Bi2Sr2CaCu2O8+δ (Bi-2212) is a high temperature superconducting compound whose critical temperature Tc is deeply affected by the amount δ of non-stoichiometric oxygen, which also induces remarkable changes in the resistivity vs. temperature behaviours ρ(T). Recent studies have shown that important ionic migration phenomena occur in high quality Bi-2212 whisker- crystals even at room temperature. Although the influence of the environmental atmosphere on the ρ(T) characteristics strongly suggests that such phenomena imply an oxygen depletion in the crystal. In order to evaluate ageing effects in Bi-2212 whiskers, we have carried out Backscattering Spectroscopy (BS) experiments at the microbeam facility of the National Laboratory of Legnaro within the ALCHIMIA project. Since the measurements were carried out in high vacuum conditions, the samples were mounted on a cryostat and the measurements were carried out at about 80 K, in order to avoid O desorption during the measurements. To test the sensitivity of our experiment to monitor the evolution of the Bi-2212 stoichiometry, preliminary measurements were carried out on samples before and after annealing in vacuum conditions.
Evolution of oxygen content in Bi-2212 superconducting whiskers by Micro-BS measurementsin LNL Annual Report
COLOMBO, Elisabetta;AGOSTINO, Angelo;CAGLIERO, Stefano;LO GIUDICE, Alessandro;MANFREDOTTI, Claudio;TRUCCATO, Marco;VISCA, Lorenzo;VITTONE, Ettore
2007-01-01
Abstract
Bi2Sr2CaCu2O8+δ (Bi-2212) is a high temperature superconducting compound whose critical temperature Tc is deeply affected by the amount δ of non-stoichiometric oxygen, which also induces remarkable changes in the resistivity vs. temperature behaviours ρ(T). Recent studies have shown that important ionic migration phenomena occur in high quality Bi-2212 whisker- crystals even at room temperature. Although the influence of the environmental atmosphere on the ρ(T) characteristics strongly suggests that such phenomena imply an oxygen depletion in the crystal. In order to evaluate ageing effects in Bi-2212 whiskers, we have carried out Backscattering Spectroscopy (BS) experiments at the microbeam facility of the National Laboratory of Legnaro within the ALCHIMIA project. Since the measurements were carried out in high vacuum conditions, the samples were mounted on a cryostat and the measurements were carried out at about 80 K, in order to avoid O desorption during the measurements. To test the sensitivity of our experiment to monitor the evolution of the Bi-2212 stoichiometry, preliminary measurements were carried out on samples before and after annealing in vacuum conditions.
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