References of "Rulmont, André"
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See detailPreparation of nanosized barium zirconate powder by thermal decomposition of urea in an aqueous solution containing barium and zirconium, and by calcination of the precipitate
Boschini, Frédéric ULg; Robertz, B.; Rulmont, André ULg et al

in Journal of the European Ceramic Society (2003), 23(16), 3035-3042

The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio ... [more ▼]

The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate. A calcination at 1200 degreesC during 2 h gives rise to the formation of a pure barium zirconate phase. Microstructural characterisations have been performed in order to evaluate the sintering behaviour. Dilatometric measurements, coupled with scanning electron microscopy analyses clearly indicate that barium carbonate decomposition process leads to the formation of internal porosity which severely limits the density of the material, even if a sintering was performed at 1500 degreesC. A careful control of the heating profile seems to be necessary in order to produce dense materials. (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

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See detailSynthesis of CMR manganate compounds: the consequences of the choice of a precursor method
Vertruyen, Bénédicte ULg; Rulmont, André ULg; Cloots, Rudi ULg et al

in Materials Letters (2002), 57(3), 598-603

We have studied the electrical transport properties of manganate samples synthesized by different precursor methods. Differences in the synthesis process of the materials can result in samples with ... [more ▼]

We have studied the electrical transport properties of manganate samples synthesized by different precursor methods. Differences in the synthesis process of the materials can result in samples with similar grain size but very different physical properties, contrary to what happens in samples prepared by the same method. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailControlled ring-opening polymerization of epsilon-caprolactone in the presence of layered silicates and formation of nanocomposites
Kubies, Dana; Pantoustier, Nadège; Dubois, Philippe et al

in Macromolecules (2002), 35

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See detailYBa2Cu3O7 tapes prepared by sol-gel deposition techniques: microstructure and structural characterizations
Marguillier, David ULg; Cloots, Rudi ULg; Rulmont, André ULg et al

in Physica C: Superconductivity (2002), 372(Part 2), 715-718

We report on the preparation conditions of YBa2Cu3O7 polycrystalline superconducting tapes by a sol-gel deposition technique. We present some discussion on the compatibility between the nature of the ... [more ▼]

We report on the preparation conditions of YBa2Cu3O7 polycrystalline superconducting tapes by a sol-gel deposition technique. We present some discussion on the compatibility between the nature of the substrate, the use of a buffer layer, and the conditions used to prepare appropriate superconducting YBa2Cu3O7,, materials. We report also on the microstructural characterizations performed in order to evaluate the crystallites size, degree of orientation and connectivity. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailCu doping as a tool for understanding CMR
Vertruyen, Bénédicte ULg; Cloots, Rudi ULg; Rulmont, André ULg et al

in Key Engineering Materials [=KEM] (2002), 206-2

Doping at the Mn-site in CMR manganate-based perovskites has been shown to affect strongly the physical properties of those compounds. We study here the effect of copper substitution in the low doping ... [more ▼]

Doping at the Mn-site in CMR manganate-based perovskites has been shown to affect strongly the physical properties of those compounds. We study here the effect of copper substitution in the low doping range on the electrical transport properties of La0.7Ca0.3MnO3. It turns out that the transition temperature decrease observed in doped samples can be drastically reduced by addition of silicon dioxide SiO2. It is shown that copper is trapped in a secondary phase composed of La,Ca,Si,Cu and O. The resultant Mn-site vacancies appear to be less detrimental to the electronic conduction than the likely antiferromagnetic clusters induced by the copper ions in the Mn-O network. [less ▲]

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See detailImportance of soft solution processing for advanced BaZrO3 materials
Robertz, B.; Boschini, Frédéric ULg; Cloots, Rudi ULg et al

in International Journal of Inorganic Materials (2001), 3(8), 1185-1187

Barium zirconate is an interesting material for refractory applications as well as a good substrate for the manufacturing of high temperature superconductors. However, its solid state synthesis requires ... [more ▼]

Barium zirconate is an interesting material for refractory applications as well as a good substrate for the manufacturing of high temperature superconductors. However, its solid state synthesis requires high temperature and provides inhomogeneous powder with a broad particle size distribution. In order to avoid these disadvantages, soft solution routes are of growing importance in the ceramic powder synthesis. Precipitation. decomposition of precursors, combustion techniques offer alternative ways to the solid state method. Advantages of these are a lower calcination temperature, production of homogeneous and fine monodisperse powders. The obtained powders have been characterised by XRD, IR, SEM and DTA/TG analysis. The influence of the synthesis conditions on the properties of BaZrO3 has been studied. (C) 2001 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailPreparation and properties of layered silicate nanocomposites based on ethylene vinyl acetate copolymers
Alexandre, Michaël ULg; Beyer, Günter; Henrist, Catherine ULg et al

in Macromolecular Rapid Communications (2001), 22(8), 643-646

(Nano)composites based on ethylene vinyl acetate copolymers (EVA) and montmorillonite modified by various alkylammonium cations were processed by mechanical kneading. Polymer intercalation and filler ... [more ▼]

(Nano)composites based on ethylene vinyl acetate copolymers (EVA) and montmorillonite modified by various alkylammonium cations were processed by mechanical kneading. Polymer intercalation and filler exfoliation were evidenced by X-ray diffraction and transmission electron microscopy, respectively. Nano-composites tensile properties showed that Young's modulus increases significantly even at very low content of the organo-modified filler while preserving high ultimate elongation and tensile stress. The matrix thermal stability in air was increased by 40°C and, interestingly, the obtained nanocomposites present flame retardant properties. TEM micrograph of the nanocomposite based on EVA3 filled with 5 wt.-% of Mont-2CN2C18. [less ▲]

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See detailMagnetotransport properties of a single grain boundary in a bulk La-Ca-Mn-O material
Vertruyen, Bénédicte ULg; Cloots, Rudi ULg; Rulmont, André ULg et al

in Journal of Applied Physics (2001), 90(11), 5692-5697

Besides the "intrinsic" colossal magnetoresistance effect observed in single crystals, the polycrystalline manganate compounds also exhibit an "extrinsic" magnetoresistance related to the presence of ... [more ▼]

Besides the "intrinsic" colossal magnetoresistance effect observed in single crystals, the polycrystalline manganate compounds also exhibit an "extrinsic" magnetoresistance related to the presence of grain boundaries. We report electrical transport and magnetic measurements carried out on a bigrain sample extracted from a floating zone method-grown rod of calcium doped lanthanum manganate. Electrical resistance was measured both within a grain and across the grain boundary, between 20 and 300 K and from 0 to 8 T. Magnetoresistance values up to 99% are reached within the grain. The temperature dependence of the resistance across the grain boundary displays a "foot-like" feature towards the bottom of the transition. Low field and high field magnetoresistance effects are examined. We compare our results for a "bulk" grain boundary to those obtained by other authors for bicrystal thin films and bulk polycrystalline materials. (C) 2001 American Institute of Physics. [less ▲]

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See detailPoly(e-caprolactone) layered silicate nanocomposites: effect of clay surface modifiers on the melt intercalation process
Pantoustier, Nadège; Alexandre, Michaël ULg; Degée, Philippe et al

in e-Polymers (2001), (9), 1-9

Nanocomposites based on biodegradable poly(e-caprolactone) (PCL) and layered silicates (montmorillonite) modified by various alkylammonium cations were prepared by melt intercalation. Depending on whether ... [more ▼]

Nanocomposites based on biodegradable poly(e-caprolactone) (PCL) and layered silicates (montmorillonite) modified by various alkylammonium cations were prepared by melt intercalation. Depending on whether the ammonium cations contain non-functional alkyl chains or chains terminated by carboxylic acid or hydroxyl functions, microcomposites or nanocomposites were recovered as shown by X-ray diffraction and transmission electron microscopy. Mechanical and thermal properties were examined by tensile testing and thermogravimetric analysis. The layered silicate PCL nanocomposites exhibited some improvement of the mechanical properties (higher Young's modulus) and increased thermal stability as well as enhanced flame retardant characteristics as result of a charring effect. This communication aims at reporting that the formation of PCL-based nanocomposites strictly depends on the nature of the ammonium cation and its functionality, but also on the selected synthetic route, i.e. melt intercalation vs. in situ intercalative polymerization. Typically, protonated w-aminododecanoic acid exchanged montmorillonite allowed to intercalate e-caprolactone monomer and yielded nanocomposites upon in situ polymerization, whereas they exclusively formed microcomposites when blended with preformed PCL chains. In other words, it is shown that the formation of polymer layered silicate nanocomposites is not straightforward and cannot be predicted since it strongly depends on parameters such as ammonium cation type and functionality together with the production procedure, i.e., melt intercalation, solvent evaporation or in situ polymerization [less ▲]

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See detailTwo peak effect in GMR : a chemical effect ?
Vertruyen, Bénédicte ULg; Rulmont, André ULg; Dorbolo, Stéphane ULg et al

in Materials Research Society Symposium Proceedings (2000), 602

We show that the synthesis conditions have a dramatic influence on the resistivity behavior of calcium and sodium doped LaMnO3. Several samples prepared by lowtemperature techniques exhibit a double ... [more ▼]

We show that the synthesis conditions have a dramatic influence on the resistivity behavior of calcium and sodium doped LaMnO3. Several samples prepared by lowtemperature techniques exhibit a double-peaked curve of resistance versus temperature. The model of spin-polarized intergranular tunneling provides a good approach to discuss our experimental results. Grain size and crystallinity are proved to be essential parameters, which are strongly influenced by the preparation process (e.g. the precursors nature and the thermal treatment). [less ▲]

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See detailAnomalous temperature behavior of the resistivity in lightly doped manganites around a metal-insulator phase transition
Sergeenkov, S.; Ausloos, Marcel ULg; Bougrine, Hassan ULg et al

in JETP Letters (1999), 70(7), 481-487

An unusual temperature and concentration behavior of the resistivity ρ(T,x) in La0.7Ca0.3Mn1-xCuxO3 is observed at slight Cu doping (0 ≤x≤ 0.05). Namely, the introduction of copper results in a splitting ... [more ▼]

An unusual temperature and concentration behavior of the resistivity ρ(T,x) in La0.7Ca0.3Mn1-xCuxO3 is observed at slight Cu doping (0 ≤x≤ 0.05). Namely, the introduction of copper results in a splitting of the resistivity maximum around the metal-insulator transition temperature T0(x) into two differently evolving peaks. Unlike the original Cufree maximum, which steadily increases with doping, the second (satellite) peak remains virtually unchanged for x<xc, increases for x≥xc, and finally disappears at xm ≃ 2xc, with xc ≃ 0.03. The observed phenomenon is thought to arise from a competition between substitution-induced strengthening of the potential barriers (which hinder the charge hopping between neighboring Mn sites) and weakening of the kinetic energy of the carriers. The data are well fitted by assuming a nonthermal tunneling conductivity theory with randomly distributed hopping sites. © 1999 American Institute of Physics. [less ▲]

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See detailEffect of BaZrO3 additions on the microstructure and physical properties of melt-textured Y-123 superconducting materials
Cloots, Rudi ULg; Robertz, B.; Auguste, F. et al

in Materials Science & Engineering : B (1998), 53(1-2), 154-158

The effect of BaZrO3 additions on the microstructure and physical properties of melt-textured Y-123 have been investigated. The distribution of the 211 particles is strongly modified by the presence of ... [more ▼]

The effect of BaZrO3 additions on the microstructure and physical properties of melt-textured Y-123 have been investigated. The distribution of the 211 particles is strongly modified by the presence of such an additive. In fact, BaZrO3 is effective in reducing the size of the 211 particles. As a consequence, a strong interaction in terms of repulsion takes place between the 123 growth front and the 211 particles which are partially dissolved in the reactive liquid phase. New types of patterns are also reported in the microstructure of such materials and are related to the presence of BaZrO3 in the melt. [less ▲]

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See detailThe Nd-123 superconducting system: From single crystal to top-seeded large grain. Physical and chemical parameters influence
Auguste, F.; Vandewalle, Nicolas ULg; Ausloos, Marcel ULg et al

in Applied Superconductivity (1998), 6(2-5), 77-85

Nd-123 signle crystals have been produced via the Aux method in alumina crucibles by controlling the chemical composition of the flux. For so doing, quenched materials have been prepared and analyzed in ... [more ▼]

Nd-123 signle crystals have been produced via the Aux method in alumina crucibles by controlling the chemical composition of the flux. For so doing, quenched materials have been prepared and analyzed in order to get information about the optimum barium: copper ratio for an unchanged neodymium concentration. Non corrosive fluxes with a low viscosity have been put into evidence and can thus be used for single crystal production. Experiments have been performed with three different chemical compositions of the Aux and by considering various amounts of neodymium oxide for each system. The single crystals have been analyzed by energy dispersive X-ray microanalysis and used for the synthesis of large Dy-123 single-domains? [less ▲]

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See detailDirectional solidification by appropriate chemically active single crystal seed: An alternative way of generating large superconducting 123 single domain
Cloots, Rudi ULg; Auguste, F. X.; Rulmont, André ULg et al

in Journal of Materials Research (1997), 12(12), 3199-3202

A Dy2O3 single crystal has been used as a seed for the growth of isothermally melt-textured DY-123 material. The nucleation-controlled step has been observed to be related to the heterogeneous nucleation ... [more ▼]

A Dy2O3 single crystal has been used as a seed for the growth of isothermally melt-textured DY-123 material. The nucleation-controlled step has been observed to be related to the heterogeneous nucleation of 211 particles at the surface of the dysprosium oxide single crystal. The subsequent growth mode seems to be controlled by a high concentration gradient of dysprosium in the liquid phase. This leads to a directional solidification process of the 123 phase. The size of the 211 particles seems to decrease as the distance from the dysprosium oxide single crystal increases. [less ▲]

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See detailMicrostructure development in isothermally melt-textured 123-211 composite materials
Auguste, F.; Rulmont, André ULg; Vandewalle, Nicolas ULg et al

in Journal of Low Temperature Physics (1996), 105(5-6), 1439-1444

Microstructures of isothermally melt-textured 123-211 composite materials have been examined during the solidification process from quenched specimens. The distribution of 211 particles, the ... [more ▼]

Microstructures of isothermally melt-textured 123-211 composite materials have been examined during the solidification process from quenched specimens. The distribution of 211 particles, the superconducting 123 grain boundary and the solid-liquid interface features are emphasized. The quality of the materials has been investigated by thermopower and thermal conductivity measurements. A seeded-melt texturing technique has been also tested in order to grow large single-domain of DyBa2Cu3O7-y. The chosen seed was a Dy2O3 single crystal. [less ▲]

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See detailField percolation and high current density in 80/20 DyBa2Cu3O7-x/Dy2BaCuO5 bulk magnetically textured composite ceramics
Cloots, Rudi ULg; Dang, An; Vanderbemden, Philippe ULg et al

in Zeitschrift Fur Physik B-Condensed Matter (1996), 100(4), 551-555

We measured the AC susceptibility of magnetically textured (123) 80%/211(20%) DyBaCuO composite in a special set-up in order to enhance the intergrain contribution. The synthesis process led to very clean ... [more ▼]

We measured the AC susceptibility of magnetically textured (123) 80%/211(20%) DyBaCuO composite in a special set-up in order to enhance the intergrain contribution. The synthesis process led to very clean ''weak links'' at grain boundaries. At the percolation threshold bulk shielding paths were such that the intergrain critical current density J(c) was above 10(5) A/cm(2). The field dependence of J(c) was understood through an analytical form indicating a distribution of currents similar to the law of clusters at fracture/percolation thresholds. [less ▲]

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See detailMagnetic alignment in 2212 Bi-based superconducting system .1. Magnetic orientation of Bi2Sr2Ca1-x(RE)(x)Cu2O8-y [(RE)=Gd, Dy, Ho, Er] powder dispersed in epoxy resin at room temperature
Stassen, S.; Cloots, Rudi ULg; Vanderbemden, Philippe ULg et al

in Journal of Materials Research (1996), 11(5), 1082-1085

The magnetic anisotropy of rare-earth substituted 2212 materials (Bi(2)Sr(2)Ca(0.8)RE(0.2)Cu(2)O(x) with RE = Gd, Dy, Ho, Er) is put into evidence. Superconducting powder dispersed in epoxy resin is ... [more ▼]

The magnetic anisotropy of rare-earth substituted 2212 materials (Bi(2)Sr(2)Ca(0.8)RE(0.2)Cu(2)O(x) with RE = Gd, Dy, Ho, Er) is put into evidence. Superconducting powder dispersed in epoxy resin is oriented under an external magnetic field (4 T) in a direction that depends on the nature of the rare-earth used in the substitution. Both directions of observation (parallel or perpendicular to the field) were investigated. Splitting of (00l) peaks is neatly observed and discussed. [less ▲]

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See detailMagnetic texturing of bulk samples of the superconductor Bi2Sr2Ca0.8Dy0.2Cu2O8-y
Stassen, Sophie; Rulmont, André ULg; Vanderbemden, Philippe ULg et al

in Journal of Applied Physics (1996), 79(1), 553-555

The texturing process of Bi-Sr-Ca(Dy)-Cu-O (2212) is optimized by sintering under a magnetic field. The precursor crystalline powder is melted and grown under a 1.2 T magnetic field. Textured samples are ... [more ▼]

The texturing process of Bi-Sr-Ca(Dy)-Cu-O (2212) is optimized by sintering under a magnetic field. The precursor crystalline powder is melted and grown under a 1.2 T magnetic field. Textured samples are characterized by x-ray diffraction, scanning electron microscopy, electrical resistivity, and magnetic susceptibility. (C) 1996 American Institute of Physics. [less ▲]

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See detailCrystallization of vitreous high-T-c superconducting oxide through laser zone melting method.
Ausloos, Marcel ULg; Bougrine, Hassan ULg; Cloots, Rudi ULg et al

in Institute of Physics Conference Series (1995), 148

We synthesized Bi2Sr2CaCu2O8-y ceramics through the vitreous route. After insertion in epoxy resin, we exposed the materials to a CO2 laser beam. Various intensities and sweeping conditions were examined ... [more ▼]

We synthesized Bi2Sr2CaCu2O8-y ceramics through the vitreous route. After insertion in epoxy resin, we exposed the materials to a CO2 laser beam. Various intensities and sweeping conditions were examined. We observed the samples in high resolution polarized light microscopy and with electron scanning microscopy. Crystallization zones could be detected. A systematic analysis gave the correlation between the behavior of the material and its synthesis conditions. Electrical properties were measured through micro-electrode deposited on the surface at various locations. No superconductivity was found. The optimization of such a process and potential applications will be discussed. [less ▲]

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