Materials Literature
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The equilibrium oxygen chemical potential of mixed oxygen ion and electron conducting perovskites ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CoO}}_{3\ensuremath{-}\ensuremath{\delta}}$ was measured as a function of $\ensuremath{\delta}$ and x by high temperature oxygen coulometric titration. An almost…
We demonstrate that the electrical excitation of Er ions incorporated within the depletion layer of a p+−n+ Si diode allows one to simultaneously obtain efficient pumping of rare earth ions and a fast turnoff time of the electroluminescence signal. In fact it is found that during pumping, under reverse bias at the bre…
Two sources of room temperature visible luminescence are identified from SiO2 films containing ion beam synthesized Si nanocrystals. From a comparison of luminescence spectra and photoluminescence decay lifetime measurements between Xe+-implanted SiO2 films and SiO2 films containing Si nanocrystals, a luminescence fea…
The thermodynamic origin of disordered intergranular films commonly found in covalent ceramic materials is studied by molecular-dynamics simulation. Our studies show that all high-energy grain boundaries in a model covalent material, silicon, exhibit a universal amorphous structure, whereas low-energy boundaries are c…
Ab initio cluster methods are used to investigate vacancy-impurity complexes in diamond. We assign the 1.682 eV, twelve-line optical band to a vacancy-Si complex which has a very unusual, possibly unique structure with a Si atom at the center of a split vacancy. The method also successfully accounts for the 1.945, 2.1…
Here we report on the finding of pure boron nitride (BN) nanotubes that do not contain any additional inclusions and on a new method for their growth: laser heating of boron nitrides at high nitrogen pressure (5–15 GPa). The multiwalled nanotubes were observed using high resolution electron microscopy and were chemica…
This 1996 book summarises the state of knowledge on the microscopic behaviour of oxide surfaces. The first chapter of the book summarises classical approaches, introduces the concept of ionicity, and describes the mixed iono-covalent character of the oxygen cation bond in bulk materials. The next three chapters focus…
A new approach, plasma-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA), was used to introduce PEG graft chains with hydroxyl end groups onto a polyurethane (Tecoflex) surface. After argon plasma treatment and subsequent exposure to air, graft polymerization onto Tecoflex films was allowed to…
Microporous polypropylene fibers were prepared by stretching polypropylene fibers containing poly(methylsilsesquioxane) filler. The properties of the resultant fibers are controllable by adjusting the filler content and stretching degree. The resultant fibers have a fine texture of polypropylene fibrils, in which the…
Two liquid crystal forming polysaccharides, hydroxypropyl cellulose and chitosan, were blended in aqueous acetic acid solutions and were crosslinked with dialdehydes (glyoxal and glutaraldehyde) as crosslinker and hydrochloric acid as catalyzer. The crosslinkability, morphology, solubility, and tensile properties of t…
Three linear low density polyethylene (LLDPE) resins of similar melt index and density were synthesized with different comonomers in the Unipol pilot-plant scale reactor. The molecular structure, blown film morphology, and film strength properties of the resins have been comprehensively characterized. The film dart dr…
Nylon-nitrile rubber blends having different plastic-rubber component ratios (100/0, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, and 0/100) were prepared by melt mixing technique in a Rheocord-90 at a temperature set at 180°C. The mixing characteristics of the blends have been analyzed from the rheographs. The mo…
Ethylene-propylene copolymer (EP) was functionalized with glycidyl methacrylate (GMA) by means of a radical-initiated melt grafting reaction. FTIR and ESCA were used to characterize the formation of EP-g-GMA copolymers. The content of GMA in EP-g-GMA was determined by using hydrochloric acid/xylene titration. Effects…
Incompatible polymer blends between polyamide-6 (PA6) and poly(phenylene oxide) (PPO) have been compatibilized in situ by the styrene-glycidyl methacrylate (SG) reactive copolymers. The epoxy functional groups in SG copolymers can react with the PA6 amine and carboxylic endgroups at interface to form various SG-g-PA6…
Four types chitosan-based hydrogels have been prepared: cross-linked chitosan (cr-CS), cross-linked chitosan interpenetrating polyether polymer network (cr-CS/PE semi-IPN), cocross-linked chitosan and gelatin hybrid polymer network (CS/Gel HPN), and Chitosan/Pectin (CS/Ptn) ionic complex hydrogels. Water was used as a…
In this article we present overall crystallization characteristics of five polycaprolactone samples with mean molecular weights ranging from 50,000 to 400,000. The crystallization temperatures and heats of crystallization are determined as a function of mean molecular weight as well as for cooling rates in the range 0…
A new approach, plasma-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA), was used to introduce PEG graft chains with hydroxyl end groups onto a polyurethane (Tecoflex) surface. After argon plasma treatment and subsequent exposure to air, graft polymerization onto Tecoflex films was allowed to…
We develop a model to study the thermal expansion of surfaces, wherein phonon frequencies are obtained from ab initio total energy calculations. Anharmonic effects are treated exactly in the direction normal to the surface, and within a quasiharmonic approximation in the plane of the surface. We apply this model to th…
LEED experiments show that Li adsorbed at Cu(100) surfaces at room temperature induces a (2x1) missing row substrate reconstruction while adsorption at lower temperatures, T=180 K, results in an unreconstructed Cu(100)+c(2x2)--Li overlayer structure. Substrate reconstruction has not been observed for Na nor for K adso…
Competition between conductive cooling and advective heating occurs whenever hot fluid invades a cold environment. Here the solidification of hot viscous flow driven by a fixed pressure drop through an initially planar or cylindrical channel embedded in a cold rigid solid is analysed. At early times, or far from the c…