References of "Rulmont, André"
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See detailBI-BASED 2223 SUPERCONDUCTING POLYCRYSTALLINE MATERIALS PREPARED BY EITHER A SOLID-STATE ROUTE OR A GLASSY MATRIX PRECURSOR METHOD - CHEMICAL-ANALYSIS AS WELL AS ELECTRICAL AND THERMAL TRANSPORT-PROPERTIES
Cloots, Rudi ULg; Bougrine, Hassan ULg; HOUSSA, M. et al

in Physica C (1994), 231(3-4), 259-270

Two routes have been followed in order to prepare Bi1.7Pb0.3Sr2Ca2Cu3O(y) superconducting materials. Bi1.7Pb0.3CuO4 is always used as one of the starting basic materials. The first route involves a new ... [more ▼]

Two routes have been followed in order to prepare Bi1.7Pb0.3Sr2Ca2Cu3O(y) superconducting materials. Bi1.7Pb0.3CuO4 is always used as one of the starting basic materials. The first route involves a new experimental procedure based on the solid state synthesis of separate intermediate phases, mixed together in a two (Bi1.7Pb0.3CuO4 + 2SrCaCuO3), three (Bi1.7Pb0.3CuO4+2SrCuO2+2CaCO3) or four (Bi1.7Pb0.3CuO4+(1/12)Sr8Ca6Cu24O41 + (3/2)CaCO3 + (4/3)SrCO3) powder process. Electric resistivity versus temperature measurements are presented. Even though the T(c)(0) of each sample is above 100 K, X-ray diffraction shows that the main phase is the 2212 phase in each case. Relatively pure 2223 materials have, however, successfully been produced by the second method, which starts from a glassy intermediate phase and involves a so-called 'matrix' method. The glass precursor phase is composed of one (Bi1.7Pb0.3CuO4), two (Bi1.7Pb0.3CuO4 + 2CaCO3), and three (Bi1.7Pb0.3CuO4 + (3/2)CaCO3 + (4/3)SrCO3) components as for the solid state routes. The role of both the added alkaline earth crystalline compounds and the glass matrix precursors in this second method turns out to be very important. We propose a schematic structural model in order to explain the selectivity of the starting materials. SrCaCuO3 is found to be a good precursor of the 2212 phase, while SrCuO2 gives rise to the 2223 phase. It seems that the presence of CaCO3 in the glassy intermediate phase, thus acting as a cation reservoir, is very useful for the production of the 2223 phase. Electric resistivity, thermal conductivity and thermopower versus temperature measurements are also presented and discussed in terms of intergrowths and variations of cationic compositions in the Bi-based layers. [less ▲]

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See detailSTUDY OF THE CRYSTALLIZATION PROCESS IN BI2-XPBXSR2CA2CU3O10-Y GLASS SYSTEMS - OPTICAL POLARIZED-LIGHT MICROSCOPY, ELECTRICAL AND MAGNETIC-PROPERTIES
Cloots, Rudi ULg; Romain, Anne-Claude ULg; Rulmont, André ULg et al

in Superconductor Science & Technology (1993), 6(12), 850-857

Synthesis of Bi2-xPbxSr2Ca2Cu3O10-y (x = 0 and x = 0.3) has been performed using the glass recrystallization route technique. After splat quenching, the samples were annealed at 820, 850 or 870-degrees-C ... [more ▼]

Synthesis of Bi2-xPbxSr2Ca2Cu3O10-y (x = 0 and x = 0.3) has been performed using the glass recrystallization route technique. After splat quenching, the samples were annealed at 820, 850 or 870-degrees-C for 96 or 144 h (with one intermediary grinding). High-resolution polarization micrographs and electrical (and magnetic susceptibility) measurements have been taken. Various growth mechanisms can thus be checked, and the physical properties are studied in relation to the microstructure. It is found that the 2223 phase does not crystallize directly from the amorphous one but results from a dissolution-reprecipitation process. The stability of the 2212 phase is emphasized. The 2201 phase precipitates at high temperature and rapidly reacts with the melt to form the 2223 phase. The kinetics of the lead-substituted sample seems to be controlled by the Ca2PbO4 phase. which acts as a flux. [less ▲]

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See detailSuperconductivity in YBa1.95Cs0.05Cu3O7-y granular ceramics
Ausloos, Marcel ULg; Laurent, Christian; Vanderschueren, Hyacinthe ULg et al

in Physical Review B (1989), 39(4), 2729-2732

A new compound of the high-temperature ceramic oxide superconductor family has been synthesized and analyzed, i.e., YBa1.95Cs0.05Cu3O7-y. Its crystallographic structure is given. Two well-defined ... [more ▼]

A new compound of the high-temperature ceramic oxide superconductor family has been synthesized and analyzed, i.e., YBa1.95Cs0.05Cu3O7-y. Its crystallographic structure is given. Two well-defined "critical regimes" are observed at 86 and 90 K, respectively, on electrical resistivity measurements. Magnetoresistivity measurements are also reported for small magnetic field. No anomalous hysteresis is found. Features in these transport properties are interpreted in terms of phase mixtures. The interest of such data is emphasized. [less ▲]

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