography. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), atomic force…
The recently proposed artificial media with negative magnetic permeability and left-handed metamaterials are revisited at the light of the theory of artificial bi(iso/aniso)tropic media. In particular, the existence of bianisotropic effects in those materials is investigated, making use of an approximate model. Some u…
We compare the results of equilibrium and nonequilibrium methods to compute thermal conductivity. Using Sillinger-Weber silicon as a model system, we address issues related to nonlinear response, thermal equilibration, and statistical averaging. In addition, we present an analysis of finite-size effects and demonstrat…
Ion implantation is commonly used as a method to modify the surface or near-surface properties of materials and to improve their mechanical properties. In this paper, nanocrystalline diamond films, prepared by a microwave plasma enhanced chemical vapour deposition, were implanted using 110 keV nitrogen ions under a fl…
Current waveforms of first negative corona pulses have been measured in N 2 -SF 6 mixtures over a pressure range extending from 30 to 60 kPa and various overvoltages. Effects of changing cathode secondary electron emission were studied using a copper cathode coated by CuI and graphite. For a given set of experimental…
The dimensional and mechanical stability of materials is of paramount importance to their use in the everyday world where they may encounter a wide variation in temperature through design or by accident. Many polymers are processed at elevated temperatures so as to enable them to flow and be more amenable to fabricati…
2-Hydroxyl-1-naphthaldehyde has been utilized as a fluorigenic reagent for the determination of four aminoglycoside antibiotics namely: neomycin, tobramycin, amikacin and kanamycin, in pure form, in some pharmaceutical preparations and in biological fluids. The method is based on the reaction of the reagent with amino…
Ordered Ni-Cu alloy nanowire arrays embedded in the hexagonally ordered nanochannels of anodic alumina membranes (AAMs) were fabricated by electrodeposition. The x-ray diffraction, x-ray energy dispersion spectrum, scanning and transmission electron microscopy were utilized to characterize the Ni-Cu alloy nanowire arr…
Mechanical measurements, x-ray investigations, and optical microscopy are employed to characterize the interplay of chemical composition, network topology, and elastic response of smectic liquid crystalline elastomers (LCEs) in various mesophases. Macroscopically ordered elastomer films of submicrometer thicknesses we…
Radical additions of HPR2 (R = Et, Cy) onto alkenyl groups or nucleophilic substitution reactions on chlorosilanes by LiCH2PR2 (R = Me, Hex) are used to prepare first and second-generation alkylphosphine-containing dendrimers based on a polyhedral oligomeric silsesquioxane (POSS) core. The first generation dendrimers…
Transport property and mixed former effect studies on a new fast Ag+ ion conducting glass system: 0.7[0.75AgI : 0.25AgCl] : 0.3 [Ag2O : { xB2O3 : (1-x)MoO3} ], R C Agrawal, M L Verma, R K Gupta, R Kumar
Using hydrothermal techniques, two new compounds—strontium borate SrBO2(OH) and barium polyborate Ba3B6O9(OH)6—have been prepared. The structures of the title compounds were solved by single-crystal X-ray diffraction analysis. In the structure of SrBO2(OH), the Sr2+ ion is surrounded by eight oxygen atoms and the bora…
The cationic polymerizations of isobutylene (IB) initiated by the H 2 O/TiCl 4 in dichloromethane (CH 2 Cl 2 ) at −30 °C were carried out in the absence and presence of various external electron pair donors (EDs). Controlled polymerization with a slow polymerization rate and a narrow molecular weight distribution (MWD…
Nanosized copper oxide–zirconia particles containing 10–30 mol% of copper were prepared by using a precipitation technique in aqueous tetramethylammonium hydroxide solutions. Two methods, in situ (INS) and step-by-step (SBS), which differed in the time when the copper salt was introduced to the synthesis procedure, we…