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A nanocatalyst with chiral amino alcohol catalytic function was efficiently employed in the Henry reaction, easily recovered by centrifugation and reused without loss of activity.

Fluorescent atomically precise Ag38(11-azido-2-ol-undecane-thiolate)24 nanoclusters are easily prepared using sodium ascorbate as a "green"reducer and are extensively characterized by way of elemental analyses, ATR-FTIR, XRD, SAXS, UV-vis, fluorescence spectroscopies, and theoretical modeling. The fluorescence and the atomically determined stoichiometry and structure, the facile and environmentally green synthesis, together with the novel presence of terminal azido groups in the ligands which opens the way to "click"-binding a wide set of molecular species, make Ag38(11-azido-2-ol-undecane-thiolate)24 nanoclusters uniquely appealing systems for biosensing, recognition and functionalization in biomedicine applications and in catalysis. This journal is

With the aim to easily recover and reuse the catalyst, an efficient amino alcohol catalyst previously tested in the asymmetric addition of diethylzinc to several aromatic aldehydes has been immobilized on proper functionalized superparamagnetic core-shell magnetite-silica nanoparticles and employed in the Henry reaction in the semi-homogeneous phase. The nanocatalyst exhibits a promising catalytic activity that remains unchanged in the three catalytic cycles performed. The results prove that highly efficient catalysts, by being immobilized on suitable magnetic nanosupports, can be easily recovered and reused, maintaining their catalytic behavior.

One of the options currently taken into account for the realization of the first DEMO reactor is the “water-cooled lanket”. This option implies an irradiation temperature for the blanket material in the range of 280–350 °C. Therefore, in light of the under irradiation behaviour of EUROFER, namely of the DBTT shift toward high temperature due to the low irradiation temperature embrittlement, the target of the hereby reported activities is the development of much tougher alloys, to try to tolerate the embrittlement due to the low irradiation temperature. We report in this paper the work done to optimize the toughness of Eurofer 97, increasing the normalizing temperature and maintaining a small grain size using multiple normalizing treatments. We report also the mechanical behaviour of two 9Cr1WTa type alloys, produced and tested with the same aim to find alloys more resistant to embrittlement at low irradiation temperature. Keywords: EUROFER 97, RAFM steels, Microstructure, Heat treatment, Tensile, Charpy, KLST

One of the options currently taken into account for the realization of the first DEMO reactor is the “water-cooled blanket”. This option implies a minimum irradiation temperature for the blanket material in the range of 280–350 °C. In addition to the DBTT (Ductile to Brittle Transition Temperature) shift due to the DPA (displacement per atom) damage under irradiation, also the issue of the increased embrittlement due to He production must be taken into account. This issue appears even more detrimental and less manageable because the DBBT shift due to the Helium production does not saturate with the dose, as it results from previous works reported in literature. The experimental results and the difference in behaviour between ODS (Oxide Dispersion Strengthened Steels) RAFM (Reduced Activation Ferritic Martensitic) and other FM (Ferritic Martensitic) alloys (EM10, P91) showed that it is possible to improve the resistance to He embrittlement by both intra-granular precipitation of Y-Ti oxides and by decreasing the grain size at the same time. Nevertheless, anyway, the multiplication of the grain boundaries increases the dilution of He on grain surface, delaying the formation of He bubbles on grain boundaries and, therefore, the susceptibility to the He embrittlement. Several grain size reduction strategies have then been investigated on EUROFER both at the austenitization stage, on the PAGS (Prior Austenite Grain Size), and at the tempering stage, on the tempered martensite. The microstructural observations have been carried out by means of SEM (Scanning Electron Microscopy). Also the effect of grain size reduction on the toughness of the material will be taken into account; The DBTTs resulting from impact tests on KLST specimens will be shown. The outcomes of the microstructural observations, as well as the preliminary mechanical characterization (impact tests) will be discussed in this paper. Keywords: EUROFER 97, RAFM steels, Microstructure, Multiple normalization, Asymmetric rolling, Recrystallization, KLST

Pyroelectric materials can harvest energy from naturally occurring ambient temperature changes, as well as from artificial temperature changes, notably from industrial activity. Wurtzite- based materials have the advantage of being cheap, non-toxic, and offering excellent opto-electrical properties. Due to their non-centrosymmetric nature, all wurtzite crystals have both piezoelectric and pyroelectric properties. Nanocrystalline wurtzite ZnS, being a room temperature stable material, by contrast to its bulk counterpart, is interesting due to its still not well-explored potential in piezoelectric and pyroelectric energy harvesting. An easy synthesis method—a co-precipitation technique—was selected and successfully tailored for nanocrystalline wurtzite ZnS production. ZnS nanopowder with nanoparticles of 3 to 5 nm in size was synthesized in ethyl glycol under medium temperature conditions using ZnCl2and thiourea as the sources of Zn and S, respectively. The purified and dried ZnS nanopowder was characterized by conventional methods (XRD, SEM, TEM, TG and FTIR). Finally, a constructed in-house pilot plant that is able to produce substantial amounts of wurtzite ZnS nanopowder in an environmentally friendly and cost-effective way is introduced and described.

Fluorescent atomically precise Ag

International audience; Ni60Co40 nanoparticles supported on γ-Al2O3 capable of simultaneously catalysing the steam reforming reaction of methane and supplying in-situ the heat necessary to activate the reaction by induction heating, have been synthesized and characterized. Energy is remotely and promptly supplied by an alternating radiofrequency magnetic field (induction heating system) to supported nanoparticles that act as dissipating agents by virtue of their ferromagnetic properties. The temperature reached on the Ni–Co based catalyst surface is high enough to obtain good catalytic performances for the steam methane reforming (SMR). By varying synthesis conditions, samples with two different metal loading (17 wt% and 30 wt%) and different particle size distribution were prepared and characterized. Experimental results evidence that the temperature reached on the catalyst surface is related to the metal loading and to the particles size distribution that strongly affect the ability of ferromagnetic nanoparticles to convert the externally applied radio frequency field into heat. Catalyst pellets proved their effectiveness reaching the temperature of 720 °C during SMR reaction and 80% methane conversion.

Noble metal thiolate nanoclusters are a new class of nanomaterials with molecular-like properties such as high dispersibility and fluorescence in the visible and infrared spectral region, properties highly requested in biomedicine for imaging, sensing and drug delivery applications. We report on three new silver phenylethane thiolate nanoclusters, differing for slight modifications of the preparation, i.e., the reaction solvent and the thiolate quantity, producing changes in the nanocluster composition as well as in the fluorescence behavior. All samples, excited in the range 250–500 nm, emit around 400 and 700 nm differing in the emission maxima and behavior. The silver thiolate nanoclusters have been characterized by way of C, H, S elemental analyses and Thermal Gravimetric Analysis (TGA) to determine the nanocluster composition, Scanning Transmission Electron Microscopy (STEM) to investigate the nanocluster morphology and UV-Vis and fluorescence spectroscopy to study their optical properties.

The Two-Step Sintering (TSS) process is a useful method to obtain sintered materials of high density and to limit the grain growth associated with the final stage of the sintering process. One of the main advantages of this method is the lowering of the sintering temperature. The development of bulk, dense and small grain size in the wurtzite phase of the ZnS ceramic was investigated by using a micron-sized ZnS powder as a precursor material. The microstructure and morphology of the TSS-fabricated ZnS ceramic pellets were observed by Scanning Electron Microscopy (SEM) and compared to those produced by the conventional sintering process. The ZnS ceramic produced using the TSS method at 1100°C showed comparable density and a much finer microstructure (five times smaller grain size) than the ZnS ceramic produced using conventional sintering at 1250°C. It was demonstrated that the TSS process is a pressureless, simple and cost‐effective sintering method, able to deliver high density bulk, wurtzite phase ZnS ceramics with controlled grain size. &nbsp

The pyroelectric performances of non-ferroelectric pyroelectrics like wurtzite- based materials (e.g. AlN, GaN, CdS or ZnO) make them important, although not widely used, compared to the current state-of-the-art ferroelectrics. Their high chemical and thermal stability allows their use at high temperatures in air, whereas ferroelectrics become ineffective when heated beyond their Curie temperature (TC). Wurtzite based materials have a higher thermal conductivity allowing them to react faster to ambient temperature changes, their raw material costs are lower and many of them are eco-friendly. Current pyroelectrics applications are limited to portable systems or tasks needing only μW–mW power. To be commercially viable, we must improve the current low efficiency of pyroelectric systems and intrinsically enhance the pyroelectric properties of modern materials through suitable doping or material engineering. We chose to study hexagonal wurtzite phase of ZnS, among the structurally simplest of pyroelectrics, as a possible energy harvesting material. An easy synthesis method – a co-precipitation technique, was tailored for nanocrystalline wurtzite ZnS production. This method is easy to scale-up and our next step is to build an in-house pilot plant that will produce substantial amounts of wurtzite ZnS nano-powder in an environmentally friendly and cost-effective manner. We further investigated the development of bulk, dense pyroelectric ceramics by the Two-Step Sintering (TSS) fabrication process, using as the precursor material both a micron-sized commercial powder of the ZnS cubic and hexagonal phases mixture, and an in-house produced wurtzite ZnS nanopowder. The TSS was chosen as being a pressureless, simple and cost‐effective sintering method for obtaining high density materials with controlled grain growth operating at a lower temperature than the conventiona process. Electron Microscopy techniques helped us to study the microstructure and morphology of both the precursor nanopowders and the obtained ceramics. Acknowledgement: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 797951.

Pyrolectric materials are able to harvest energy both from naturally and artificially occurring temperature changes. These materials could be the right way to recover some of the enormous amount of energy wasted as heat and help to develop new devices for harvesting thermal ambient energy. In this work it was investigated the development of bulk, dense pyroelectric ceramics, ideally with a highly developed texture and small grain size, using a micron-sized powder of the ZnS wurtzite phase as precursor material. The Two-Step Sintering (TSS) process is a useful method to obtain high sintered density and to limit the grain growth associated with the final stage of the sintering process. One of the main advantages of this method is the lowering of the sintering temperature. The microstructural, morphological and electrical properties of TSS-ZnS were determined and compared to ZnS produced by the conventional sintering process, performed at 1250°C. TSS-ZnS showed comparable density and a finer microstructure than conventional ZnS (five times lower grain size). It was demonstrated that the TSS process is a pressureless, simple and cost‐effective sintering method to obtain high density materials with controlled grain growth, without using a dopant or binder. The TSS produced ZnS ceramic was tested for pyroelectric energy harvesting. It is expected that the efficiency of the ceramic in harvested energy could be further improved by decreasing the grain size down to the nanoscale. Acknowledgement: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 797951.

Carbon nanostructures are achieved by bio-waste Allium cepa, L., (onion vulgaris) peels through pyrolysis at 900 &deg, C. They contain dispersed elements derived by their bio-precursors, like Mg, Ca, S, Na, K, and Cu. Here, we report the self-assembly of new Cu flower-shaped nanostructures organized as nano-roses. Remarkably, the nano-roses show rolled-up petals of Cu0 with a high chemical stability in air, exhibiting an intrinsic pure Cu crystalline phase. This suggests the exceptional potentiality to synthesize Cu0 nanostructures with novel physical/chemical properties. The size, morphology, and chemical composition were obtained by a combination of high-resolution scanning electron microscopy, energy dispersive X-ray spectroscopy, energy dispersive X-ray diffraction, and Raman spectroscopy.

A linear β-amino alcohol ligand, previously found to be a very efficient catalyst for enantioselective addition of dialkylzinc to aromatic aldehydes, has been anchored on differently functionalized superparamagnetic core-shell magnetite-silica nanoparticles (1a and 1b). Its catalytic activity in the addition of dialkylzinc to aldehydes has been evaluated, leading to promising results, especially in the case of 1b for which the recovery by simple magnetic decantation and reuse was successfully verified. This journal is

Ten Eurofer97 steel variants, produced by non-standard fabrication-processing routes and modified alloying chemistries, were studied by neutron irradiations in the high flux isotope reactor. The irradiations were performed to ITER-TBM relevant conditions of ∼255–350 °C, 2.94–3.24 dpa. We quantified the irradiation-induced degradation of the steels using mechanical property tests. All the steels suffered from irradiation hardening, where a significant increase in Vickers microhardness and yield stress (σYS) occurred, accompanied with severe loss of tensile elongation. The extent of hardening was material dependent. For Tirr = 300±30 °C, most steels showed σYS increase in the range of ∼30% to as high as ∼66%, except for a low temperature tempered steel with σYS increase below 15%. Despite large losses in elongation, most failures were ductile. Significant post-necking ductility was retained with reduction in area (RA) between 65–75%, but

Presently available data on neutron irradiation damage raise doubts on the feasibility of using EUROFER97 steel for a water-cooled starter blanket in a DEMO reactor, since the ductile-to-brittle transition temperature (DBTT) increases significantly for irradiation temperatures below 350°C. The additional DBTT shift caused by H and He transmutation can only be estimated based on very few results with isotopically tailored EUROFER97 steel. Conservative calculations show that the DBTT of EUROFER97 steel could exceed the operating temperature in water-cooled starter blankets within a relatively short time period. This paper presents results from a EUROfusion funded irradiation campaign that was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. The paper compares ten newly developed reduced activation ferritic-martensitic (RAFM) steels irradiated to a nominal dose of 2.5 dpa at 300°C. The post-irradiation experiments using Small Specimen Test Technology included hardness, tensile, and fracture mechanics tests combined with fractography and microstructure analysis are presented. Results show that micro-alloying EUROFER97-type steels influenced the mechanical properties but a dominating impact on irradiation damage resistance could not be identified. In contrast, specific thermo-mechanical treatments lead to better DBTT behavior. Discussion about irradiation response to heat treatment conditions is also given. Despite requiring data also at high dpa values, the results indicate that with these modified materials an increased lifetime and potentially also an increased operating temperature window can be achieved compared to EUROFER97.

Ultrathin stable transparent conductive nickel films were deposited on quartz substrates by radio frequency sputtering at room temperature. Such films showed visible transmittance up to 80% and conductivity up to 1.8 × 104 S/cm, further increased to 2,3 × 105 S/cm by incorporation of a micrometric silver grid. Atomic force microscopy and scanning electron microscopy revealed quite compact, smooth and low surface roughness films. Excellent film stability, ease, fast and low cost process fabrication make these films highly competitive compared to indium tin oxide alternative transparent conductors. Films were characterized regarding their morphological, optical and electrical properties. © 2015 Elsevier B.V.

Among the options currently taken into account for the realization of the first DEMO reactor there are the “helium-cooled” and the “dual coolant” breeding blanket. Therefore the high temperature (650 °C) behavior of the proposed innovative martensitic alloys should be improved, namely the frame of the hereby reported activities is the development of martensitic alloys more resistant to creep, suitable to tolerate such a high operating temperature. In order to improve the high temperature mechanical properties, concerning the alloy design strategies, two alternative routes are proposed; the effect of Nitrogen and Tungsten increase are taken into account as well as the addition of carbo-nitride forming elements, like Vanadium, combined with the “ausforming” thermo-mechanical treatments. Two alloys have been designed and a special thermo-mechanical treatment on Eurofer 97-2 is proposed. The “ausforming” treatment, consisting in a sort of hot-working at a lower temperature with respect to the austenitization one after the austenitization stage, is aimed at the achievement of a beneficial dislocation “pinning” at high temperature due to carbide precipitation. Generally the improvement of tensile properties is associated to the hardening of the steel due to dislocation network and precipitation effects. This hardening is accompanied by a DBTT increase to markedly higher values with respect to Standard Eurofer. The proposed materials should be, in any case, at least room temperature ductile in order to undergo safe manufacturing and assembling processes. Therefore the issue of the DBTT increase has been taken into account by tuning the tempering temperature adequately. The two variations from chemical composition of Eurofer 97 have been casted and the thermo-mechanical treatments have been selected by means of SEM and hardness measurements to tune grain size and precipitation of carbides. The outcomes of the preliminary mechanical characterization (tensile, creep and impact tests) will be discussed in this paper. Keywords: EUROFER 97, RAFM steels, Thermo-mechanical treatment, Ausforming, Tensile, Creep, Charpy

We show that using the same reaction procedure, by hindering or allowing the formation of a reaction intermediate, the Ag+dodecanethiolate polymeric complex, it is possible to selectively obtain Ag dodecanethiolate nanoparticles or Ag dodecanethiolate nanoclusters in the size range 4-2 nm. Moreover, the Ag dodecanethiolate nanoclusters display a lamellar superstructure templated from the precursor Ag+dodecanethiolate polymeric complex. A plausible formation mechanism is illustrated where, starting from the precursor and scaffold lamellar Ag+ thiolate polymeric complex, first the nanocluster Agn 0 core is formed by reduction of isoplanar Ag+ ions, followed by Ag+ thiolate units that build protection, the nanocluster shell, around the core. The nanoclusters are characterized by elemental analyses, XRD, ATR-FTIR, XPS, XAS, MALDI, ESI, UV-Vis and fluorescence measurements. The luminescent Ag15(dodecanethiolate)11·2H2O nanocluster is achieved in good yield after 4 hours of reaction whereas after 2 hours, the luminescent Ag35(dodecanethiolate)16 is isolated. Both Ag nanoclusters present emission bands in the range 330-450 nm, the shifting depending on the excitation wavelength. This phenomenon is attributed to a possible dipolar state causing distribution in energies due to variability of dipole-dipole interactions. Moreover, both nanoclusters further present a NIR emission at about 700 nm independent from the excitation wavelength. Thanks to their optical and structural properties, the synthesized nanoclusters, perfect molecular/nanoparticle hybrids, have great potentiality for new applications in nanotechnologies. © 2018 The Royal Society of Chemistry.

Eurofer97 steel has been recognised in Europe as the reference steel for nuclear application under high radiation density. Following to this a detailed knowledge of microstructure evolution is required for such steel after thermo-mechanical processing. In this paper the effect of thermo-mechanical parameters on the mechanical behavior of Eurofer97 was investigated by hot rolling and heat treatment on pilot scale. Results show a strong effect was found of reheating temperature before rolling on the material hardness, due to an increase of hardenability following the austenite grain growth. A minor effect was found of the hot reduction and the tempering temperature in the total investigated deformation range. A loss of impact energy was found coupled with the hardness increase. © 2018 Andrea Di Schino et al., published by De Gruyter.

Angular stability locking plates are commonly used in proximal humeral fractures, especially in old patients with osteoporotic bones. These implants show good results in short and midterm follow-up, but complications are not uncommon. Here we present a case report to describe a case of early failure of a proximal angular stability plate implanted in a 72 years old female with a highly unstable two part proximal humeral fracture. An optical and metallurgic analysis was also conducted to study the modalities of failure. We concluded that anatomic reduction and restoration of the medial cortical support are crucial in order to minimize the mechanical load on the bone–metal interface and to prevent mechanical failure, in particular when the fracture rim drop in the weak point of the plate that was found in the proximal two symmetric holes (Holes E). Keywords: Proximal humerus fracture, Plate failure, Angular stability locking plate, Metallurgic plate analysis

MCrAlY coatings are usually adopted to improve the environmental resistance of Ni-based superalloy components of turbine engines against high-temperature oxidation and hot corrosion. In this work, CoNiCrAlYRe coatings were produced by atmospheric plasma spraying. The coatings exhibited relatively low oxygen content and porosity. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy analyses revealed that the high-temperature exposure at 1383ﾠK (1110ﾠﾰC) promoted the growth of an oxide scale on the top surface being composed of a continuous and dense Al2O3 inner layer followed by an outer mixed layer (Cr2O3 and spinels). The oxide scale was mainly composed of Al2O3, while the formation of mixed oxides occurred at lesser extent. After high-temperature exposure, the formation of internal oxides in some areas reduced the inter-lamellar cohesion, so that a decrease in microhardness was found.

FePt nanoparticles, containing a near-equal atomic percentage of Fe and Pt, with a face centered tetragonal structure ( fct ), are challenging for potential applications in high performance permanent magnets and high density data storage. In this study, we report on the chemical synthesis, carried out both solvothermally and hydrothermally in autoclave reacting iron (III) acetylacetonate and platinum (II) acetylacetonate with tri- or tetra-ethylene glycol, these employed as solvents, reducers and particle surface protecting agents as well. In both methods, a subsequent thermal treatment at high temperatures is necessary to transform the magnetic soft face centered cubic ( fcc ) phase to the hard fct one. Organic low-weight molecules, generally used to protect the nanoparticle surface and avoid particle aggregation, are decomposed by the thermal treatment resulting in particle aggregation and coalescence phenomena; on the contrary, in this case, a polymer matrix is formed as particle protecting agent and, by thermally treating the hydrothermally prepared nanoparticles up to 750 °C for 1 h, the pure magnetic hard fct phase is obtained while preserving the nanostructure. A detailed study is carried out on FePt nanoparticle structure ( fcc and fct phases) and correlated to the magnetic properties of the system.

Nanocomposites formed by hard and soft magnetic phases are very promising for magnetic energy storage and biomedical applications. Highly challenging is the development of simple synthesis methods able to tune the phase composition and a thorough structural, morphologic and magnetic characterization in order to understand and optimize the interactions between hard and soft magnetic phases. Mainly depending on Fe:Pt atomic ratio, multi-phase or single phase FePt nanocomposites have been prepared by thermal treatment of core–shell FePt(Ag)@Fe 3 O 4 nanoparticles at 750 °C for 1 h under flow of a Ar + 5% H 2 gas mixture (H 2 is necessary to reduce Fe 2+ and Fe 3+ ions of Fe 3 O 4 to Fe 0 atoms and the thermal treatment to form the crystalline soft and hard magnetic FePt phases). Performing Rietveld refinement of the XRD data as well as HR-TEM and electron diffraction analyses, the different phases have been singled out. Besides single phase hard L1 0 FePt and soft magnetic L1 2 Fe 3 Pt nanoparticles, two phase soft α-FePt and γ-FePt and hard and soft magnetic L1 0 FePt and L1 2 FePt 3 nanocomposites have been formed and the structure and morphology correlated to their magnetic behavior. Moreover, for possible applications, it is important to form stable nanoparticle layers; as-prepared FePt(Ag)@Fe3O 4 nanoparticles have been chemically attached on a Si substrate, thermally annealed and the morphology, structure and magnetic properties of the layered nanoparticle sample investigated.

Highly conductive and transparent NiOx films can be very useful as buffer layers for the optimization of the p-type contacts of optoelectronic devices. Thin NiOx films were fabricated by reactive radio frequency (RF) sputtering at room temperature starting from a Ni target. A systematic study of the influence of oxygen partial pressure, RF power and sputtering gas pressure on the films' properties was carried out. The structural, microstructural, optical and electrical properties were affected differently by the sputtering parameters. Resistivity decreased by increasing the oxygen partial pressure and the sputtering total pressure and by decreasing the RF power, while transmittance increased by decreasing the oxygen partial pressure and by increasing the RF power and sputtering pressure. Minimum resistivity of 1.6 × 10-2 Ωcm and a visible transmittance of 40% were achieved for a film grown in a pure oxygen atmosphere, while a higher transmittance of 54% and a resistivity of ρ = 1.1×10-1 Ωcm were obtained for a film grown at 30% oxygen partial pressure. The trends of transmittance and resistivity as a function of the oxygen pressure during the sputtering process can be explained in terms of the amount of Ni3+ defects deduced by x-ray photoelectron spectroscopy (XPS) measurements. The full interpretation of the other results is less straightforward and highlights the relevance of the samples' structural properties. © 2016 IOP Publishing Ltd.

Atmospheric plasma spraying of WC-Co particles with standard gas mixtures (Ar-H2) typically results in largely decarburized coatings with relatively low wear resistance. To fabricate cermet coatings with enhanced tribological properties, nanostructured WC-Co coatings were plasma sprayed using two different process gas mixtures. Phase composition and microstructure were investigated by X-ray diffraction and scanning electron microscopy, respectively. Microhardness increased by increasing the amount of retained WC grains in coating microstructure. Friction and wear properties, measured under dry sliding conditions, strongly depended on the degree of decarburization. They were comparable to those of conventional coatings produced using identical conditions. © 2012 The American Ceramic Society.

Polycrystalline, close-packed, homogeneous nanostructured ceria thin films were prepared by sol–gel process via dip-coating technique on soda-lime glass and (100)-oriented Si substrates. To produce the films, a sol was prepared using, as precursor, a home made cerium sec-butoxide dissolved in secondary butanol. The chemical composition, the microstructural/morphological characteristics and the optical properties of the coatings were investigated in detail. The experimental results clearly demonstrate that the ceria films are nanocrystalline (CeO2, cubic phase $$ {\text{Fm}}\bar{3}{\text{m}} $$ ) with an average grain size of about 2–3 nm for the samples grown on glass and of about 4–5 nm for the samples grown on silicon. The analyses of ceria layers grown on silicon show that the ceria coatings are free from organic residues and that a Si-oxide layer is formed at the film/substrate interface. The optical results evidence a red shift of the energy gap of about 0.5 eV that can be ascribed to conversion of relevant Ce4+ sites to Ce3+ sites and a consequent creation of oxygen vacancy at the surface of the ceria grains.

Thick mullite (3Al 2 O 3 –2SiO 2 ) coatings were fabricated by atmospheric plasma spraying (APS) in a mixture of crystalline and amorphous phases, as confirmed by X-ray diffraction (XRD) analysis. The coatings were isothermally heat treated in order to study recrystallization mechanism of the glassy phase. The morphology and the microstructure of both mullite feedstock and coatings were investigated by using scansion electron microscopy (SEM). The porosity of as-sprayed coating was in the range between 2 and 3% and substantially remained unchanged after thermal treatment. The thermal expansion of as-sprayed and annealed coatings was measured during heating up to the temperature of crystallization and the corresponding high-temperature extent of shrinkage was calculated. The differential scanning calorimetry (DSC) curves at different heating rates showed a sharp exothermic peak between 1243 and 1253 K, suggesting a rapid recrystallization of the amorphous phase. Finally, the heat capacity of recrystallized mullite coating was measured by DSC experiments. It was approximately 1.02 × 10 3 J/kg K at 373 K and increased with increasing test temperature.

The sorption behavior of MgH2 is the subject of numerous investigations concerning the safe hydrogen storage in metallic hydrides. With the purpose of integrating kinetic studies on the MgH2–Mg phase transformation with the analysis of the local microstructure, we have developed an experimental method for the metallographic examination by Scanning Electron Microscopy of partially desorbed MgH2 powders. The setting of the microscope and the sample preparation procedure have been optimized for highest contrast between Mg and MgH2, based on different electron emissions. In these experimental conditions the two phases can be clearly detected even in critical condition when strongly scattering catalyst particles are present. The method has been tested on a set of ball milled MgH2 samples either pure or containing Fe as catalyzing agent. A complete information on the spatial distribution of all the phases constituting the sample can be obtained by integrating observations carried out at different primary beam energies with different signals. As far as the desorption behavior is concerned, SEM analysis shows that the MgH2–Mg phase transition is strongly affected by catalyst particles which, in the present case, appear to support the nucleation step in the phase transformation sequence.

Atmospheric plasma spraying of WC coatings is typically characterized by increased decarburization, with a consequent reduction of their wear resistance. Indeed, high temperature and oxidizing atmosphere promote the appearance of brittle crystalline and amorphous phases. However, by using a high helium flow rate in a process gas mixture, plasma spraying may easily be optimized by increasing the velocity of sprayed particles and by reducing the degree of WC dissolution. To this purpose, a comparative study was performed at different spray conditions. Both WC-Co powder and coating phases were characterized by X-ray difraction. Their microstructure was investigated by scanning electron microscopy. Mechanical, dry sliding friction, and wear tests were also performed. The wear resistance was highly related to both microstructural and mechanical properties. The experimental data confirmed that high-quality cermet coatings could be manufactured by using optimized Ar-He mixtures. Their enhanced hardness, toughness, and wear resistance resulted in coatings comparable to those sprayed by high velocity oxygen-fuel.

An electrochemical method for the Pt nanoparticles deposition on porous and high surface carbon substrates (carbon black and carbon nanotubes), as an alternative way to prepare gas diffusion electrodes for polymer electrolyte fuel cells (PEFCs), is herein described. Pt nanoparticles well distributed and localized on the electrode surface were obtained by using an electric field. The electro-catalysts were prepared by single and multiple pulse galvanostatic polarizations in 1 M sulphuric acid + 5 mM exachloroplatinic acid solution. Chemical analysis, cyclic voltammetry and field emission gun scanning electron microscopy were used to determine the electrochemical features of Pt deposits and the influence of electro-deposition method on their nano-morphology. Electro-catalytic performances were studied by investigating the methanol oxidation reaction and the results are presented in form of surface specific activity and mass specific activity to take into account the electrochemical real surface and Pt loading. A comparison with commercial E-TEK Pt/C catalysts, prepared by traditional chemical reduction and heat treatment in hydrogen, shows that the electrodeposited catalyst presents higher activity at lower Pt loading.

Hydrogen embrittlement (HE) of Eurofer’97 was investigated by means of constant extension rate tensile (CERT) and fully reversed load-control low cycle fatigue (LCF) tests, run at room temperature and under electrochemical charging before and during specimen deformation. Increasing H content from 1.6 to 5.6 wppm caused increasing ductility loss compared to air behaviour and increasing data scatter from replicated CERT tests in terms of embrittlement indexes and fracture modes. The same trend manifested itself on Eurofer fatigue lifetimes after cyclic loading below the monotonic yield, but to a major degree as frequency was lowered. Fractographic analysis under scanning electron microscope indicated that brittle cracking, which macroscopically involved intergranular (IG) or transgranular (TG) separation, included morphologies closely related to HE phenomena through plastic flow modification and/ or interface decohesion. Correlation of these results with H desorption spectra and microstructural assessments suggested that the origin of mechanical response variability from specimen-to-specimen with similar H levels could arise from material heterogeneity in terms of trap characteristics.

The aim of the Bias Enhanced Nucleation (BEN) step is to increase the nucleation density during the CVD diamond growth process with respect to more traditional methods like scratching. Diamond seeds were grown in a HFCVD reactor with several vertical straight filaments and a double bias geometry allowing BEN over large area silicon substrates. The effect of the substrate temperature and the gas composition was studied. Spectroscopic and morphological characterisation has been performed on the substrates, both after the BEN and the subsequent growth process. The substrate temperature was found to be an important parameter controlling the nucleation. When the substrate temperature is above 1100 °C, both the nucleation and the growth resulted in nanocrystalline SiC while at lower temperature optimal diamond nucleation and growth were found. Simultaneously, intermediate phases between elemental and non-stoichiometric SiC were observed by XPS. Nucleation densities of 10 11 cm −2 and higher were obtained over a surface of several squared centimeters.

The aim of this work is to measure the hydrogen transport and solubility parameters in the commercial alumina. Measurements are conducted using a time-dependent permeation method over the temperature range 1273–1673 K with hydrogen driving pressures in the range 104–105 Pa (100–1000 mbar). A half-power pressure dependence (diffusion-limited permeation) of the permeation flux for alumina is observed. The Arrhenius expressions for the hydrogen permeability, diffusivity, and Sieverts' constant values obtained from a fitting to the whole temperature range are as follows: P=3.3·10−10 exp(−97420/RT) mol·m−1·s−1·Pa−1/2 D=9.7·10−8 exp(−79990/RT) m2·s−1 Ks=5.5·10−3 exp(−22540/RT) mol·m−3·Pa−1/2

Carbon nanotubes (CNTs) were grown on nickel catalysts by hot filament chemical vapour deposition (HFCVD) using H 2 and CH 4 as gas precursors. CNTs with different characteristics were observed varying some growth parameters, such as the substrate temperature, the total pressure and the methane concentration. These parameters were optimised in order to obtain untangled CNTs with high density and smooth walls. Catalyst nanoparticles were obtained through the clustering of Ni thin films deposited by sputtering techniques. CNTs grown on samples with the silicon native oxide or with a SiO 2 coating between Si substrate and Ni film were compared. Catalytic layers and CNTs were characterised by SEM and XPS.

One-phase, one-pot synthesis of Ag(0) nanoparticles capped with alkanethiolate molecules has been optimized to easily achieve a pure product in quantitative yield. We report the synthesis of dodecanethiolate-capped silver particles and the chemophysical, structural, and morphologic characterization performed by way of UV-vis, (1)H NMR, and X-ray photoelectron (XPS) spectroscopies, X-ray powder diffraction (XRD) and X-ray absorption fine structure analysis (XFAS), electron diffraction and high-resolution transmission electron microscopy (HR-TEM), and scanning and transmission electron microscopy (SEM and TEM). Depending on the molar ratio of the reagents (dodecylthiosulphate/Ag(+)), the mean Ag(0) particle size D(XRD) is tuned from 4 to 3 nm with a narrow size distribution. The particles are highly soluble, very stable in organic solvents (hexane, toluene, dichloromethane, etc.), and resistant to oxidation; the hexane solution after one year at room temperature does not show any precipitation or formation of oxidation byproducts.

Chemical Vapour Infiltration (CVI) technique has been long used to produce carbon/carbon composites. The Pyrolytic Carbon (Py-C) matrix infiltrated by CVI could have different microstructures, i.e. Rough Laminar (RL), Smooth Laminar (SL) or Isotropic (ISO). These matrix microstructures, characterized by different properties, influence the mechanical behaviour of the obtained composites. Tailoring the process parameters, it is possible to direct the infiltration towards a specific Py-C type. However, the factors, influencing the production of a specific matrix microstructure, are numerous and interconnected, e.g. temperature, pressure, flow rates etc. Due to the complexity of the physical and chemical phenomena involved in CVI process, up to now it has not been possible to obtain a general correlation between CVI process parameters and Py–C microstructure. This study is aimed at investigating the relationship between infiltration temperature and the microstructure of obtained Py-C, for a pilot - sized CVI/CVD reactor. Fixing the other process parameters and varying only the temperature, from 1100°C to 1300°C, the Py-C infiltration was performed on fibrous preforms. Polarized light microscopy, with quantitative measurements of average extinction angle (Ae), and Raman spectroscopy were used to characterize the obtained Py-C microstructures.

Properties of consolidant and protective materials modified with nanoparticles were analysed in this study following their application onto marble samples. For this purpose, different solutions of an acrylic resin with dispersed SiO2 and TiO2 nanoparticles were prepared. The relative durability of Paraloid B72, an acrylic resin used as consolidant and modified by nanoparticles, was evaluated comparatively by means of diverse diagnostic techniques, namely, scanning electron microscopy, laser-induced fluorescence, ultrasonic sound, colorimetry, total immersion water absorption and contact angle. The results demonstrate that nanoparticles enhance the effectiveness of consolidant and protective material because they induce substantial changes of surface morphology of the coating layer.

In this work, the effectiveness of nanocomposite surface treatments as protective systems for artistic stones was evaluated. Pyrolitic silica and titania nanoparticles were dispersed in a commercial silicon-based polymer and applied on marble and travertine samples. Artificial aging processes, both in climatic chamber and in solar box, were carried out to simulate real degradation processes in terms of photo-thermal effects and physical-chemical damage. The performances of the nanocomposites used as consolidant were evaluated comparatively by means of diverse diagnostic techniques, namely: scanning electron microscopy (SEM), laser induced fluorescence (LIF), ultrasonic technique, colorimetry, total immersion water absorption and contact angle. The results show that some properties of conservation materials can be improved by the presences of nanoparticles because they induce substantial changes of surface morphology of the coating layer and counter the physical damage observed during artificial weathering. © 2014 AIP Publishing LLC.

Gamma-ray irradiations induced various alterations in sulfur- and selenium-based chalcogenide glasses. The absorbed dose was in the range of 0.01–3.6 MGy. The glasses exhibit prominent sensitivity to γ-ray irradiation, characterized by changes in some of the physical properties of the glasses, e.g., optical transmission, optical band gap, density, and thermal expansion coefficient. The effects on glass structure and microscopic morphology were also studied by Raman spectra and scanning electron microscopic observations.

Hydrophilic magnetite nanoparticles in the size range 30–10 nm are easily and rapidly prepared under ultrasonic irradiation of Fe(OH) 2 in di- and tri-ethylene glycol/water solution with volume ratio varying between 7:3 and 3:7. Structural (XRD) and morphological (SEM) characterization reveal good crystalline and homogeneous particles whereas, when solvothermally prepared, the particles are inhomogeneous and aggregated. The sonochemically prepared particles are versatile, i.e. well suited to covalently bind molecules because of the free glycol hydroxylic groups on their surface or exchange the diethylene or triethylene glycol ligand. They can be easily transferred in hydrophobic solvents too. Room-temperature magnetic hysteresis properties measured by means of Vibrating Sample Magnetometer (VSM) display a nearly superparamagnetic character. The sonochemical preparation is easily scalable to meet industrial demand.

Poly(etherether-ketone)-alumina coating were deposited by EPD. In order to densify the coatings, conventional thermal treatments were performed at a temperature equal or higher than the melting point of the polymer. The samples treated at the lower temperature showed an increase in the quality of crystallinity of the polymer. As an alternative method, an excimer laser was used to treat the surface of the composite coatings. The laser beam irradiation did not induce any modification in the crystalline structure of the polymer and at the same time did not produce strong degradation of the polymer molecule, also when the laser beam fluence was higher than the ablation limit. The most relevant modification induced by both the treatments was a change in the morphology and the porosity.

Nanostructured titania thin films were prepared under controlled atmospheric conditions by the sol–gel dip-coating technique on glass, fused silica and (1 0 0)-silicon substrates. Two different sol–gel routes were employed by using different precursor solutions, a highly acid solution and a polymer-like solution. The influence of sol composition and of the substrate type on the morphology, coating porosity, surface roughness, crystalline phases and grain size of the titania films were investigated in detail. In addition, the relationship between microstructural/morphological properties and the optical properties (energy gap, refractive index and extinction coefficient) and the hydrophilic performance of the coatings were evaluated. Our experimental results clearly indicate that the sol composition and substrate type remarkably influence the films' morphology and microstructure; moreover, they consequently modify the optical response and hydrophilic performances of the samples, showing that superhydrophilic titania coatings can be obtained opportunely by choosing the composition of the precursor sol–gel solution. Blue shift of the band gap energy and a band structure mutation from indirect to direct were also revealed. The hydrophilic properties and the change in the band gaps transition can be attributed to oxygen vacancies on the surface of the titania nanocrystallites that gives rise to Ti3+ sites and, consequently, to structural changes/defects of the anatase nanoarchitecture. These findings allow us to design and tailor the optical and hydrophilic properties of the titania coatings.

AB5 metal hydride (MH) particles were polymer dispersed in order to entrap the micro and nanoparticles produced by repeated fragmentations of the metal phase during the hydrogen charging/discharging cycles. Acrylonitrile-butadiene-styrene copolymer (ABS) was selected as a matrix on the basis of its physical and chemical properties. AB5/ABS composite pellets were obtained by using a dry mechanical particle coating approach in a tumbling-mill apparatus and successive consolidation by uniaxial hot pressing. A number of characterization techniques were used to assess the morphological, chemical and structural properties of the composites. High pressure DSC measurements, conducted at different pressure values, were used to assess the H2 absorption properties and profile the Van't Hoff plots of the material. The overall results indicated that the AB5/ABS composite well tolerated the hydriding effects on metal particles, with no losses in hydriding kinetics. The material characteristics were found to be compatible with its application in developing MH-based H2 storage devices.