Preparation and characterization of siliceous material using liposomes as template
Material synthesis using unilamellar liposomes with a high sol-gel temperature transition phase as a template leads to a new silica material.
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Temperature induced changes on the structure and the dynamics of the “tetrahedral” glasses and melts of ZnCl2 and ZnBr2
Glassy, supercooled, and molten ZnCl2 and ZnBr2 have been studied by Raman spectroscopy over the broad temperature range −196 to 800 °C in an effort to follow in detail the structural changes caused by temperature variation. A systematic study has also been undertaken for the corresponding crystalline polymorphs showi…
Phase behavior and concentration fluctuations in suspensions of hard spheres and nearly ideal polymers
The phase behavior and concentration fluctuations in suspensions of hard sphere colloids and nonadsorbing polymers under nearly ideal solvent conditions is studied experimentally. A remarkably different qualitative behavior compared to the athermal solvent case is observed for the dependence on polymer/particle size a…
In situ transmission electron microscopy investigation of Ce(iv) and Pr(iv) reducibility in a Rh (1%)/Ce0.8Pr0.2O2–x catalyst
In-situ Atomic Resolution Transmission Electron Microscopy studies carried out on a Rh/Ce0.8Pr0.2O(2-x) catalyst, under hydrogen in the temperature range 298-1223 K, show the occurrence of consecutive reduction of Pr4+ and Ce4+ ions, and the formation of an oxygen-deficient Ln16O30 (Ln: Ce, Pr) ordered phase.
Effect of a nearby charge-ordered phase on correlation functions in ionic systems
The charge–charge and number–number correlation functions are investigated using a mean-field density functional for the restricted primitive model (hard-sphere and Coulomb interactions) supplemented with short-ranged attractive forces. The system exhibits phase separation into ion-dilute and ion-dense phases, and the…
Air shear driven flow of thin perfluoropolyether polymer films
We have studied the wind driven movement of thin perfluoropolyether (PFPE) polymer films on silicon wafers and CNx overcoats using the blow-off technique. The ease with which a liquid polymer film moves across a surface when sheared is described by a shear mobility χS, which can be interpreted both in terms of continu…
Radiation detection devices made from CVD diamond
CVD diamond is a remarkable material for the fabrication of radiation detectors. The radiation hardness, chemical resistance and high-temperature operational capabilities of diamond motivate its use in the fabrication of devices operating in hostile environments such as those encountered in the nuclear industry and hi…
Surface conductivity on hydrogen terminated diamond
Hydrogen terminated diamond exhibits surface conductivity of a p-type character. However, hydrogen termination itself is not sufficient to promote this effect and it has been shown by various authors that an aqueous layer containing adsorbates of a particular electronegativity is required to promote electron out diffu…
Composite cathode based on yttria stabilized bismuth oxide for low-temperature solid oxide fuel cells
Composites consisting of silver and yttria stabilized bismuth oxide (YSB) have been investigated as cathodes for low-temperature honeycomb solid oxide fuel cells with stabilized zirconia as electrolytes. At 600 °C, the interfacial polarization resistances of a porous YSB–Ag cathode is about 0.3 Ω cm2, more than one or…
Ion implantation of diamond for electronic applications
Ion implantation studies on diamond have been reported for over 30 years. Initial claims of achieving doping in this way, probably related primarily to electrical effects caused by intrinsic radiation damage. Since then, a better understanding of defect creation and accumulation during ion implantation has emerged. Th…
Electronic devices from diamond-like carbon
This paper reviews the work carried out over the past few years on the application of diamond-like carbon (DLC) materials to electronic devices. The use of such materials is still in its infancy due to their high defect state density and associated low mobilities. To date, the major effort in the electronic field has…
Intershell conductance in multiwall carbon nanotubes
A computational study of the electron transport properties of multiwall carbon nanotubes (MWNT's) is presented. The study is focused on the role of intershell interactions and the resistance associated with transport between neighboring shells. The tight-binding approximation is used to describe finite double-wall nan…
Magnetic properties and magnetic entropy change of LaFe11.5Si1.5Hyinterstitial compounds
LaFe11.5Si1.5Hy interstitial compounds have been prepared by hydrogen absorption and subsequent desorption. The Curie temperatures are easily tunable for a wide temperature range from ~ 195 to ~ 340 K by hydrogen content. The maximal magnetic entropy changes, under a magnetic field change of 0?5 T, are as large as 16.…
Dislocation-enhanced ionic conductivity of yttria-stabilized zirconia
The ionic conductivity of yttria-stabilized zirconia (YSZ) single crystals (10 mol %Y2O3–ZrO2) was enhanced by introducing high density of dislocations. YSZ single crystals were systematically deformed by compression tests at 1300 °C, and their electrical conductivity was measured by an AC impedance method. It was con…
Electronic and atomic structure of diamond-like carbon
The electronic structure of diamond-like carbon is reviewed. The sp 3 content varies linearly with density experimentally and in simulations. The bandgap is determined by the fraction and arrangement of sp 2 sites. Raman scattering can be used to probe the arrangement of sp 2 sites. The π states of sp 2 sites form two…
Thermal conductivity of elemental crystalline silicon clathrate Si136
The thermal conductivity and heat capacity of a guest-free polycrystalline silicon clathrate with the type-II hydrate crystal structure is reported. The magnitude of the thermal conductivity at room temperature is only slightly larger than that of vitreous silica, and is thirty times lower than that of diamond structu…
Growth condition dependence of morphology and electric properties of ZnO films on sapphire substrates prepared by molecular beam epitaxy
Zinc oxide (ZnO) films were grown on sapphire (112̄0) substrates by molecular beam epitaxy under oxygen radical irradiation. The effect of the growth conditions, including the Zn/O ratio supplied to the film surface, on the electrical properties of ZnO films was studied in relation to the film morphology. We found tha…
Neat macroscopic membranes of aligned carbon nanotubes
Thick macroscopic membranes of magnetically aligned single-wall carbon nanotubes (SWNT) have been produced via high pressure filtration of aqueous surfactant-suspended SWNT in a magnetic field, resulting in membrane thicknesses of 10 μm and surface areas of 125 cm2. Field strengths of 7 and 25 T were used. Polarized R…
A study on the effect of surface treatment of carbon nanotubes for liquid crystalline epoxide–carbon nanotube composites
Chemical surface oxidation of carbon nanotubes was employed to modify the interfaces between liquid crystalline epoxide (LCE) molecules and carbon nanotubes (CNs). Polar functional groups are formed on the surfaces of the carbon nanotubes as a result of the treatment. The thermotropic behavior of the nematic liquid cr…
Structure and phase diagram of high-density water: The role of interstitial molecules
The structural transformations occurring to water from the low- to the high-density regimes have been studied by classical molecular dynamics calculations. The local structure is analyzed through a proper choice of the relevant orientational distribution functions. This approach sheds light on the key role played by t…