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Infiltration et croissance des céramiques YBa2Cu3O7-d texturées à structure perforée: relations microstructures et propriétés supraconductrices

Abstract : The superconducting oxide YBa2Cu3O7Δ (Y123), with its critical temperature of 92 K woke up with its discovery a great enthusiasm and continues to be the source of many works. Thanks to its good superconductive properties at the liquid nitrogen temperature (77 K) it seems to be very promising for the applications under magnetic field. In order to obtain higher critical current densities, it is necessary to increase their bulk density and to induce a preferential crystallographic orientation.
This work consisted of elaborating improved samples in term of superconducting properties. The conventional texture process induces cracks and porosities in the samples and requires addition of doping agents in order to improve materials properties. We have studied a new process named "infiltration and growth" as well as an original geometry "with thin walls". The characterizations carried out on this superconducting microstructures, concerning texture and properties are reported.
The optimization of the synthesis process consisted in understanding the mechanisms of infiltration and growth, then to seek the configuration and the composition giving of the most powerful samples. Critical currents densities close to 68 kA/cm2 under self field have been measured at 77 K.
The study of the perforated samples showed that, thanks to the artificial "holes", the microstructures are free of porosities and the samples cool more quickly. Concerning the oxygenation process of the samples this take place easier and its more homogeneous, compared to non-perforated pellets.
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Submitted on : Tuesday, January 30, 2007 - 10:36:00 AM
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  • HAL Id : tel-00126230, version 1

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Sophie Meslin. Infiltration et croissance des céramiques YBa2Cu3O7-d texturées à structure perforée: relations microstructures et propriétés supraconductrices. Matériaux. Université de Caen, 2006. Français. ⟨tel-00126230⟩

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