Materials Literature
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We have measured the velocity of a running crack in brittle single crystal silicon as a function of energy flow to the crack tip. The experiments are designed to permit direct comparison with molecular dynamics simulations; therefore the experiments provide an indirect but sensitive test of interatomic potentials. Per…
Large twist-angle grain boundaries in layered structures are often described by Scherk's first surface, whereas small twist-angle grain boundaries are usually described in terms of an array of screw dislocations. We show that there is no essential distinction between these two descriptions and that, in particular, the…
We briefly introduce hysteresis in spatially extended systems and the dynamic phase transition observed as the frequency of the oscillating field increases beyond a critical value. Hysteresis and the decay of metastable phases are closely related phenomena, and a dynamic phase transition can occur only for field ampli…
A previously unreported ferroelectric phase has been discovered in a highly homogeneous sample of PbZr0.52Ti0.48O3 by high-resolution synchrotron x-ray powder diffraction measurements. At ambient temperature the sample has tetragonal symmetry (at=4.037 Å, ct=4.138 Å), and transforms below ∼250 K into a phase which, un…
Electroconductive polychloroprene (CR)–polyaniline (Pani) composites were prepared by swelling the vulcanized rubber material in aniline followed by immersing the specimen in an aqueous solution of HCl containing ammonium persulfate as the oxidant. The results obtained from surface and volume conductivity, scanning el…
Based on the extensive experiments of Qin et al. on the effects of low molecular weight liquid-rubber diluents on the craze plasticity of polystyrene and the substantial toughening obtainable in certain ranges of temperature, strain rate, and diluent character, we examine in this article the various factors that limit…
The effects of SrTiO3 content on the electromagnetic properties and electromagnetic wave-absorbing characteristics of SrTiO3–epoxy composites were investigated. Also, the frequency dispersion behavior of the complex permittivity of composites was demonstrated. The complex permittivity and permeability were measured us…
PVC is often used in food packaging and blood bags. This study concerns mass transfers between plasticized PVC, having been subjected to a treatment, and liquid food or food simulants. The treatment reduces the diffusion of the plasticizer and the influence of some factors of this processing are investigated. A mathem…
CO2 sorption and diffusion in poly(3-hydroxybutyrate) and three poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymers were investigated gravimetrically at temperatures from 25° to 50°C and pressures up to 1 atm. The sorption behavior proved to be linear for all the copolymers studied. An additional set of measuremen…
Blends of acrylonitrile butadiene rubber (NBR) and poly(ethylene-co-vinyl acetate) (EVA), with varying proportions of the components, were vulcanized using different crosslinking systems, namely, sulfur (S), dicumyl peroxide (DCP), and a mixed system (S + DCP). Mechanical properties, such as stress–strain behavior, te…
Poly(ethylene terephthalate)-co-poly(ethylene DDP)s [PET-co-poly(ethylene DDP)s], were synthesized by charging 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOP), itaconic acid, terephthalic acid, and ethylene glycol in one reactor to conduct the microaddition reaction (using H2PtCl6 as catalyst), esterification…
Bis(amides) of the type CH(3)CONH(CH(2))(n)()NHCOCH(3) (n = 2, 4, or 6) react with a range of manganese(II) and cobalt(II) salts to produce polymeric "framework" arrays, five of which have been studied by X-ray crystallography. Hexamethylenebis(acetamide) (HMBA) forms the compound [Co(HMBA)(3)](CoCl(4)).2EtOH in which…
The effects of radio-frequency-excited oxygen and hydrogen plasmas on gold island films with adsorbed CN -, thiophenate, or p -nitrobenzoate ions have been investigated by surface-enhanced Raman spectroscopy (SERS). An oxygen plasma caused oxidation of adsorbed CN - to Au(CN) 4 -, and there was evidence of oxidation o…
An internally circulating fluidized-bed (ICFB) reactor (i.d. eff = 1.9 cm, H riser = 10 and 20 cm, respectively) was applied to investigate the catalytic partial oxidation of methane to synthesis gas over Ni/α-Al 2 O 3 (Ni loading, 1 and 5 wt %; particle diameter, 71−160 and 250−355 μm). The experiments were performed…
The entire history of chemistry bears witness to the extraordinary importance of the phenomena of solubility. With the discovery of conducting polymers in the late 1970s, there was genuine interest...
Photoresponsive asymmetrically organized systems based upon small unilamellar dihexadecyl phosphate (DHP) vesicles were constructed by entrapping high concentrations of potassium ion within the vesicular aqueous core and incorporating either an amphiphilic trans -azobenzene-containing phosphate monoester or an amphiph…
Neutron diffraction data presented in this paper demonstrates the relevance of lattice displacement above TC, in our understanding of the evolution of the crystal structure with temperature in the layered CMR manganite La1.2Sr1.8Mn2O7. The anomalous temperature behavior of thermal diffuse scattering (TDS) in La1.2Sr1.…
We formulate the theory of the perturbation caused by an adsorbate upon the substrate lattice in terms of a local modification of the interatomic potential energy around the adsorption site, which leads to the relaxation of substrate atoms. We apply the approach to CO chemisorption on close-packed metal surfaces, and…
An experimental method based on the Landau-Zener model was developed to measure very small tunnel splittings in molecular clusters of eight iron atoms, which at low temperature behave like a nanomagnet with a spin ground state of S = 10. The observed oscillations of the tunnel splittings as a function of the magnetic…
A technique for determining the deep-center parameters from the relaxational delay of avalanche breakdown of a p-n junction is investigated. The method implemented does not impose any restrictions on the relation between the concentration of the deep centers and that of the dopant impurities and can be used in those c…