Materials Literature
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The present work reports an investigation of the influence of the radial spacing between cathodes on the iron sintering process by hollow cathode electrical discharge, with surface enrichment of the alloying elements Cr and Ni. Pressed cylindrical samples of 9.5 mm diameter and density of 7.0 ± 0.1 g/cm³ were prepared…
The susceptibility of a duplex stainless steel UNS S31803 to thermal embrittlement at 475 °C was evaluated by means of mechanical tests (impact energy and hardness), magnetic measurements (hysteresis and thermomagnetic analysis) and scanning electron microscopy. The results show that the material undergoes severe embr…
Two new one-dimensional single azide-bridged metal(II) compounds [[M(5-methylpyrazole)4(N3)]n](ClO4)n(H2O)n [M = Co (1a), Ni (2a)] were prepared by treating an M(II) ion with stoichiometric amount of sodium azide in the presence of four equivalents of the 3(5)-methylpyrazole ligand. The isostructural compounds 1a and…
The preparation of spherical phosphor europium-doped yttrium oxide (Y 2 O 3:Eu) particles using a copolymer of N -isopropylacrylamide (NIPAM)] and acrylic acid (AAc) is described. The resulting phosphor particles have smaller particle diameters (<0.1 μm) compared to both commercial Y 2 O 3:Eu phosphors and spherical p…
Abstract A novel method of protein encapsulation is proposed. Preformed protein aggregates are covered with polyelectrolyte layers by means of layer‐by‐layer adsorption. The polyelectrolyte membrane prevents protein leakage out of the capsule. Using chymotrypsin as a model enzyme the capsule wall selective permeabilit…
Impregnating the cores of triblock-copolymer nanotubes with Fe2O3 renders them superparamagnetic. The resultant polymer/Fe2O3 hybrid nanofibers (see TEM image) have interesting properties in magnetic fields. The nanofibers align themselves in the magnetic-field direction, and mixtures of the nanofibers and nanotubes u…
The crystallization behavior of organometallic‐precursor‐derived amorphous Si‐C‐N ceramics was investigated under N 2 atmosphere using X‐ray diffractometry (XRD), transmission electron microscopy (TEM), and solid‐state 29 Si nuclear magnetic resonance (NMR) spectroscopy. Amorphous Si‐C‐N ceramics with a C/Si atomic ra…
Three novel Si‐C‐B‐N ceramic compositions, namely Si 2.9 B 1.0 C 14 N 2.9 , Si 3.9 B 1.0 C 11 N 3.2 and Si 5.3 B 1.0 C 19 N 3.4 , were synthesized using the polymer‐to‐ceramic transformation of the polyorganoborosilazanes [B(C 2 H 4 Si(Ph)NH) 3 ] n , [B(C 2 H 4 Si(CH 3 )NH) 2 –(C 2 H 4 Si(CH 3 )N(SiH 2 Ph))] n , and […
The mechanical properties of ceramic foams obtained through a novel process that uses the direct foaming and pyrolysis of preceramic polymer/polyurethane solutions were investigated. The elastic modulus, flexural strength, and compressive strengths were obtained for foams in the as‐pyrolyzed condition; values up to 7.…
The half-metallicity of ${\mathrm{CoS}}_{2},$ important for its possible use in spintronic applications, is investigated by means of density functional full-potential linearized augmented plane wave calculations within both the local spin-density approximation (LSDA) and the generalized gradient approximation (GGA). I…
Porous silicon oxycarbide (SiOC) ceramics in particular bulk and cellular structures are produced via polymer pyrolysis. By using optimal pyrolysis parameters (i.e., heating rate, maximum temperature) the addition of either solid fillers or chemically active additives is efficient in preventing the collapse of pore st…
Motivated by recent experiments on the organic superconductor $λ-(BETS)_2FeCl_4$ we study the Jaccarino-Peter effect (JPE), the earliest example of magnetic-field-induced superconductivity, from the point of view of current-density-functional theory. It is found that both Meissner (diamagnetic) and Pauli (paramagnetic…
We show that current localization in polycrystalline varistors occurs on paths which are, usually, in the universality class of the directed polymer in a random medium. We also show that in ceramic superconductors, voltage localizes on a surface which maps to an Ising domain wall. The emergence of these manifolds is e…
We derive and analyse the equation of motion for the spin degrees of freedom within time-dependent spin-density-functional theory (TD-SDFT). Results are (i) a prescription for obtaining many-body corrections to the single-particle spin currents from the Kohn-Sham equation of TD-SDFT, (ii) the existence of an exchange-…
We have studied tunneling of electrons into multiwall carbon nanotubes (NTs) in NT-gold and NT-NT junctions, the latter created by atomic force microscope manipulation. The tunneling conductance goes to zero as the energy (temperature and bias) is reduced, and the functional form is consistent with a power law. The ex…
This paper reviews the work made by the group of the present author on the effect of impurities on the kinetics of crystal growth in solutions. The impurity effect is here discussed in the light of the model proposed by Kubota and Mullin [J. Crystal Growth, 152 (1995) 86], in which impurities are assumed to be adsorbe…
In this study, high-quality ZnO:Al (ZAO) films were prepared by using dc reaction magnetron sputtering technology. The effect of Al doped in ZnO films on electrical and optical properties and its scattering mechanism were discussed in detail. The results showed that Al2O3 could be effectively removed by controlling ox…
Abstract The perovskite‐like manganites R 1− x A x MnO 3 , where R is a trivalent rare earth or Y and A is a divalent alkaline earth element, are characterized by a strong interplay of magnetism, electric transport and crystallographic distortion. At doping levels 0.15 < x < 0.45 the materials exhibit colossal m…
Pressing environmental and economic concerns dictate the need to develop new synthetic macromolecules based on renewable resources. The vast majority of existing materials are based on non-renewable fossil resources that will eventually be extinguished. Manufacturing synthetic polymers and disposal by incineration pro…
Thermal analysis involves a dynamic phenomenological approach to the study of materials by observing the response of these materials to a change in temperature. This approach differs fundamentally from static methods of analysis, such as structural or chemical analyses, which rely on direct observations of a basic pro…