Materials Literature
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A model for the dynamical behavior of a hysteretic elastic system is introduced and studied numerically. This model consists of a chain of hysteretic elastic elements. Each elastic element is a spring with properties that depend on an Ising-like state variable having Brownian dynamics in an energy landscape with struc…
The spin-crossover complex [FeL2](BF4)2 undergoes a LIESST transition at 30 K on irradiation; the structures of the low-spin ground and high-spin metastable states at this temperature are presented.
The temperature dependence of electrical properties for SrBi2Ta2O9 thin film capacitors with platinum electrodes (Pt/SBT/Pt) on silicon wafers was studied from 10 to 300 K. With a decrease in temperature from 300 to 200 K, the remanent polarization of the thin films shows about an 11% reduction from its 300 K value; h…
The syntheses, structures, and characterization of four new lead(II)-tellurium(IV)-oxide halides, Pb(3)Te(2)O(6)X(2) and Pb(3)TeO(4)X(2) (X = Cl or Br) are reported. The materials are synthesized by solid-state techniques, using Pb(3)O(2)Cl(2) or Pb(3)O(2)Br(2) and TeO(2) as reagents. The compounds have three-dimensio…
We report the magnetic properties and magnetoresistance (MR) in small iron oxide (Fe3−xO4 and Fe3O4) cluster assemblies. Half-metallic Fe3O4 cluster assembly with grain size of 10–15 nm is shown to exhibit a MR value of about 8% at T=30 K and a peak around the Verwey transition temperature Tv=115 K which is a little l…
The compound Cu3(dpa)4Cl2, 1 (dpa = the anion of dipyridylamine), which was first synthesized and characterized in 1990, has been structurally characterized in three new crystal forms having Cu...Cu separations of 2.47-2.49 A. Its magnetic properties have been studied fully. Reaction of Cu3(dpa)4Cl2 with 2 equiv of si…
Polypyrrole (PPy) nanotubes were synthesized using the pores of track-etched polycarbonate membrane as a template. Its size depends on the pore diameter of template, range from 50 to 200 nm. Direct I–V measurements of PPy nanotube (diameter of 120 nm) deposited on Au were done using a metal-coated tapping-mode atomic-…
Highly-ordered arrays of Ni-filled carbon nanotubes have been fabricated by a second-order template method. First, an array of aligned carbon nanotubes was generated in a porous alumina membrane by catalytic pyrolysis of acetylene. The desired material, such as nickel, was then filled into the aligned carbon nanotubes…
We report the first direct observation of the ultrafast electronic relaxation and coherent vibrational oscillation of strongly interacting gold nanoparticle aggregates measured by femtosecond laser spectroscopy. The electronic relaxation, reflected as a fast decay component with a time constant of 1.5-2.5 ps, becomes…
Abstract A series of six polyurethanes were prepared to study the effect of silicon chain extender structure on properties and morphology of siloxane–polyurethanes. Polyurethanes were prepared by a two‐step bulk polymerization without a catalyst. The soft segment of the polyurethanes was based on an 80:20 (w/w) mixtur…
Abstract Polymer microspheres are obtained by the dropwise addition of a precipitant, containing a polymeric stabilizer, into a polymer solution, containing a polymeric stabilizer. The polymer and stabilizer concentrations, the stirring speed, and the precipitation temperature determine the size and size uniformity of…
Many-body levels of optically excited and multiply charged InAs nanocrystals are studied with the semiempirical tight-binding model. Single-particle levels of unstrained spherical InAs nanocrystals are described by the ${\mathrm{sp}}^{3}{d}^{5}{s}^{*}$ nearest-neighbor tight-binding model including spin-orbit coupling…
The electrochemical properties of individual multiwall carbon nanotubes (MWNTs) coated with an amorphous carbon layer are reported. MWNTs were etched at potentials more positive than 1.7 V vs. Ag/AgCl (3 M NaCl) in an aqueous 0.1 M KCl electrolyte solution. The logarithm of etching rate was proportional to the applied…
Abstract The mechanical and dynamic mechanical properties of thermoplastic polyurethane (TPU) elastomers reinforced with two types of aramid short fibers, m ‐aramid (Teijin‐Conex) and copoly( p ‐aramid) (Technora), were investigated in this study with respect to the fiber loading. In general, both types of composites…
The rate of addition of the internal phase influences the catastrophic inversion of emulsions in the direction of change from abnormal to normal morphology. At a low addition rate, the inversion takes place after a small amount of the internal phase is added, and it happens through the occurrence of multiple emulsion…
The stirring intensity has a complex effect on the catastrophic inversion of emulsions in the direction of change from abnormal to normal morphology. At both low and high stirring energy, the inversion takes place early, after a low amount of the internal phase is added and through the occurrence of a multiple emulsio…
The adsorption properties of various water-soluble aromatic molecules (p-nitrophenol, p-nitroaniline, m-nitrophenol, p-chlorophenol and phenol), with CD-HMS, a new class of cyclodextrin-containing materials with uniform framework mesoporosity, has been investigated. The adsorption isotherms, uptake kinetics and distri…
Alternating electrostatic deposition of poly(amic acid) salts and poly (allylamine hydrochloride) (PAH) followed by heat-induced imidization yields ultrathin, gas-selective polyimide membranes on porous alumina supports. These membranes are appealing because of the stability and selectivity of polyimides and the fact…
The feasibility of ultrasound-induced in situ radical formation in liquid carbon dioxide was demonstrated. The required threshold pressure for cavitation could be exceeded at a relatively low acoustic intensity, as the high vapor pressure of CO2 counteracts the hydrostatic pressure. With the use of a dynamic bubble mo…
Polymer/carbon nanotube films have been formed by the alternate adsorption of the polyelectrolyte poly(diallyldimethylammonium chloride) and single walled carbon nanotubes (SWNT) onto substrates. Atomic force and scanning electron microscopies indicated that the adsorbed SWNTs were mostly in the form of 5−10 nm bundle…