Materials Literature
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Erosion phenomenon of polyimide film under the hyperthermal atomic oxygen beam exposure, which is a simulated low Earth orbit space environment, has been investigated. The polyimide film was spin-coated on a sensor crystal of a quartz crystal microbalance, and the mass of the film was measured under the atomic oxygen…
Cermets composed of nickel metal and Y2O3-ZrO2-TiO2 ternary ceramics were investigated by X-ray diffraction, dilatometry, electrical and microstructural measurements and are regarded as improved anode materials with respect to long-term stability. With increasing titania content it was possible to minimise the electri…
The amorphous phase of hydrogenated carbon nitride, a -CN x :H (0 ≦ x ≦1), films may have clusters consisting of a mixture of sp 2 - and sp 3 -hybridized materials with cluster sizes of 0.2–2 nm. The hydrogen termination limits the size of the carbon and carbon nitride clusters. It also influences the mechanical prope…
Aromatic copolyimides were prepared using 2,3,3′,4′-biphenyltetracarboxylic dianhydride (asymmetric BPDA or a-BPDA) and several aromatic diamines with flexible ether linkages to obtain melt-processable polyimides (PIs) with balanced properties, i.e. high T g , high thermo-oxidative stability, low melt viscosity, and s…
The influence of impurities on the crystallization kinetics of NaCl was investigated in a fluidized bed crystallizer. The growth and dissolution rates were related to the supersaturation and impurity concentrations. The effect of different impurities on the growth rate of NaCl crystals can be divided into thermodynami…
Abstract A synthetic octahedral-site-vacancy-free annite sample and its progressive oxidation, induced by heating in air, were studied by powder X-ray diffraction (pXRD), Mössbauer spectroscopy, nuclear reaction analysis (NRA), Raman spectroscopy, X-ray fluorescence (XRF) spectroscopy, gas chromatography (GC), thermog…
The successful use of dipyrromethanecarbinols in rational routes to porphyrinic macrocycles requires catalysis conditions that enable irreversible condensation, thereby avoiding substituent scrambling and formation of undesired porphyrin products. Previously, successful conditions of trifluoroacetic acid (TFA) (30 mM)…
A model for the population dynamics of Er3+ in tellurite glasses with high erbium concentrations is proposed. Luminescence decay curves from transitions of 4I13/2→4I15/2 and 4S3/2→4I15/2 were measured experimentally. Upconversion coefficients were obtained by numerically solving the rate equations of the model to fit…
Monazite was continuously coated onto Nextel 720 fibers, using an aqueous precursor and in‐line heat treatment at 900°–1300°C. Some experiments were repeated with alumina‐doped precursors. Coated fibers were heat‐treated for 100 h at 1200°C. Coatings were characterized by optical microscopy, scanning electron microsco…
Washed and unwashed rhabdophane (LaPO 4 · x H 2 O) sols were used to apply monazite coatings to 3M Nextel 720 and 610 fibers. This precursor was designed to minimize stress corrosion from gaseous decomposition products at high temperature. The coatings were heat‐treated in‐line at 900°–1300°C, in air, using a continuo…
We have fabricated epitaxial thin films of the relaxor Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) and multilayer structures of relaxor/ferroelectric Pb(Mg 1/3 Nb 2/3 )O 3 /PbTiO 3 (PMN/PTO) using pulsed laser deposition. We present results obtained using reflection high energy electron diffraction (RHEED), x-ray diffraction (XRD) an…
This work deals with the factors affecting the reactivity of the CaO-SiO2-Al2O3-Fe2O3 mixture. Especially, the effect of the mixture's fineness and the effect of various additives are studied. Two groups of samples were studied. The first one consisted of limestone and clay mixtures having the same chemical compositio…
Bimetallic alloys have been considered in terms of their wetting behavior on semiconducting BaTiO3. In an earlier study, wetting behavior was strongly linked to ohmic contact behavior. However, the wetting behavior does not always correlate in the form of high work of adhesion-low contact resistance. The departure fro…
The anhydrous acid strontium oxalate Sr(HC 2 O 4 )⋅½(C 2 O 4 ) was obtained by thermal decomposition of the hydrated acid strontium oxalate Sr(HC 2 O 4 )⋅½(C 2 O 4 )⋅H 2 O. This non-hygroscopic compound crystallizes in the space group P 2 1 / c (No. 14) with unit cell parameters: a =0.796 61(7) nm, b =0.9205(1) nm, c…
The interaction of reduced transition-metal porphyrins [e.g. PMn (II), PFe (II), PCo (II)] with oxygen species (· O 2 ·, H 2 + O ·/ HO ·, HOO ·, · O ·) involves radical/radical coupling to form covalent bonds. Coordinately unsaturated iron(II) porphyrins form two sigma bonds with · O 2 ·(-Δ G BF = 1–6 kcal mol -1 ) vi…
Homogeneous mixtures of nanocrystalline powders of NiO-YSZ were obtained by combustion synthesis, and used to prepare cermet/YSZ/cermet symmetrical cells by co-pressing, co-firing at 1450 °C, and reduction in 10 % H2 – 90 % N2 at 800 °C. The resulting Ni/YSZ cermets are porous and adherent to the electrolyte, and its…
Abstract Flow‐induced coalescence in complex flow fields is studied using an in situ, real‐time small‐angle light scattering technique. Coalescence in a model polyisobutene–polydimethylsiloxane immiscible blend is triggered through step‐downs in the flow rate, creating a transition from a breakup‐controlled morphology…
The relaxed configurations of yttria-stabilised zirconia (YSZ) between 3 and 10 mol % of Y 2 O 3 were modeled using the pseudopotential technique. In the displacive limit of a double-well potential model, the vibrational mode corresponding to the soft phonon in pure c -ZrO 2 was calculated for each Y 2 O 3 composition…
Layered double hydroxides are antitype 2/1 clay minerals that can be synthesized rapidly under laboratory conditions. Due to their high anion exchange capacities, layered double hydroxides have been investigated as potential adsorbents for removal of anionic contaminants from aqueous systems. In this study, uncalcined…
A high temperature solid oxide fuel cell has been operated in low humidity (3 % H2O) methane using Y0.20Ti0.18Zr0.62O1.90 (YTZ) as the anode. The mechanism of methane electro-oxidation was investigated using ac and dc techniques at different anodic overpotentials and methane concentrations in the temperature range 788…