Netherlands Organization for Scientific Research NWO

Grenoble, France

Netherlands Organization for Scientific Research NWO

Grenoble, France

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Portale G.,Netherlands Organization for Scientific Research NWO | Carbone A.,CNR Institute of Advanced Energy Technologies Nicola Giordano | Martinelli A.,University of Rome La Sapienza | Passalacqua E.,CNR Institute of Advanced Energy Technologies Nicola Giordano
Solid State Ionics | Year: 2013

A detailed study of the microstructure, the transport properties and the state of water for fluorine-free sulfonated poly(ether ether ketone) (s-PEEK) membranes with a degree of sulfonation of about 50% is reported as a function of the membrane water content. SAXS curves show how 50% s-PEEK membranes at low and intermediate water contents are characterized by a poor hydrophobic/ hydrophilic phase-separation and narrow ionic domains (< 2 nm). For membrane water contents of up to 40%, all the water molecules contained in the membranes appear to be strongly bounded to the sulfonic groups and water molecules are unable to freeze. When the membranes are treated in water at temperatures higher than 80 C, membrane swelling starts and for water contents above 40-50% a better ionic microstructuring inside the membranes occurs. In highly swollen membranes part of the water molecules is in a less associated freezable bounded state. The presence of more mobile water molecules is responsible for the increase in the membrane proton conductivity and conductivity of the order of 0.1 S/cm has been recorded for s-PEEK with 69% of water content. © 2013 Elsevier B.V.


Martis V.,Netherlands Organization for Scientific Research NWO | Martis V.,University College London | Nikitenko S.,Netherlands Organization for Scientific Research NWO | Sen S.,University of California at Davis | And 6 more authors.
Crystal Growth and Design | Year: 2011

The effects of exposure to a monochromatic 10 keV X-ray beam on thermally induced crystallization of lithium disilicate glass have been investigated and rendered two unexpected findings. First, it was found that an extended exposure during the nucleation heat treatment increased the number of nucleation sites. Second, it was observed that the effects extended far beyond the sample region that was directly exposed to the X-ray beam. The effects were confined to the direction perpendicular to the polarization of the synchrotron radiation beam that was used. The effects could be attributed to photo electrons created not only by the direct X-ray beam but also by the scattered radiation. Further evidence of the influence of photo electrons due to scattered X-rays is found in the results of an online crystallization study on a lysozyme solution. © 2011 American Chemical Society.


Ryan A.J.,University of Sheffield | Bras W.,Netherlands Organization for Scientific Research NWO | Hermida-Merino D.,Netherlands Organization for Scientific Research NWO | Cavallo D.,University of Genoa
Journal of Non-Crystalline Solids | Year: 2016

The crystallization of polymers from the amorphous melt is a challenging field in which the material is subjected to changes in a combination of rapidly varying parameters in order to induce solidification with a controlled degree of crystallinity as well as maintain control over the macroscopic shape as well as semi-crystalline structure and orientation. The challenge lies in both the academic understanding as well as in the difficulty to reach industrially relevant conditions whilst obtaining the experimental data that can shed light on the processes governing the different competing physical processes that play a role during the processing.The development path of this type of research from the early time-resolved synchrotron radiation X-ray based to the current state of the art experiments is discussed. © 2016 Elsevier B.V.


Sciortino L.,University of Palermo | Giannici F.,University of Palermo | Martorana A.,University of Palermo | Ruggirello A.M.,University of Palermo | And 4 more authors.
Journal of Physical Chemistry C | Year: 2011

Cobalt-nickel bimetallic nanoparticles were synthesized by changing the sequence of the chemical reduction of Co(II) and Ni(II) ions confined in the core of bis(2-ethylhexyl)phosphate 2, and Ni(DEHP) 2. The reduction was carried out by mixing, sequentially or contemporaneously, fixed amounts of n-heptane solution of Co(DEHP) 2 and Ni(DEHP) 2 micelles with a solution of sodium borohydride in ethanol at a fixed (reductant)/(total metal) molar ratio. This procedure involves the rapid formation of surfactant-coated nanoparticles, indicated as Co/Ni (Co after Ni), Ni/Co (Ni after Co), and Co + Ni (simultaneous), followed by their slow separation as nanostructures embedded in a sodium bis(2-ethylhexyl)phosphate matrix. The resulting composites, together with those obtained by reducing the n-heptane solutions of pure Co(DEHP) 2 or Ni(DEHP) 2, were characterized by XPS, EXAFS, WAXS, and SAXS. The data analysis confirms the presence of nanometer-sized surfactant-coated cobalt, nickel, and cobalt/nickel particles. As expected, the composition and internal structure of cobalt/nickel bimetallic nanoparticles are influenced by the preparation sequence as well as by the "chemical affinity" between the surfactant and the metal. However, some atomic-scale physicochemical processes play a subtle role in determining the structural features of bimetallic nanoparticles. Further effects due to the competition between nanoparticle growing process and surfactant adsorption at the nanoparticle surface were observed. © 2011 American Chemical Society.


Li D.Y.,Catholic University of Leuven | Zeng Y.J.,Catholic University of Leuven | Batuk D.,University of Antwerp | Pereira L.M.C.,Catholic University of Leuven | And 10 more authors.
ACS Applied Materials and Interfaces | Year: 2014

ZnO-Co nanocomposite thin films are synthesized by combination of pulsed laser deposition of ZnO and Co ion implantation. Both superparamagnetism and relaxor ferroelectricity as well as magnetoelectric coupling in the nanocomposites have been demonstrated. The unexpected relaxor ferroelectricity is believed to be the result of the local lattice distortion induced by the incorporation of the Co nanoparticles. Magnetoelectric coupling can be attributed to the interaction between the electric dipole moments and the magnetic moments, which are both induced by the incorporation of Co. The introduced ZnO-Co nanocomposite thin films are different from conventional strain-mediated multiferroic composites. © 2014 American Chemical Society.


Longo A.,CNR Institute of Nanostructured Materials | Longo A.,Netherlands Organization for Scientific Research NWO | Sciortino L.,University of Palermo | Giannici F.,University of Palermo | Martorana A.,University of Palermo
Journal of Applied Crystallography | Year: 2014

The properties of nanostructured cobalt in the fields of magnetic, catalytic and biomaterials depend critically on Co close packing. This paper reports a structural analysis of nanosized cobalt based on the whole X-ray diffraction (XRD) pattern simulation allowed by the Debye equation. The underlying structural model involves statistical sequences of cobalt layers and produces simulated XRD powder patterns bearing the concurrent signatures of hexagonal and cubic close packing (h.c.p. and f.c.c.). Shape, size distribution and distance distribution between pairs of atoms are also modelled. The simulation algorithm allows straightforward fitting to experimental data and hence the quantitative assessment of the model parameters. Analysis of two samples having, respectively, h.c.p. and f.c.c. appearance is reported. Extended X-ray absorption fine-structure (EXAFS) and X-ray absorption near-edge structure (XANES) spectra are simulated on the basis of the model, giving a tool for the interpretation of structural data complementary to XRD. The outlined structural analysis provides a rigorous structural basis for correlations with magnetic and catalytic properties and an experimental reference for ab initio modelling of these properties. © 2014 International Union of Crystallography.


Portale G.,Netherlands Organization for Scientific Research NWO | Sciortino L.,University of Palermo | Albonetti C.,CNR Institute of Nanostructured Materials | Giannici F.,University of Palermo | And 5 more authors.
Physical Chemistry Chemical Physics | Year: 2014

The structure of small gold nanoclusters (around 2.5 nm) deposited on different silica-on-silicon (SiOx/Si) substrates is investigated using several characterization techniques (AFM, XRD, EXAFS and GISAXS). The grain morphology and the surface roughness of the deposited gold cluster layers are determined by AFM. The in-plane GISAXS intensity is modelled in order to obtain information about the cluster size and the characteristic length scale of the surface roughness. The surface morphology of the deposited clusters depends on whether the native defect-rich (n-SiOx/Si) or the defect-poor substrate obtained by thermal treatment (t-SiO2/Si) is used. Gold clusters show a stronger tendency to aggregate when deposited on n-SiO x/Si, resulting in films characterized by a larger grain dimension (around 20 nm) and by a higher surface roughness (up to 5 nm). The more noticeable cluster aggregation on n-SiOx/Si substrates is explained in terms of metal-support interaction mediated by the defects located on the surface of the native silica substrate. Evidence of metal-support interaction is provided by EXAFS, demonstrating the existence of an Au-O distance for clusters deposited on n-SiOx/Si that is not found on t-SiO2/Si. © 2014 the Partner Organisations.


PubMed | Netherlands Organization for Scientific Research NWO, Rutherford Appleton Laboratory and University College London
Type: Journal Article | Journal: Journal of synchrotron radiation | Year: 2014

Energy-resolved electron-yield X-ray absorption spectroscopy is a promising technique for probing the near-surface structure of nanomaterials because of its ability to discriminate between the near-surface and bulk of materials. So far, the technique has only been used in model systems. Here, the local structural characterization of nanoporous cobalt-substituted aluminophosphates is reported and it is shown that the technique can be employed for the study of open-framework catalytically active systems. Evidence that the cobalt ions on the surface of the crystals react differently to those in the bulk is found.


PubMed | Netherlands Organization for Scientific Research NWO
Type: Journal Article | Journal: Physical chemistry chemical physics : PCCP | Year: 2014

The structure of small gold nanoclusters (around 2.5 nm) deposited on different silica-on-silicon (SiOx/Si) substrates is investigated using several characterization techniques (AFM, XRD, EXAFS and GISAXS). The grain morphology and the surface roughness of the deposited gold cluster layers are determined by AFM. The in-plane GISAXS intensity is modelled in order to obtain information about the cluster size and the characteristic length scale of the surface roughness. The surface morphology of the deposited clusters depends on whether the native defect-rich (n-SiOx/Si) or the defect-poor substrate obtained by thermal treatment (t-SiO2/Si) is used. Gold clusters show a stronger tendency to aggregate when deposited on n-SiOx/Si, resulting in films characterized by a larger grain dimension (around 20 nm) and by a higher surface roughness (up to 5 nm). The more noticeable cluster aggregation on n-SiOx/Si substrates is explained in terms of metal-support interaction mediated by the defects located on the surface of the native silica substrate. Evidence of metal-support interaction is provided by EXAFS, demonstrating the existence of an Au-O distance for clusters deposited on n-SiOx/Si that is not found on t-SiO2/Si.


PubMed | Ibaraki University, Netherlands Organization for Scientific Research NWO and Diamond Light Source
Type: Journal Article | Journal: IUCrJ | Year: 2014

Small- and wide-angle X-ray scattering (SAXS, WAXS) are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques, via either simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments.

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