References of "Cloots, Rudi"
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See detailRheological behavior of β-Ti and NiTi powders produced by atomization for SLM production of open porous orthopedic implants
Yablokova, G.; Speirs, M.; Van Humbeeck, J. et al

in Powder Technology (2015)

The growing interest for Selective Laser Melting (SLM) in orthopedic implant manufacturing is accompanied by the introduction of novel Ti alloys, in particular β-Ti for their excellent corrosion ... [more ▼]

The growing interest for Selective Laser Melting (SLM) in orthopedic implant manufacturing is accompanied by the introduction of novel Ti alloys, in particular β-Ti for their excellent corrosion resistance as well as favorable combination of high mechanical strength, fatigue resistance and relatively low elastic modulus. As part of the SLM process for producing quality β-Ti parts powder flowability is essential to achieve uniform thickness of powder layers. In this work the flowability of different gas atomized β-Ti, including NiTi, powders has been studied. Their rheological properties were compared to those of commercially available plasma-atomized Ti–6Al–4V powder using a newly developed semi-automatic experimental set-up. Not only the particle size, shape and size distribution of the powders display a large influence on the powder flowability but also particle surface properties such as roughness, chemical composition and the presence of liquid on the surface of the particles. It was found that plasma or gas atomization production techniques for SLM powder have a considerable effect on the particle topography. Among the powders studied regarding SLM applicability only rheological properties of the fine size fraction (25–45 μm) of Ti–45Nb didn't conform to SLM processing requirements. To improve flowability of the Ti–45Nb powder itwas annealed both in air and argon atmosphere at 600 °C during 1 h, resulting in an improved rheological behavior suitable for SLM processing. [less ▲]

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See detailTiO2 templated films used as photoelectrode for solid-state DSSC applications: Study of the solid electrolyte infiltration by Rutherford Backscattering Spectrometry
Dewalque, Jennifer ULg; Colson, Pierre ULg; Mathis, François et al

Poster (2015, May 10)

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials ... [more ▼]

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials. However, in solid-state dye-sensitized solar cells, optimal TiO2 films thickness is limited to a few microns allowing the adsorption of only a low quantity of photoactive dye and thus leading to poor light harvesting and low conversion efficiency. In order to overcome this limitation, high surface area templated films are investigated as alternative to nanocrystalline films prepared by doctor-blade or screen-printing. Moreover, templating is expected to improve the pore accessibility what would promote the solid electrolyte penetration inside the porous network, making possible efficient charge transfers. In this study, films prepared from different structuring agents are discussed in terms of microstructural properties (porosity, crystallinity) as well as effect on the dye loading and Spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)9,9'-spirobifluorene) solid electrolyte filling. Different techniques such as transmission electron microscopy (TEM), atmospheric poroellipsometry (AEP) and UV-visible absorption spectroscopy (UV-vis.) have been used to describe the microstructural features of the films. Besides, we have implemented Rutherford backscattering spectrometry (RBS) as an innovative non-destructive tool to characterize the hole transporting materials infiltration. Templated films show dye loading more than two times higher than nanocrystalline films prepared by doctor-blade or screen-printing and solid electrolyte infiltration up to 88%. [less ▲]

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See detailComparison of structural features of spin-coated and USP-deposited templated α-Fe2O3films
Toussaint, Caroline ULg; Chatzikyriakou, Daphne; Cloots, Rudi ULg et al

Poster (2015)

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See detailAtmospheric Pressure Plasma as an Activation Step for Improving Protein Adsorption on Hydroxyapatite Powder
Ozhukil Kollath, Vinayaraj ULg; Put, Sofie; Mullens, Steven et al

in Plasma Processes and Polymers (2015)

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See detailCombining mesoporosity and Ti-doping in hematite films for water splitting
Toussaint, Caroline ULg; Tran, Hoang Son ULg; Colson, Pierre ULg et al

in Journal of Physical Chemistry C (2015), 119(4), 1642-1650

(Graph Presented). In this study, we report the synthesis of Ti-doped mesoporous hematite films by soft-templating for application as photoanodes in the photoelectrolysis of water (water splitting ... [more ▼]

(Graph Presented). In this study, we report the synthesis of Ti-doped mesoporous hematite films by soft-templating for application as photoanodes in the photoelectrolysis of water (water splitting). Because the activation of the dopant requires a heat treatment at high temperature (≥800°C), it usually results in the collapse of the mesostructure. We have overcome this obstacle by using a temporary SiO2 scaffold to hinder crystallite growth and thereby maintain the mesoporosity. The beneficial effect of the activated dopant has been confirmed by comparing the photocurrent of doped and undoped films treated at different temperatures. The role of the mesostructure was investigated by comparing dense, collapsed, and mesoporous films heated at different temperatures and characterized under front and back illumination. It turns out that the preservation of the mesotructure enables a better penetration of the electrolyte into the film and therefore reduces the distance that the photogenerated holes have to travel to reach the electrolyte. As a result, we found that mesoporous films with dopant activation at 850°C perform better than comparable dense and collapsed films. [less ▲]

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See detailMagnetic shielding performances of YBa2Cu3O7−δ -coated silver tubes obtained by electrophoretic deposition
Devendra Kumar, N; Closset, Raphaël ULg; Wera, Laurent ULg et al

in Superconductor Science and Technology (2015), 28

We report a complete procedure to achieve multilayer YBCO thick films by electrophoretic deposition on silver tubes using a suspension of YBCO powder in butanol. With the aim to optimize the magnetic ... [more ▼]

We report a complete procedure to achieve multilayer YBCO thick films by electrophoretic deposition on silver tubes using a suspension of YBCO powder in butanol. With the aim to optimize the magnetic shielding performances of the coatings, we have carried out an extensive investigation of the influence of the deposition parameters, the multilayer deposition sequence and the intermediate/final heat treatments on the coating microstructure. Using the optimized conditions, a 24-layer YBCO coating has been successfully prepared on an 80 mm long Ag tube: the melt growth processed multilayered YBCO thick film thus obtained can shield an applied magnetic field of 1.9 mT at 77 K, the highest value per thickness unit reported so far in the literature for these materials. [less ▲]

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See detailElectrografting of polythiophenes on zinc oxide nanorods for photovoltaic cells
Demarteau, Jérémy ULg; Ouhib, Farid ULg; Henrist, Catherine ULg et al

Poster (2014, May 20)

As the rarefaction of fossil energies, photovoltaic cells are certainly amongst the most important energy sources for the future. Our work concentrated on hybrid photovoltaic cells that are based on ... [more ▼]

As the rarefaction of fossil energies, photovoltaic cells are certainly amongst the most important energy sources for the future. Our work concentrated on hybrid photovoltaic cells that are based on organic (polythiophene) and inorganic components (ZnO nanorods). The technology that maximizes the contact area between the two semi-conductor n and p while maintaining two separate components is the interdigital configuration. As the inorganic part, perfectly well aligned zinc oxide (ZnO) 1D nanostructures have been synthesized by hydrothermal growth on ZnO-seeded FTO substrates. SEM, AFM and XRD characterizations evidence patterned well- aligned nanorods with high c-axis, their roughness of surface and the length of their nanostructure. Concerning the organic component, we synthetize polythiophenes based diblock copolymer with high degree of regioregularity and predetermined molecular weight using Grignard Methatis (GRIM) process. Diblock polythiophene based copolymers are of interest because of the possibility of generating multifunctional materials (by associating the specific properties of each block), including their ability for self-assembly into well-defined nanostructures (fibrils or micelles) with controllable dimensions. Poly(3-hexylthiophene) (P3HT) composes the first block and the second block is either a polythiophene bearing an acrylate group on each monomer unit (PAcET), or a polythiophene bearing both acrylate and poly(ethylene glycol) side chains (P(AcET-co-PEGET)). Typically, the acrylates are used to fixe in a covalent way the copolymer to ZnO nanorods, while the PEG grafts are necessary for the solubilisation of the copolymer in the electrografting medium. 1H NMR and DLS characterizations allow us to find the backbone and the micellar structure of the copolymer. Cathodic polarization (electrografting) of ZnO nanorods induces electropolymerization of acrylate groups, leading to an adherent organized film of poly(thiophene)-based micelles. During the illumination tests, we obtained a typical response of a photovoltaic despite the low yields. This promising synthetic route opens exciting perspectives for the production and the electrochemical functionalization of different lengths of ZnO nanowires, which seems to be promising candidate for hybrids photovoltaic cells. [less ▲]

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See detailEffect of the RE (RE = Eu, Er) doping on the structural and textural properties of mesoporous TiO2 thin films obtained by evaporation induced self-assembly method
Borlaf, Mario; Caes, Sébastien ULg; Dewalque, Jennifer ULg et al

in Thin Solid Films (2014), 558

Polymeric sol–gel route has been used for the preparation of TiO2 and RE2O3–TiO2 (RE = Eu, Er) mesoporous thin films by evaporation induced self-assembly method using Si (100) as a substrate. The ... [more ▼]

Polymeric sol–gel route has been used for the preparation of TiO2 and RE2O3–TiO2 (RE = Eu, Er) mesoporous thin films by evaporation induced self-assembly method using Si (100) as a substrate. The influence of the relative humidity (RH) on the preparation of the film has been studied being necessary to work under 40% RH in order to obtain homogeneous and transparent thin films. The films were annealed at different temperatures until 900 °C/1 h and the anatase crystallization and its crystal size evolution were followed by low angle X-ray diffraction. Neither the anatase–rutile transition nor the formation of other compounds was observed in the studied temperature range. Ellipsoporosimetry studies demonstrated that the thickness of the thin films did not change after calcination at 500 °C, the porosity was constant until 700 °C, the pore size increased and the specific surface area decreased with temperature. Moreover, the effect of the doping with Er3 + and Eu3 + was studied and a clear inhibition of the crystal growth and the sintering process was detected (by transmission electron and atomic force microscopy) when the doped films are compared with the undoped ones. Finally, Eu3 + and Er3 + f–f transitions were detected by PL measurements. [less ▲]

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See detailInfluence of mesoporosity in hematite films on water splitting efficiency
Toussaint, Caroline ULg; Cloots, Rudi ULg; Henrist, Catherine ULg

Poster (2014)

Solar energy is inexhaustible but variable during the day and the seasons. Photoelectrolysis of water (water splitting) convert this energy into hydrogen to obtain an energy that can be stored and ... [more ▼]

Solar energy is inexhaustible but variable during the day and the seasons. Photoelectrolysis of water (water splitting) convert this energy into hydrogen to obtain an energy that can be stored and transported on demand. Hematite is a promising material for the photoanode in water splitting because of its high stability in water, cheapness, abundance and its band gap that enables the absorption of visible light (Eg: 2,1eV). Nevertheless, hematite has also some drawbacks including a short diffusion length of holes and a bad electronic conductivity. We have implemented spin coating and templating to produce doped mesoporous hematite films. The nanostructuration can improve the performances in water splitting by reducing the diffusion length of holes and increasing the specific surface between the film and the electrolyte. To suppress the collapse of the mesoporosity at high temperature (requested for dopant activation), we have used a temporary silica confinement scaffold that reduces the crystallite growth. To show the impact of the nanostructure, we have compared three films (mesoporous, collapsed and dense) in terms of hematite content (elemental analysis), nanostructure (electron microscopy), crystallinity (X-ray diffraction) and water splitting efficiency. We have also test two thermal treatments. This study highlights the effect of the effective interface with the electrolyte, through the preservation or not of open porosity and the different evolutions of the nanostructures as a function of the heat treatment. [less ▲]

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See detailMesoporous amorphous tungsten oxide electrochromic films: a Raman analysis of their good switching behavior
Chatzikyriakou, Dafni ULg; Krins, Natacha ULg; Gilbert, Bernard ULg et al

in Electrochimica Acta (2014), 137

The intercalation and de-intercalation of lithium cations in electrochromic tungsten oxide thin films are significantly influenced by their structural and surface characteristics. In this study, we ... [more ▼]

The intercalation and de-intercalation of lithium cations in electrochromic tungsten oxide thin films are significantly influenced by their structural and surface characteristics. In this study, we prepared two types of amorphous films via the sol-gel technique: one dense and one mesoporous in order to compare their response upon lithium intercalation and de-intercalation. According to chronoamperometric measurements, Li+ intercalates/de-intercalates faster in the mesoporous film (24s/6s) than in the dense film (48s/10s). The electrochemical measurements (cyclic voltammetry and chronoamperometry) also showed worse reversibility for the dense film compared to the mesoporous film, giving rise to important Li+ trapping and remaining coloration of the film. Raman analysis showed that the mesoporous film provides more accessible and various W-O surface bonds for Li+ intercalation. On the contrary, in the first electrochemical insertion and de-insertion in the dense film, Li+ selectively reacts with a few surface W-O bonds and preferentially intercalates into pre-existing crystallites to form stable irreversible LixWO3 bronze. [less ▲]

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See detailPore-filling of Spiro-OMeTAD determined by Rutherford backscattering spectrometry in templated TiO2 photoelectrodes
Dewalque, Jennifer ULg; Colson, Pierre ULg; Thalluri, Venkata Visveswara Gopala Kris ULg et al

in Organic Electronics (2014), 15

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials ... [more ▼]

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials. However, in solid-state dye-sensitized solar cells, optimal TiO2 films thickness is limited to a few microns allowing the adsorption of only a low quantity of photoactive dye and thus leading to poor light harvesting and low conversion efficiency. In order to overcome this limitation, high surface area templated films are investigated as alternative to nanocrystalline films prepared by doctor-blade or screen-printing. Moreover, templating is expected to improve the pore accessibility what would promote the solid electrolyte penetration inside the porous network, making possible efficient charge transfers. In this study, films prepared from different structuring agents are discussed in terms of microstructural properties (porosity, crystallinity) as well as impact on the dye loading and Spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)9,9'-spirobifluorene) solid electrolyte filling. We first report Rutherford backscattering spectrometry as an innovative non-destructive tool to characterize the hole transporting materials infiltration. Templated films show dye loading more than two times higher than nanocrystalline films prepared by doctor-blade or screen-printing and solid electrolyte infiltration up to 88%. [less ▲]

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See detailStudy of quasi-monophase Y-type hexaferrite Ba2Mg2Fe12O22 powder
Koutzarova, T.; Kolev, S.; Nedkov, I. et al

in Micro and Nanosystems (2014), 6(1), 14-20

We present the structural and magnetic properties of a multiferroic Ba2Mg2Fe12O22 hexaferrite composite containing a small amount of MgFe2O4. The composite material was obtained by auto-combustion ... [more ▼]

We present the structural and magnetic properties of a multiferroic Ba2Mg2Fe12O22 hexaferrite composite containing a small amount of MgFe2O4. The composite material was obtained by auto-combustion synthesis and, alternatively, by co-precipitation. The Ba2Mg2Fe12O22 particles obtained by co-precipitation have an almost perfect hexagonal shape in contrast with those prepared by auto-combustion. Two magnetic phase transitions, responsible for the composite’s multiferroic properties, were observed, namely, at 183 K and 40 K for the material produced by auto-combustion, and at 196 K and 30 K for the sample prepared by co-precipitation. No magnetic phase transitions in these temperature ranges were observed for a MgFe2O4 sample, which shows that the magnesium ferrite does not affect the multiferroic properties of this type of multiferroic metarials. [less ▲]

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See detailUltrasonic Spray Pyrolysis: an innovative fabrication method for electrochromic glazing
Maho, Anthony ULg; Domercq, Benoit; Denayer, Jessica et al

Conference (2014)

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See detailSurfactant-assisted ultrasonic spray pyrolysis of nickel oxide and lithium-doped nickel oxide thin films, towards electrochromic applications
Denayer, Jessica ULg; Bister, Geoffroy; Simonis, Priscilla et al

in Applied Surface Science (2014), 321

Lithium-doped nickel oxide and undoped nickel oxide thin films have been deposited on FTO/glass substrates by a surfactant-assisted ultrasonic spray pyrolysis. The addition of polyethylene glycol in the ... [more ▼]

Lithium-doped nickel oxide and undoped nickel oxide thin films have been deposited on FTO/glass substrates by a surfactant-assisted ultrasonic spray pyrolysis. The addition of polyethylene glycol in the sprayed solution has led to improved uniformity and reduced light scattering compared to films made without surfactant. Furthermore, the presence of lithium ions in NiO films has resulted in improved electrochromic performances (coloration contrast and efficiency), but with a slight decrease of the electrochromic switching kinetics. [less ▲]

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See detailImproved coloration contrast and electrochromic efficiency of tungsten oxide films thanks to a surfactant-assisted ultrasonic spray pyrolysis process
Denayer, Jessica ULg; Aubry, Philippe; Bister, Geoffroy et al

in Solar Energy Materials & Solar Cells (2014), 130

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See detailMineralogical and Physical Changes during Sintering of Plastic Red Clays from Sanaga Swampy Valley, Cameroon.
Nzeukou, Aubin; Traina, K.; Mjedo, E.R. et al

in International ceramique review (2014), 63(4), 186-192

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See detailSpray-drying synthesis of Na2FePO4F/carbon powders for lithium-ion batteries
Brisbois, Magali ULg; Krins, Natacha ULg; Hermann, Raphael et al

in Materials Letters (2014), 130

Sodium iron fluorophosphate Na2FePO4F is a candidate positive electrode material for both lithium-ion batteries and sodium-ion batteries. We report the synthesis of Na2FePO4F/carbon powders by the simple ... [more ▼]

Sodium iron fluorophosphate Na2FePO4F is a candidate positive electrode material for both lithium-ion batteries and sodium-ion batteries. We report the synthesis of Na2FePO4F/carbon powders by the simple and easily up-scalable technique of spray-drying. An aqueous solution containing citric acid as a carbon source was sprayed in a pilot-scale spray-dryer. Heat treatment at 600°C in argon for 12 hours was found appropriate to obtain single-phase Na2FePO4F; only 1.8% of Fe (III) were detected by iron-57 Mössbauer spectroscopy. When cycled against lithium, the discharge capacity reached 110 mAh g-1 at C/15 rate. (C) 2014 Elsevier B.V. All rights reserved. [less ▲]

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