Materials Literature
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Violet/blue photoluminescence was observed from epitaxial cerium oxide films on silicon substrates. The films were deposited on silicon (111) substrates under ultrahigh vacuum conditions using pulsed laser ablation of a cerium oxide target and treated by rapid thermal annealing in argon. High resolution transmission e…
Gas transport properties of homo- and copolyimides prepared from 3,3′,4,4′- and 2,2′,3,3′-thiaphthalic dianhydride (p-TDPA and m-TDPA, respectively) with 4,4-oxydianiline (ODA) were investigated. The fractional free volume of m-TDPA-ODA is larger than that of p-TDPA-ODA, and the chain segmental mobility of the former…
This work deals with the effect of compatibilizer on the morphological, thermal, rheological, and mechanical properties of polypropylene/polycarbonate (PP/ PC) blends. The blends, containing between 0 to 30 vol % of polycarbonate and a compatibilizer, were prepared by means of a twin-screw extruder. The compatibilizer…
In conductive polymer compounds, the filler volume fraction at which a network of touching particles is formed is not a constant but depends on the manufacturing process. By applying three main features—particle-particle interaction, dynamics of agglomeration, and structure of agglomerates—which are well known in coll…
CeO2 nanometer powders of different sizes were prepared at low temperature by pyrolysis of amorphous citrate. XRD patterns show that CeO2 is cubic in structure, space group O-h(5)-F-M3M. TEM indicates that the prepared CeO2 is spherical in shape, and the particle size distribution is in narrow range. It was found that…
Copolymers of L-lactic acid (LLA) with DL-mandelic acid (DLMA), 4-hydroxybenzoic acid, 4-acetoxybenzoic acid, DL-malic acid, or anhydrous citric acid were synthesized via direct copolycondensation in the presence of 1,4-butanediol, using stannous octoate as catalyst. The effect of the comonomer and the comonomer ratio…
A variety of inorganic fillers are investigated to determine their impact on the response of filled polysiloxane elastomers to cyclic stress in hot air and in hot poly(dimethylsiloxane) PDMS fluid environments. Three fillers stabilize the polysiloxane networks to cyclic stress: zinc oxide, tin oxide, and copper oxide.…
The surface free energy and surface structure of poly(tetrafluoroethylene) (PTFE) film treated with low temperature plasma in O2, Ar, He, H2, NH3, and CH4 gases are studied. The contact angles of the samples were measured, and the critical surface tension γc (Zisman) and γc (max) were determined on the basis of the Zi…
The vibrational properties of amorphous SiO2 were studied within first-principles density functional theory. The calculated spectrum is in good agreement with neutron data, showing, in particular, a double peak in the high-frequency region. This doublet results from different local modes of the tetrahedral subunits an…
In conductive polymer compounds, the filler volume fraction at which a network of touching particles is formed is not a constant but depends on the manufacturing process. By applying three main features—particle-particle interaction, dynamics of agglomeration, and structure of agglomerates—which are well known in coll…
The electrical properties of individual bundles, or "ropes," of single-walled carbon nanotubes have been measured. Below about 10 kelvin, the low-bias conductance was suppressed for voltages less than a few millivolts. In addition, dramatic peaks were observed in the conductance as a function of a gate voltage that mo…
Low- and intermediate-level radioactive waste (L/ILW) contains substantial amounts of cellulosic materials. In Switzerland ~50% of the organic waste is cellulosic (<em>1</em>). In a cementitious L/ILW repository, the large amounts of cement produce alkaline environments in which the pH of the cement pore water remains…
Understanding the nature of chemical bonding between natural organic matter (NOM) and clays is an important step toward understanding the chemistry controlling the fate and bioavailability of organic contaminants in soils and sedi ments. Many organic contaminants preferentially associate with NOM, and adsorption of NO…
The lattice instabilities of perovskite structure oxides are responsible for many of their interesting properties, such as temperature-dependent ferroelectric phase transitions. First-principles calculations using linear response theory provide an accurate means to determine the lattice dynamics throughout the entire…
Physical mechanisms of intercalation of semiconductors are determined, establishing the main laws of intercalation, and the physical nature of new phenomena and effects induced by intercalation are explained; general statements for obtaining intercalates with characteristics assigned in advance are also developed.
A method for (111) oriented diamond film synthesis has been developed using controlled seeding of micron-sized diamond particles by electrophoresis. Different sizes of diamond powders (0.25 and 5μm) were electrophoretically seeded on silicon substrates using diamond suspensions in organic solvents (acetone, methanol,…
A low temperature process (350 °C&lt;T&lt;500 °C) for nanocrystalline diamond film growth by microwave plasma-enhanced chemical vapor deposition has been developed that yields high rates (up to 2.5 μm/h) at relatively low plasma powers (0.5 kW). In contrast to the widely used H2-rich mixtures of CH4 or CO and…
We study the dynamic properties of a fluid interface of nanometric curvature formed by capillary condensation between solid substrates. The interaction force between the substrates is measured with a surface force apparatus, and gives access to the line force acting on the three-phase contact line. We focus on a situa…
The step density model of reflection high-energy electron diffraction oscillations is investigated. Within this model, the temporal evolution of the specular beam intensity during growth by molecular beam epitaxy represents the evolution of the step density during deposition. This is found to be inconsistent with diff…
Starting from the basic constitutive equation that describes the magnetic viscosity of a ferromagnetic material, under the single assumption of a constant external field H, a connection is shown between the different expressions used to determine experimentally the fluctuation field . The simplest method uses the rela…