Ultrafast high-temperature sintering and thermoelectric properties of n-doped MgSi.

Ultrafast high-temperature sintering (UHS) is a recently proposed technique able to synthesize and sinter dense materials within seconds. Although UHS has already proved its effectivity with a large set of materials, spanning from refractory ceramics to complex metal alloys, any application to thermoelectric materials is today still lacking. MgSi is a well-established thermoelectric material.

New Sustainable Multilayered Membranes Based on ZrVTi for Hydrogen Purification.

Some metals belonging to groups IV and V show a high permeability to hydrogen and have been studied as possible alternatives to palladium in membranes for hydrogen purification/separation in order to increase their sustainability and decrease their costs. However, to date, very few alloys among those metals have been investigated, and no membrane studies based on 4-5 element alloys with low or zero Pd content and quasi-amorphous structure have been reported so far. In this work, new membranes based on ZrVTi- and ZrVTiPd alloys were tested for the first time for this application.

Optical Limiting of Carbon Nanohorn-Based Aqueous Nanofluids: A Systematic Study.

Nowadays, the use of lasers has become commonplace in everyday life, and laser protection has become an important field of scientific investigation, as well as a security issue. In this context, optical limiters are receiving increasing attention. This work focuses on the identification of the significant parameters affecting optical limiting properties of aqueous suspensions of pristine single-wall carbon nanohorns.

Surface oxidation of single wall carbon nanohorns for the production of surfactant free water-based colloids.

In this work, powders of Single Wall Carbon Nanohorns (SWCNHs), a typical hydrophobic material, were oxidized with concentrated HNO with the aim of surface carboxylation and consequent improved hydrophilicity and dispersibility in polar solvents. Dynamic Light Scattering and ζ-potential measurements demonstrated that very stable colloidal suspensions of SWCNH in water were obtained in total absence of stabilizers. By properly optimizing the reaction parameters, the suspensions achieved stability even higher than colloids with similar composition but prepared with the use of surfactants.

Tuning the thermal diffusivity of silver based nanofluids by controlling nanoparticle aggregation.

With the aim of preparing stable nanofluids for heat exchange applications and to study the effect of surfactant on the aggregation of nanoparticles and thermal diffusivity, stable silver colloids were synthesized in water by a green method, reducing AgNO₃ with fructose in the presence of poly-vinylpyrollidone (PVP) of various molecular weights. A silver nanopowder was precipitated from the colloids and re-dispersed at 4 vol% in deionized water. The Ag colloids were characterized by UV-visible spectroscopy, combined dynamic light scattering and ζ-potential measurements, and laser flash thermal diffusivity.

Experimental stability analysis of different water-based nanofluids.

In the recent years, great interest has been devoted to the unique properties of nanofluids. The dispersion process and the nanoparticle suspension stability have been found to be critical points in the development of these new fluids. For this reason, an experimental study on the stability of water-based dispersions containing different nanoparticles, i.

Absorption and scattering properties of carbon nanohorn-based nanofluids for direct sunlight absorbers.

In the present work, we investigated the scattering and spectrally resolved absorption properties of nanofluids consisting in aqueous and glycol suspensions of single-wall carbon nanohorns. The characteristics of these nanofluids were evaluated in view of their use as sunlight absorber fluids in a solar device. The observed nanoparticle-induced differences in optical properties appeared promising, leading to a considerably higher sunlight absorption with respect to the pure base fluids.

Growth of p- and n-dopable films from electrochemically generated C60 cations.

The formidable electron-acceptor properties of C60 contrast with its difficult oxidations. Only recently it has become possible to achieve reversibility of more than one electrochemical anodic process versus the six reversible cathodic reductions. Here we exploit the reactivity of electrochemical oxidations of pure C60 to grow a film of high thermal and mechanical stability on the anode.

Sims characterization of La0.7Sr0.3MnO3 films for solid oxide fuel cell applications.

Among solid oxides exploited to prepare efficient fuel cells, La(1-x)SrxMnO3 manganites have been widely studied and used as cathodes, because of their high conductivity at the working temperatures, good thermal stability and compatibility with other cell components. A fundamental goal in solid oxide fuel cells technology consists in lowering the normal operating temperatures, e.g.

Surface chemistry study of RuO2/IrO2/TiO2 mixed-oxide electrodes.

DSA metal oxide electrodes such as the RuO(2)/IrO(2)/TiO(2) mixed system are widely studied for their excellent electrocatalytic activity. In order to understand their catalytic properties, the comprehension of the surface chemistry involved during electrochemical treatments is crucial. With this aim, RuO(2)/IrO(2)/TiO(2) mixed-oxide electrodes having various noble metal contents were studied by means of secondary ion mass spectrometry (SIMS).

Secondary ion mass spectrometry and X-ray photoelectron spectroscopy investigation on chemical vapor deposited CeO(2-)ZrO(2)-TiO(2) thin films.

Mixed CeO(2)-ZrO(2) systems have attracted widespread interest for their use in three-way catalyst (TWC) technology for automotive exhaust conversion to non-toxic products. In this work, CeO(2)-ZrO(2) thin films were deposited, via chemical vapor deposition, in order to obtain nanoscale materials with a high surface-to-volume ratio, with precise control of system properties. The addition of TiO(2) as buffer layer was also investigated.