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Optimisation des propriétés anisotropes d'échantillons massifs supraconducteurs Bi2223 texturés par frittage-forgeage

Abstract : The high-Tc superconducting (Bi,Pb)2Sr2Ca2Cu3O10+x (Bi2223) oxide has been synthesised by a sol-gel route. The calcination and sintering conditions have been optimized in order to synthesise a nearly pure Bi2223 phase, around 94%. The resulting powder has been sinter-forged under air into highly textured discs by optimising the processing conditions. Bars cut from these discs exhibit reproducible transport critical current densities (Jc) having values around 10000 A/cm2 (0 T, 77 K) which are similar to the maximum ones present in the literature. A new way of synthesis, consisting in texturing pellets composed of the Bi2212 phase and secondary phases, was undertaken. The control of the particles size (⊕<63µm) and of the sinter-forging parameters (845°C/100h) allowed to attain Jc around 12500 A/cm2. Ball milling of the sol-gel powder is crucial for increasing its reactivity and in the same time the ratio of Bi2223 phase after sintering-forging. The great quantity of liquid phase produced during texturation allowed the improvement of texture quality via a better alignment of the grains and thus led to strongly increase the critical current densities (20000 A/cm2). In addition, the stacking of several discs was not only shown to be a possible and fast process, but also to produce a massive ceramic with critical current densities almost identical to that obtained on only one disc. The combined analysis (texture/structure/microstructure) treated via the program MAUD presents a great effectiveness to characterize our samples. Thanks to neutron diffraction, a direct relation between the Bi2223 phase content, the cell parameters, the crystallites size , the density of maximum distribution and the transport critical current density was established.
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https://tel.archives-ouvertes.fr/tel-00009361
Contributor : Emmanuel Guilmeau <>
Submitted on : Wednesday, June 1, 2005 - 10:04:27 AM
Last modification on : Wednesday, November 25, 2020 - 9:30:04 AM
Long-term archiving on: : Monday, September 17, 2012 - 3:45:25 PM

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  • HAL Id : tel-00009361, version 1

Citation

Emmanuel Guilmeau. Optimisation des propriétés anisotropes d'échantillons massifs supraconducteurs Bi2223 texturés par frittage-forgeage. Matériaux. Université de Caen, 2003. Français. ⟨tel-00009361⟩

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