Materials Literature
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The correlation between the spin polarization of the tunneling current in ferromagnet/Al2O3/Al tunnel junction experiments and the magnetic moment in ferromagnets has been a mystery [Phys. Rev. B 16, 4907 (1977) and Phys. Rep. 238, 173 (1994)]. In this study, an attempt is made to explain this correlation. By assuming…
The ab initio linear muffin-tin-orbital formalism and the semiempirical method of the intermediate neglect of the differential overlap based on the Hartree-Fock formalism are combined for the study of the hole polarons (a hole trapped nearby the cation vacancy) in a cubic phase of ${\mathrm{KNbO}}_{3}$ perovskite crys…
A resonant method based on a tunnel-diode oscillator for precision measurements of relative impedance changes in materials is described. The system consists of an effective self-resonant LC tank circuit driven by a forward-biased tunnel diode operating in its negative resistance region. Samples under investigation are…
Continued innovations in the polymer industry have made polymer surface modification methods a subject of intense research. The importance and necessity of surface modification of plastics are explained, and the advantages of physical surface treatments over the less-sophisticated chemical methods are outlined. Curren…
This article compares the cure behavior and properties of phthalonitrile polymers derived from three different monomers, namely, 4,4′-bis(3,4-dicyanophenoxy)biphenyl, 2,2-bis[4-(3,4-dicyanophenoxy)phenyl]hexafluoropropane and 2,2-bis[4-(3,4-dicyanophenoxy)phenyl]propane. Rheometric measurements with monomer melt in th…
A range of methods for the detection of barium carbonate contaminant in barium titanate powder has been assessed, namely: X‐ray diffraction (XRD), scanning electron microscopy (SEM), with EDS‐X‐ray microanalysis, Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), gas chromatography (GC)…
Transparent and conductive thin films of multicomponent oxides composed of binary and/or ternary compounds with varied chemical compositions have been prepared by rf or dc magnetron sputtering. Transparent conducting oxide (TCO) films were prepared in multicomponent oxides composed of ZnO, SnO2, Ga2O3, or MgO combined…
Thermal decomposition of boehmite and bayerite has been studied by X-ray diffraction and by NMR and IR spectroscopies. Coordination and site distortion of Al polyhedra have been estimated by 27 Al NMR spectroscopy while IR optical properties of transitional aluminas, η-, γ-, δ-, and θ-Al 2 O 3 were derived from IR nea…
Abstract Poly(lactide) (PLA), a biodegradable aliphatic polyester with excellent properties for different polymer applications, has been used mostly in the biomedical field, mainly because of its high price, resulting from expensive polymerization and purification techniques. Although this polymer can play a major rol…
Arsenic contamination of groundwater has recently commanded widespread public attention. Under many conditions, arsenic, and certain other environmentally relevant toxic metals such as chromium, exist in nature as oxyanions. Selective binding of anions is one of the most challenging problems in chemistry, biology, and…
The melting behavior of isothermally crystallized poly(butylene succinate) (PBS) has been investigated using differential scanning calorimetry (DSC) and wide-angle X-ray analysis. The samples crystallized between 80°C to 100°C show middle endotherm at the position just before the high exotherm, while the others under…
A high‐pressure burner rig was developed to evaluate the response of chemical‐vapor‐deposited SiC material during exposure to simulated gas turbine combustor conditions. Linear weight loss and surface recession rates of SiC were observed in both fuel‐lean and fuel‐rich gas mixtures. This response was shown to result f…
Internal stresses in tension and compression in an extruded and artificially aged Mg-7.7at.% Al alloy have been determined by in-situ neutron diffraction. Measurements were made on grains having the c axis normal to, parallel to and at 62° from the stress axis, and on the reinforcing phase. The results are consistent…
In combustion environments, volatilization of SiO 2 to Si‐O‐H( g ) species is a critical issue. Available thermochemical data for Si‐O‐H( g ) species were used in the present study to calculate boundary‐layer‐controlled fluxes from SiO 2 . Calculated fluxes were compared to volatilization rates of SiO 2 scales grown o…
The mechanisms of plastic deformation in nanocrystalline Ni are studied using three-dimensional molecular-dynamics computer simulations for samples with mean grain sizes ranging from 3 to 12 nm under uniaxial load at finite temperatures. At the lower limit of this size range, we observe a plastic regime controlled by…
Biocorrosion processes at metal surfaces are associated with microorganisms, or the products of their metabolic activities including enzymes, exopolymers, organic and inorganic acids, as well as volatile compounds such as ammonia or hydrogen sulfide. These can affect cathodic and/or anodic reactions, thus altering ele…
Metastable thermodynamic states are frequently encountered in pharmaceutical systems, in the intentional or unintentional creation of supersaturation, in the crystallization of desired solid-state modifications, and in the control of solid-phase conversions during isolation, manufacturing, storage, and dissolution.1-4…
An overview of the literature together with selected authors' data on thermal and thermo-oxidative decomposition of commercial aliphatic nylons (nylon 6, nylon 7, nylon 11, nylon 12, nylon 6.6, nylon 6.10, nylon 6.12) is presented. Despite the high level of research activity and the large number of publications in the…
Single crystal Ag nanorods and elegant highly ordered dendriticsupramolecular nanostructures (see Figure) of Ag nanoparticles have been prepared via a novel ultraviolet photoreduction technique at room temperature using poly(vinylalcohol) (PVA) as protection agent. The concentration of both the PVA and AgNO3 play a si…
The full phonon dispersion relations of lead titanate and lead zirconate in the cubic perovskite structure are computed using first-principles variational density-functional perturbation theory, with ab initio pseudopotentials and a plane-wave basis set. Comparison with the results previously obtained for barium titan…