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Purpose The study aimed to identify the environmental hotspots of lab-scale preparation of high purity porous Al2O3 pellets with suitable feature to work properly as metal layer-based deposition substrates for hydrogen separation membranes. The work intention was providing hints that may help the designing of upscaled systems, fundamental for the development of a possible future industrial production of hydrogen separation metal layer-based membranes technology. Methods The goal of this study was achieved assessing and analyzing environmental impacts of Al2O3 pellet production at lab scale. Primary data were collected in Padua laboratories of National Research Council of Italy. Secondary data were retrieved from Ecoinvent 3.7 database. Life cycle assessment (LCA) was performed using Environmental Footprint 3.0 method employing SimaPro 9.3 as software. Moreover, the CML LCIA method v. 4.7 was used to verify the robustness analysis of characterized results. Results Life cycle impact assessment highlighted as the main driver of environmental impacts was mainly associated to the pellet consolidation process and their morphological characterization stage. In particular, the impact of the first energy consuming process resulted strictly related to the peculiar energy mix used (linked to the laboratory geographical location). Conversely, morphological characterization stage was found to affect mainly the mineral resource depletion category due to the Au coating used for performing scanning electron microscope (SEM) analyses. Conclusions The study identified the environmental hotspots related to lab-scale preparation of porous alumina pellets as substrate for hydrogen separation metal layer-based membranes. The optimization strategies evaluated in this work were addressed to improve the environmental profile of experimental activities considering several scenarios, in view of a possible industrial scale-up.

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. Mg2Si is a well-established thermoelectric material. It is based on wide available non-critical raw materials, it is non-toxic, lightweight and it expresses its best thermoelectric performances in the intermediate temperature range (up to about 600 °C). Mg2Si is typically produced with powder processing by Spark Plasma Sintering (SPS), partially limiting its widespread diffusion also due to the costly production technique. Here we present a simple route to sinter Mg2Si pressed powders by UHS. The process allowed to obtain dense samples (with relative densities >95%) with 20 s heating up to about 1080 °C followed by a rapid free cooling, a total thermal history below 1 min, and with energy demand at the Wh scale. The high process rate proved its efficacy in preventing grain growth and in avoiding any significant Mg evaporation. A full thermoelectric functional characterization is presented for Mg2Si and Bi-doped Mg2Si, together with a comparison with SPS-produced properties.

A composite ferronematic system based on the nematic liquid crystal E7, doped with lath-like goethite magnetic nanoparticles of volume concentrations 10−3, 5 × 10−4, and 10−5, was investigated. Both surface acoustic waves (SAWs) and the magneto-optical effect were used to study the influence of magnetic nanoparticles on ferronematic liquid crystals’ structural changes, focused above all on structural transitions. The responses of SAW attenuation and light transmission to external magnetic fields were investigated experimentally under linearly increasing/decreasing or jumped (time influence) magnetic fields, respectively. An investigation of temperature on structural changes was performed, as well. The experimental results validated the decrease in the threshold field of the ferronematic composites in comparison with the pure E7, as well as an increase in the transition temperature with the increasing volume fraction of nanoparticles. The effect of the nanoparticles’ concentration on both total structural changes and residual attenuations at the vanishing magnetic field was also registered. The light transmission measurements confirmed the effect of the concentration of goethite nanoparticles on the resultant magneto-optical behavior, concerning both its stability and switching time.

Phase change material emulsions (PCMEs) were largely investigated as potential working fluids for various applications as in HVAC systems, solar thermal storage, and heat transfer. They basically contain water and phase change materials, possess much larger energy storage capacity than currently used chilled water based systems and exploit higher thermal conductivity than bulk PCM reservoirs. Main barriers to their application are the difficulty in maintaining emulsion stability and the undercooling effect. In this work, a new solvent-assisted route was developed to produce nano-emulsions of commercial paraffin waxes in water. Concentrations from 2 to 10 wt% were obtained starting from two commercial paraffin waxes, with nominal melting temperatures around 55 °C and 70 °C. The droplet dimensions were verified and resulted below 100 nm for lower concentrations and around 180–220 nm for 10 wt%. The stability of emulsions was verified by long-term tests. An undercooling effect was verified and strongly reduced by testing some nucleating agents (a paraffin melting at 70 °C in the paraffin melting at 55 °C or a carbon nanostructure, single wall carbon nanohorns). The heat of melting was lower than expected, probably due to PCM molecules on the surface of the nanoparticles anchored to the surfactant. However, calculating the thermal capacity of PCMEs with respect to pure water, a gain up to 40% for operating temperatures close to PCM melting temperature was estimated. Optical properties of single wall carbon nanohorns/paraffin composites were also measured.

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. The unprecedented deposition of micrometric-based multilayers was performed via high-power impulse magnetron sputtering onto porous alumina substrates. Dense Pd/ZrxVyTizPdw/Pd multilayers were obtained. The composition of the alloys, morphology and structure, hydrogen permeance, selectivity, and resistance to embrittlement were tested and analyzed depending on the deposition conditions, and the membrane with the enhanced performance was tuned. The environmental impact of these membranes was also investigated to ascertain the sustainability of these alloys relative to more common Pd77Ag23 and V93Pd7 thin-film membranes using a life cycle assessment analysis. The results showed that the partial substitution of Pd can efficiently lead to a decrease in the environmental impacts of the membranes.

This work analyzes the dynamic viscosity, surface tension and wetting behavior of phase change material nano–emulsions (PCMEs) formulated at dispersed phase concentrations of 2, 4 and 10 wt.%. Paraffin–in–water samples were produced using a solvent–assisted route, starting from RT21HC technical grade paraffin with a nominal melting point at ~293–294 K. In order to evaluate the possible effect of paraffinic nucleating agents on those three properties, a nano–emulsion with 3.6% of RT21HC and 0.4% of RT55 (a paraffin wax with melting temperature at ~328 K) was also investigated. Dynamic viscosity strongly rose with increasing dispersed phase concentration, showing a maximum increase of 151% for the sample containing 10 wt.% of paraffin at 278 K. For that same nano–emulsion, a melting temperature of ~292.4 K and a recrystallization temperature of ~283.7 K (which agree with previous calorimetric results of that emulsion) were determined from rheological temperature sweeps. Nano–emulsions exhibited surface tensions considerably lower than those of water. Nevertheless, at some concentrations and temperatures, PCME values are slightly higher than surface tensions obtained for the corresponding water+SDS mixtures used to produce the nano–emulsions. This may be attributed to the fact that a portion of the surfactant is taking part of the interface between dispersed and continuous phase. Finally, although RT21HC–emulsions exhibited contact angles considerably inferior than those of distilled water, PCME sessile droplets did not rapidly spread as it happened for water+SDS with similar surfactant contents or for bulk–RT21HC.

In this work, powders of Single Wall Carbon Nanohorns (SWCNHs), a typical hydrophobic material, were oxidized with concentrated HNO3 with the aim of surface carboxylation and consequent improved hydrophilicity and dispersibility in polar solvents. Dynamic Light Scattering and zeta-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. Surface damage and oxidation degree of SWCNHs were evaluated by SEM microscopy, Thermogravimetric Analysis, Residual Gas Analysis, XPS and UV-visible spectroscopy.

Lithium wall conditioning has improved the performance of many magnetic fusion devices. Li conditioning in the RFX-mod device was performed by: (1) a single Li pellet injector and (2) a multi-Li pellet injector during He plasma discharges; (3) a Li evaporator after He glow discharge cleaning and He plasma discharge exposure. This report compares the spatial and depth distributions of Li deposited on polycrystalline graphite witness samples at different locations in RFX-mod and the elemental and chemical compositions of the resulting surfaces. The sample surfaces were analyzed ex situ using secondary ion mass spectrometry (SIMS) and high-resolution X-ray photoelectron spectroscopy (HR-XPS). The results showed that Li pellet injection provided a relatively uniform toroidal coverage while Li evaporation produced highly localized Li deposition. A Li 1s HR-XPS peak at 56.5 eV binding energy (BE) characteristic of lithium-intercalated graphite was only observed with the sample exposed to Li evaporation. All of the samples exhibited a HR-XPS C 1s peak at 285.1–285.2 eV BE that is largely attributed to hydrogenated graphite. This finding suggests that hydrogenation of fresh graphite occurs during He plasma discharge exposures. Our results have implications for density control and the selection of Li conditioning techniques in magnetic fusion devices.

Goethite (α-FeOOH) nanorods have been synthesized using two different methods, by aging at different temperatures of ferrihydrite suspensions obtained through co-precipitation, or by fast conversion of ferrihydrite through ultrasonic irradiation. The synthesis method and parameters influenced the size and shape of nanoparticles. Stable colloidal suspensions of nanorods have been prepared by purification of the precipitates and subsequent dispersion in deionised water by sonication. The synthesized nanopowders have been characterized by Powder X-ray Diffraction and Scanning Electron Microscopy and the colloidal suspensions by Dynamic Light Scattering and ζ-potential measurements. The magnetic field at nuclei level has been investigated by Mossbauer spectroscopy. Moreover, since a colloidal suspension of goethite is a mineral liquid crystal and due to its peculiar magnetic properties, polarized radiation transmittance of colloids in the UV-vis-NIR range has been determined under different magnetic field directions and intensities. It has been found that the transmittance in the NIR range can be tuned by changing magnetic field direction and strength.

The goal of the study was to identify the environmental hotspots of an experimental research work at lab scale consisting in the physical vapor deposition magnetron sputtering of aluminum titanium nitride based thin coatings onto commercial laminated steel. The findings can provide useful insights for supporting the design of future experimental research campaigns, or instrumentation set-ups, with lower environmental impacts. Results highlighted that the main driver of impacts in the analyzed laboratory activities was the electricity used for instruments operations, in particular for the vacuum keeping. Thus, several optimization strategies were evaluated to reduce the overall electricity consumption, and to improve the environmental profile of experimental activities.

Enhancing the tribological performance of lubricants with nanoparticle additives is a recent challenge. The purpose of this study was to investigate the potential advantage of nanolubricants, a new class of advanced lubricants integrating nano-sized materials, to reduce friction and wear processes, in view of applications in compressors for refrigeration. An investigation of tribological and thermal properties of nanolubricants for vane-on-roller systems was carried out through ball-on-disk wear tests and thermal diffusivity photo-acoustic measurements from room temperature to 70 °C. Nanofluids containing different concentrations of graphene based nanostructures in oil were tested. Poly-alkylene glycol was selected as the oil, being a lubricant suitable for compressors operating with CO2 refrigerants. The suspensions resulted stable with time. The dispersed nanostructures played an important role in protecting surfaces against wear phenomena and in improving the friction properties and load carrying capability of raw oil. A maximum decrease of 18% for friction coefficient and over 70% for worn volume were estimated in boundary lubrication conditions, the most severe for tribological couplings. Finally, durability experiments and Stribeck tests confirmed the benefits produced by nano-additives in different lubrication regimes. Thermal investigation proved also the advantage of using nanolubricants in heat exchange properties in laminar flow conditions, e.g. during compressor power-up phases.

Galvanic displacement reactions between sacrificial oxide layers and metal cations, leading to the formation of secondary oxide layers, have been studied with the aim of collecting new experimental evidence on their mechanism. The study has been carried out by combining electrochemical methods, SEM-EDS and XPS depth profiling. Both porous and compact PbO2 layers have been used as sacrificial oxides and reacted, in different experiments, with: (i) a single low-valent cation, (ii) two cations in sequential exchange reactions or (iii) two cations simultaneously. The experimental results converged to show (i) a lack of correlation between the reaction driving force and the secondary oxide growth rate, (ii) the incorporation of cations from solution at the secondary oxide/electrolyte interface, (iii) the transport of Pb species through the growing secondary oxide layer and (iv) a major effect of mass transport on the growth rate.

The addition of nanoparticles in lubricating oils recently demonstrated to reduce the coefficient of friction and to increase the load-carrying capability of lubricant in coupled surfaces. In this work, different kinds of nanoparticles were tested as additives to engine oil to improve lubrication: copper and titanium oxide nanoparticles and single walled carbon nanohorns (SWCNHs). Two nanoparticle sizes were also tested in case of copper. The tribological properties of these nanofluids were evaluated by Stribeck tests, in order to compare the effect of nanoparticles on friction coefficient and electric contact resistance in different lubrication regimes. Stribeck curves showed that the coefficient of friction was reduced, compared to raw oil, by the action of Cu nanoparticles having 130 nm diameter, leading to a mean decrease of about 17%, and by SWCNHs, with a mean decrease of about 12%. Conversely, no significant changes were detected in presence of Cu nanoparticles having 50 nm diameter or of TiO2. The suspension viscosity and stability were also tested. Wear tests were also carried out, showing a reduction of wear rate up to nearly 50% for Cu nanoparticles (150 nm diameter) and around 30% for SWCNHs. The measurements showed that nanoparticles having size comparable to the mean roughness of coupled surfaces significantly improved the tribological properties of bare oil. An explanation of nanoparticle action is proposed.

BaCe0.65Zr0.2Y0.15O3-δ (BCZY) have been recently proposed for IT-SOFCs due to its high proton conductivity. On the other hand considerable efforts are directed towards the development of metal-supported cells. The combination of the potential advantages offered by either proton conductors based cells and metal supported configuration has never been explored. In this work the technological issues to produce proton conducting BCZY-Ni anodes stainless steel-supported were carefully investigated. A tailored porous metal support was produced by tape casting. Afterwards the anode was deposited by screen printing and the resulting bilayer sintered in reducing atmosphere. Each step of the production process was thoroughly investigated. A cations interdiffusion between the metallic support and the anodic layer was observed in all range of temperatures considered. The influence of a CeO2 barrier layer and anode thickness on the cations diffusion and a successful production of planar crack-free anode was deeply analyzed.

The work illustrates the preparation of stable suspensions of single-walled carbon nano-horns (SWCNHs) in engine oil and shows their tribological behavior at different temperatures. The suspension stability was verified by dynamic light scattering, and the viscosity of suspensions was measured. Stribeck test was used to evaluate the tribological performances of nano-lubricants in the 25-80 °C temperature range. The coefficient of friction was reduced with the addition of SWCNHs at all temperatures and concentrations. In particular, at T = 25 °C, the coefficient friction was reduced up to about 12 % in boundary regime even with a very low SWCNH concentration (0.01 vol%). Wear tests were carried out to verify results obtained from Stribeck characterization. A decrease in mean wear rate was observed at each temperature, between 25 and 30 %. In particular, at 25 °C, a decrease of about 30 % in wear rate was estimated. Friction coefficient decrease was also observed during all wear tests, probably due to the ball-bearing effect played by SWCNHs spherical aggregates. Therefore, SWCNHs revealed the potential to be promising candidates as additives, to develop a new class of lubricants that are suitable and effective in different operating environments. © 2014 Springer Science+Business Media New York.

The dependence of polarized optical properties of colloidal suspensions of goethite (α-FeOOH) nanorods in water and PAO base fluids under the action of an applied magnetic field are investigated in the ultraviolet, visible and near infrared from 300 to 1500 nm wavelength. We found that the transmittance in the NIR range can be tuned by changing magnetic field direction and strength. Moreover, we found that the magnetic field dependence of optical properties is strongly connected to the base fluid where magnetic nanoparticles are suspended. The obtained results show that the optical properties of goethite-based suspensions are very sensitive to even weak external magnetic fields, with promising perspectives for sensing applications.

In this study, new phase change material nanoemulsions (PCMEs) were designed and characterized as possible storage and heat transfer media for low-temperature thermal uses. Water- and (ethylene glycol + water)-based emulsions with fine droplets of n-heptadecane and RT21HC commercial paraffin were produced by a solvent-assisted emulsification method. No phase separation or significant growth in PCM drops were observed for the prepared emulsions through storage, after freeze–thaw cycles and under mechanical shear. Phase change transitions were characterized and a significant sub-cooling was observed, with solidification temperatures up to 13 K below the melting point. One pure alkane and two commercial paraffin waxes with higher melting points were considered as nucleating agents to reduce sub-cooling effect. Although the emulsions exhibited diminutions in thermal conductivity up to 9% with respect to the carrier fluids used as base fluid, enhancements in energy storage capacity (considering an operational temperature interval equal to the sub-cooling) reached 26% in the case of RT21HC nanoemulsion based on the (ethylene glycol + water) mixture that contained 10% in mass of paraffin. In addition, the thermal reliability of the nanoemulsions was verified analyzing the changes in latent heat after storage and throughout 1000 thermal cycles.

Cu nanoparticles (NPs) are widely studied to understand how they work in lubricant oils to improve its tribological properties. This paper describes the synthesis and characterization of Cu NPs of different size (φ = 60 and 130 nm) carried out in EG and the dispersion procedure used to prepare nanolubricants containing different amounts of NPs (0.005 vol% -0.01 vol% -0.02 vol%). The base oil was a commercially available lubricant oil for internal combustion engines. In order to study the influence of different parameters such as particles size and concentration on tribological properties of nanolubricants, the Stribeck curves were recorded at 25°C in the three lubrication regions (elasto-hydrodynamic, mixed lubrication, and boundary lubrication) and the results discussed. It was found that Cu NPs with a 130-nm mean diameter were more effective in reducing the coefficient of friction in all the lubrication regimes with respect to smaller ones.

This paper describes the cathodic electrodeposition of nickel hydroxides from NiCl2 at constant potentials. In a single-compartment electrochemical cell, the procedure yields black films that have the appearance of glassy carbon. XPS analyses reveal that the films consist of a mixture of Ni(OH)2 and NiOOH in a proportion that depends on the deposition potential; furthermore, SIMS analyses indicate that the coatings are richer in NiOOH in the inner regions towards the support. The electrochemical behavior has been compared with data obtained on electrodes based on pure Ni(OH)2 prepared by cathodic electrodeposition from Ni(NO3)2, following literature procedures. This comparison confirms the composite nature of black nickel hydroxide (BN) coatings, adding that Ni(OH)2 and NiOOH are present in nearly equal amounts. The electrocatalytic activity of BN electrodes was tested in the oxidation of methanol in alkaline solutions. Experimental results are consistent with a mechanism previously proposed in literature for the oxidation of organic compounds on nickel electrodes. Comparison with electrodes based on pure Ni(OH)2 shows that, in the low potentials region, the presence of a high amount of NiOOH causes a decrease of activity, while an opposite effect is observed when the potential is increased. The black nickel electrodes show a remarkable stability in repeated cycles of oxidation of methanol and O2 evolution; under similar conditions, conventional Ni(OH)2 films show an appreciable decrease in thickness, as evidenced by the decrease of peak charge in cyclic voltammetry experiments.

The higher manganese silicides (HMS), represented by MnSix (x = 1.71 to 1.75), are promising p-type leg candidates for thermoelectric energy harvesting systems in the middle-high temperature range. They are very attractive as they could replace lead-based compounds due to their nontoxicity, low-cost starting materials, and high thermal and chemical stability. Dense pellets were obtained through direct reaction between Mn and Si powders during the spark plasma sintering process. The tetragonal HMS and cubic MnSi phase amounts and the functional properties of the material such as the Seebeck coefficient and electrical and thermal conductivity were evaluated as a function of the SPS processing conditions. The morphology, composition, and crystal structure of the samples were characterized by scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction analyses, respectively. Differential scanning calorimetry and thermogravimetric analysis were performed to evaluate the thermal stability of the final sintered material. A ZT value of 0.34 was obtained at 600°C for the sample sintered at 900°C and 90 MPa with 5 min holding time.

Magnesium silicide (Mg2Si)-based alloys are promising candidates for thermoelectric (TE) energy conversion for the middle to high range of temperature. These materials are very attractive for TE research because of the abundance of their constituent elements in the Earth’s crust. Mg2Si could replace lead-based TE materials, due to its low cost, nontoxicity, and low density. In this work, the role of aluminum doping (Mg2Si:Al = 1:x for x = 0.005, 0.01, 0.02, and 0.04 molar ratio) in dense Mg2Si materials was investigated. The synthesis process was performed by planetary milling under inert atmosphere starting from commercial Mg2Si pieces and Al powder. After ball milling, the samples were sintered by means of spark plasma sintering to density >95%. The morphology, composition, and crystal structure of the samples were characterized by field-emission scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction analyses. Moreover, Seebeck coefficient analyses, as well as electrical and thermal conductivity measurements were performed for all samples up to 600°C. The resultant estimated ZT values are comparable to those reported in the literature for these materials. In particular, the maximum ZT achieved was 0.50 for the x = 0.01 Al-doped sample at 600°C.

A high temperature test rig to simultaneously measure electrical conductivity and thermopower is described. The apparatus allows to perform measurements in controlled atmosphere or vacuum to protect oxygen sensitive materials. A spring load mounting placed in a cold zone permits to reduce the thermal contact resistance between the sample and two metallic blocks (the hot side and the heat sink) even at high temperature. The hot side metal block is periodically heated to obtain the thermopower from the slope of the ?V vs ?T line. Conductivity is measured before each thermopower measurement by a linear four-wire method. The automatic data acquisition and analysis is controlled by a LabView-based interface. Two interchangeable setups are possible. The first one uses silver blocks and K-type thermocouples and is suitable for temperatures from 300 to about 1100 K. The second one uses W blocks and S-type thermocouples to allow higher temperatures measurements since all the hot zone parts are made of Al2O3, Pt or W. The device was tested using PdAg alloy and Ni rods and, for the low temperatures range, the NIST Standard Reference Material 3451 (bismuth telluride), strictly confirming the reference data.

Modified Reversed-Field eXperiment is an experiment of magnetic confinement of thermonuclear plasma in the Reversed-Field Pinch configuration. The toroidal device is designed to operate with hydrogen plasmas, and the most internal wall is entirely covered with polycrystalline graphite tiles. The disadvantage of graphite walls is the progressive hydrogen accumulation in graphite during operation. To overcome this problem, some graphite conditioning procedures are necessary (e.g. boronization, lithization and glow discharge). The critical role of graphite walls on plasma control suggested the use of secondary ion mass spectrometry (SIMS) technique for the evaluation of conditioning procedures efficacy. SIMS analyses of graphite samples after their exposure to plasmas or wall conditioning treatments are presented in this work. The SIMS technique resulted fundamental on the investigation of the boron distribution in the graphite tiles, and sample comparisons indicated the need for glow discharge cleaning system upgrading to improve the conditioning process and boronization uniformity. Copyright © 2012 John Wiley & Sons, Ltd.

A method for large-scale production of Single Wall Carbon Nanohorns (SWCNH) in a prototype reactor was tested with optimal thermodynamic conditions that favour high quality material formation at rates of about 100 g/h. The first productions demonstrated the excellent capability and flexibility of the approach. The plant typology that can be easily scaled up to tens the present scale, making possible to propose materials based on SWCNHs for real uses such as in hydrogen storage. In this framework, pristine and oxidized materials were characterized and tested.

In the RFX-mod Reversed Field Pinch experiment the wall is entirely covered by graphite tiles. The disadvantage of a graphite wall is that, except after wall conditioning procedures, such as boronization, lithization or glow discharge cleaning, the graphite becomes saturated with trapped Hydrogen, causing that during the discharge the particle recycling factor is approximately one and plasma density is entirely sustained by particle fluxes coming from the wall. In the paper the results of the analyses of graphite samples after their exposure to plasmas or wall conditioning treatments are presented. The topics addressed are: the deposition of Boron during different boronization treatments; the erosion and re-deposition of the Boron layer by Hydrogen plasmas; some remarks about the presence of Lithium in the wall since the beginning of lithization treatments.

In this work, BaCe0.65Zr0.20Y0.15O3−δ powders with a perovskite-type structure were successfully synthesized by a microwave-assisted sol–gel Pechini method (SGP). By comparison, powders having the same nominal stoichiometry were also prepared without the microwave assistance. For the syntheses, nitrates were used as metal precursors, and ethylenediaminetetraacetic acid and ethylene glycol were used as complexing and polymerizing agents, respectively. An extensive structural and morphological investigation by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) has been performed. Moreover, in order to check the phase transitions, simultaneous thermogravimetric and differential thermal analyses were (TG-DTA) performed on gels. With respect to the conventional Pechini method, the microwave-assisted process guaranteed a faster, energy-saving procedure for obtaining single-phase nanopowders of high purity. Moreover, a significant increase in pellet densities was achieved owing to a higher grain coalescence.

The La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM) catalyst and the novel Ru/La0.75Sr0.25Cr0.5Mn0.5O3-δ composite were investigated as alternative anodes for the direct utilization of propane in anode-supported solid oxide fuel cells. In particular, their synthesis and performance in direct propane reforming were studied. The LSCM powders were prepared by a sol–gel method based on a modified Pechini procedure. Single-phase LSCM perovskite powders were obtained. SEM micrographs of the LSCM powders revealed particles in the 200–300 nm range with a homogeneous grain distribution. The deposition of 5 wt.% metallic ruthenium nanoparticles on the LSCM perovskite powders was carried out by a microwave-assisted procedure. TEM investigations of Ru/LSCM composites showed a homogeneous distribution of metallic ruthenium nanoparticles with a mean grain size of around 2–3 nm. The catalytic activity of these potential anode materials was investigated for the following propane reforming processes: steam reforming (SR), autothermal reforming (ATR) and partial oxidation (POX) at 600, 700 and 800 °C. Very high propane conversion rates were observed under POX and ATR conditions at 700 and 800 °C for both the LSCM and Ru/LSCM compounds (> 92 at 700 °C and > 98% at 800 °C), whereas in the steam reforming environment, a satisfactory conversion was achieved only at 800 °C. The ruthenium presence was found to strongly improve the selectivity for H2 and syngas production for all of the experiments performed, reaching an approximately 90% syngas yield. Finally, good chemical stability after the catalytic tests was demonstrated for the LSCM and Ru/LSCM anode materials.

A systematic investigation on doped barium cerate perovskites on conductivity was performed by means of ac electrochemical impedance spectroscopy technique. BaCe0.85−xZrxY0.15O3−δ powders (x = 0, 0.1, 0.2, 0.3, 0.4) were prepared by a modified sol-gel Pechini method and sintered at 1,250 °C–1,450 °C, depending on Zr content, to obtain good densities (93–97% of the theoretical ones). The measured total conductivities for these solid solutions in three different atmospheres were reported: in dry oxygen, in dry nitrogen and wet (0.5 bar H2O) hydrogen (5%H2/Ar) atmospheres. Arrhenius plots recorded in dry oxygen as well as in dry nitrogen showed some residual hydration which remained in the specimens upon initial heating. The compositions with x = 0.3 and 0.4 gave conductivities close to 10−2 S/cm in 5%H2/Ar/H2O atmosphere at 600 °C. The isothermal conductivities values showed a little variation for x from 0.2 to 0.4 between 500 and 800 °C.

In this paper the role of the preparation route on the transport properties of the BaCe 1− x Y x O 3− δ solid solution with x = 0, 0.1, 0.15, and 0.2 has been studied. In particular, the samples were synthesized by means of the solid-state reaction and by a modified Pechini method. The effect of grain size on the sintering behaviour of the two samples batches was investigated by means of impedance spectroscopy and electron microscopy. It was found that a good sintering of the pellets can be achieved at 1250 °C for the samples prepared through the Pechini method. The ceramic route, even at higher temperatures, does not lead to good density values. The extensive conductivity measurements as a function of doping and gas environment (pure oxygen and argon + 10% H 2 + water) we carried out showed that the optimal Y-doping is around 15% and that a significant proton conductivity can be achieved for T lower than 500 °C. Above this temperature, the role of oxygen defects starts becoming relevant. Finally, the presence of a slope change in all the Arrhenius plots, irrespective to the gas environment, at about 450–500 °C was observed and qualitatively interpreted as due to a change in the nature of the main charge carriers involved.

Solid oxide fuel cell technology offers substantial advantages for clean and efficient power generation. However, the high working temperatures impose severe restrictions on the materials selection. The key to prolong the stack lifetime, widen the selection of materials and reduce the costs lies in lowering the working temperature. Two main approaches have been applied for this purpose: testing materials based on Gd doped CeO2, having higher ionic conductivity at lower temperatures, and decreasing the electrolyte thickness. At present, different methods have been studied for the deposition of fully dense thin coatings. Among them, the radio frequency magnetron sputtering technique is a powerful and versatile tool to deposit mixed oxide thin films in a wide thickness range (100 nm÷10 μm). In this report, the results about the deposition by RF magnetron sputtering of 1÷5 μm GDC films on anodic substrates will be presented.

The current work aims to describe surface weathering of ancient glasses in marine environment. All data are collected using different techniques: optical microscopy, RGA, surface techniques (XPS, SEM and SIMS). Three types of glass weathering have been observed: white glass, glossy glass and glass showing growth rings. A compact structure characterizes white glasses, while a porous structure with flaked layers is typical of glossy glasses. White glasses show different abundance of characteristic elements or molecules (Mg(II), Sb(V), Ti(IV) and micro-crystalline silica). Glossy glasses, instead, are characterized by peeling layers of nearly pure silica glass, with small differences in composition owing to ionic mobility phenomena. Data suggest a time relation between white and glossy glasses. Visible growth rings characterize the third class of glass. They are made of titanium and antimony compounds centers surrounded by many rings with the same composition. Their temporal evolution has been explained according to the theory of ‘Liesegang rings’. Hypotheses on antimony and titanium origins are reported.

Thin film layers of silica with calcium or magnesium ions were prepared by the sol–gel method in order to obtain protective coatings with low water affinity for historical glasses. The films were synthesised by pre-polymerised solutions of tetraethoxysilane [Si(OC 2 H 5 ) 4 ] (TEOS) and deposited by dipping soda-lime glasses. Then they were immersed in saturated solutions of Ca(OH) 2 or Mg(OH) 2 for time intervals of 1, 24 and 36 h to adsorb calcium or magnesium ions. No heat treatment was done, to apply this method to cover real historical glasses, which could be irreversibly damaged by high temperature. The X-ray photoelectron spectroscopy and secondary ions mass spectrometry analyses show that the films present an almost homogeneous in depth distribution of calcium or magnesium. Magnesium adsorbed films also present a decrease of free non-bridging oxygen (SiOH groups). By atomic force microscopy it was observed that the average roughness is low (around 10 A). Contact angle measurements reveal a degree increase starting from soda-lime uncoated glasses, through silica coated glasses up to calcium or magnesium adsorbed silica coated glasses. The data obtained revealed a real decrease of water affinity, strictly important to improve the protective performances of the films.

Modifications of nanocrystalline RuO2 and Ru films, chemical-vapor deposited on Ti substrates, are studied in aqueous media, at the initial stages of electrocatalytic O2 evolution. The microstructure, composition and morphology of the films are examined ex situ by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and atomic force microscopy (AFM). Results concerning the influence of electrochemical processing on the chemico-physical properties and electrode behavior are presented and discussed.

Single walled carbon nanohorns (SWCNHs) are a black nanoscale spherical aggregate of cylindrical tubes of graphitic carbon which differ from nanotubes in their "horn-like" shape. Their peculiar structure makes them one of the best electronconductors at a nanoscale level. Although not commercially exploited, their rapid environmental diffusion is expected to rise significantly in the next few years. Therefore, we appraised the ecotoxicology of SWCNH powders by taking into account the ecological role of the two species that were deployed in exposure experiments: polychaetes, Hediste diversicolor, and mussels, Mytilus galloprovincialis. Adult mussels and polychaetes were exposed to three SWCNH concentrations: 1, 5, and 10 mg L-1 and acute effects were measured after 24 and 48 h. Sub-lethal effects were estimated at level of physiological functions such as digestion in mussels (i.e. variations in lysosomal parameters and lipofuscin content) and the antioxidant system in both species (i.e. glutathione peroxidase activity and malondialdehyde content). SWCNH suspension in sea water was also characterised, highlighting the formation of aggregates the size of which was related to SWCNH concentrations and their resident time in the medium. The results showed that SWCNH affected the oxidative and lysosomal systems on the hepatopancreas and led to lysosomal alterations on haemocytes in mussels. The biological responses were less clear in polychaetes. This preliminary investigation highlighted the need of focusing future research efforts on possible physiological impairments caused by long-term exposure to SWCNHs in marine species. (C) 2013 Elsevier B.V. All rights reserved.

An investigation of cobalt oxide based nanocrystalline thin films by secondary ion mass spectrometry (SIMS) is presented. The coatings, whose composition ranged between CoO and Co3O4, were synthesized by chemical vapor deposition (CVD) on indium tin oxide (ITO) substrates, using cobalt(II) β-diketonate as precursor. The SIMS analysis revealed a satisfactory precursor conversion into the oxides and allowed distinction of regions in the films at different compositions. Film-substrate intermixing phenomena were evidenced and studied as a function of deposition temperature, film thickness and composition. Copyright © 2001 John Wiley & Sons, Ltd.

The influence of different RuO(2) crystallite sizes was investigated by secondary ion mass spectrometry (SIMS) on the oxide deposited on various support materials (Ni, Ti, Al(2)O(3), oxidized Si(100)). In order to examine the effect of an oxidic environment on the film structure, RuO(2) 20%-TiO(2) 80% at. mixed oxide was deposited on Ti. The polycrystalline coatings were prepared by heating the Ru (and Ti)-containing solution dropped on the supports.1 RuO(2) nanocrystalline coatings were grown by chemical vapor deposition (CVD) from Ru(COD)(eta(3)-allyl)(2).2 The identification of mixed oxide clusters showed the higher reactivity of Ni and Al(2)O(3) over the other substrates. Diffusion and migration characteristics were observed to be influenced by the nature of the support. The results are complementary to those of a previous SIMS investigation.3 Copyright 2000 John Wiley & Sons, Ltd.

The IrO(2)/RuO(2)/TiO(2) ternary system is well known for its electrocatalytic activity towards oxygen- and chlorine-evolution reactions. Electrochemical processing induces noticeable chemical and morphological modifications on these electrodes, depending on the noble metal oxide content. In this work, cathodic/anodic polarization and the oxygen-evolution reaction were studied in order to evaluate the electrocatalytic activity at various noble metal oxide percentages. The best performing electrode (30 mol% noble metal oxides) was analyzed before and after electrochemical tests by means of secondary ion mass spectrometry (SIMS) in order to determine the chemical composition modification which occurred on the surface and in deeper regions of the mixed-oxide film.

The Mg2Si-based alloys are promising candidates for thermoelectric energy conversion in the middle-high temperature range in order to replace lead compounds. The main advantages of silicide-based thermoelectrics are the nontoxicity and the abundance of their constituent elements in the earth crust. The drawback of such kind of materials is their oxygen sensitivity at high temperature that entails their use under vacuum or inert atmosphere. In order to limit the corrosion phenomena, nanostructured multilayered molybdenum silicide-based materials were deposited via RF magnetron sputtering onto stainless steel, alumina and silicon (100) to set up the deposition process and then onto Mg2Si pellets. XRD, EDS, FE-SEM and electrical measurements at high temperature were carried out in order to obtain, respectively, the structural, compositional, morphological and electrical characterization of the deposited coatings. At the end, the mechanical behavior of the system thin film/Mg2Si-substrate as a function of temperature and the barrier properties for oxygen protection after thermal treatment in air at high temperature were qualitatively evaluated by FE-SEM.

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. Scattered light was found to be not more than about 5% with respect to the total attenuation of light. Both these effects, together with the possible chemical functionalization of carbon nanohorns, make this new kind of nanofluids very interesting for increasing the overall efficiency of the sunlight exploiting device. PACS 78.40.Ri, 78.35.+c, 78.67.Bf, 88.40.fh, 88.40.fr, 81.05.U.

The Mg2Si-based alloys are promising candidates for thermoelectric energy conversion for the middle high range of temperature. They are very attractive as they could replace lead-based compounds due to their low cost and non toxicity. They could also result in thermoelectric generator weight reduction (a key feature for the automotive application field). The high value of thermal conductivity of the silicide-based materials could be reduced by increasing the phonon scattering in the presence of nanosized crystalline grains without heavily interfering with the electrical conductivity of the thermoelectric material. Nanostructured materials were obtained under inert atmosphere through ball milling, thermal treatment and spark plasma sintering processes. In particular, the role of several bismuth doping amounts in Mg2Si were investigated (Mg2Si:Bi=1:x for x=0.01, 0.02 and 0.04 M ratio). The morphology, the composition and the structure of the samples were characterized by FE-SEM, EDS and XRD analyses after each process step. Moreover, the Seebeck coefficient analyses at high temperature and the electrical and thermal conductivity of the samples are presented in this work. The nanostructuring processes were affect by the MgO amount increase which influenced the thermoelectric properties of the samples mainly by reducing the electrical conductivity. With the aim of further increasing the scattering phenomena by interface or boundary effect, carbon nanostructures named Single Wall Carbon Nanohorns were added to the Mg2Si in order to produce a nanocomposite material. The influence of the nanostructured filler on the thermoelectric material properties is also discussed.

Nanotechnologies offer the opportunity to improve the characteristics of the oil and the oil–refrigerant mixture in refrigeration and air conditioning equipments by dispersing nanoparticles in the oil. Here a study of the influence of the dispersion of single wall carbon nanohorns (SWCNH) and titanium dioxide (TiO2) on the tribological properties of a commercial POE oil is presented, together with the effects on the solubility of R134a at different temperatures. The results obtained showed that the tribological behaviour of the base lubricant here considered can be either improved or worsen, depending on the property (anti-wear or extreme-pressure behaviour), by adding small amount of nanoparticles. On the other hand, nanoparticles dispersion in the base oil did not affect significantly the solubility, suggesting the independence of the thermodynamic properties of the oil from the presence of nanoparticles.

Impedance spectroscopy has been proposed as possible approach for non-invasive glycaemia monitoring. However, few quantitative data are reported about impedance variations related to glucose concentration variations, especially below the MHz band. Furthermore, it is not clear whether glucose directly affects the impedance parameters or only indirectly by inducing biochemical phenomena. We investigated the impedance variations in glucose-water and glucose-blood samples, for increasing glucose values (up to 300 mg/dl). In all the frequency range (0.1–107 Hz) glucose-water samples showed huge impedance modulus increases for increasing glucose values (up to 135%). In blood the impedance modulus showed only slight variations (2%), but again in a wide frequency range. Therefore: i) glucose directly affects the impedance parameters of solutions; ii) the influence on the impedance seems to decrease in high conductivity solutions, but it is still clearly present.

Impedance spectroscopy has been proposed as possible approach for non-invasive glycaemia monitoring. However, few quantitative data are reported about impedance variations related to glucose concentration variations, especially below the MHz band. Furthermore, it is not clear whether glucose directly affects the impedance parameters or only indirectly by inducing biochemical phenomena. We investigated the impedance variations in glucose-water, glucose-sodium chloride, and glucose-blood samples, for increasing glucose values (up to 300 mg/dl). In all the frequency range (0.1-10(7) Hz) glucose-water samples showed impedance modulus increases for increasing glucose values (up to 135%). In blood and sodium chloride samples the impedance modulus showed only slight variations (2% and 1.4%), but again in wide frequency ranges. Therefore: i) glucose directly affects the impedance parameters of solutions; ii) effects are more relevant at frequencies below the MHz band; iii) the influence on the impedance is decreased in high conductivity solutions, but still clearly present.