Superconductor Science and Technology · 1989 · 42 citations · 7 references
Natural SciencesMaterials EngineeringMaterials ScienceInorganic ChemistryPhysical ChemistrySolid-state ChemistryElemental StoichiometryOxygen EffectStoichiometryAnnealingAnnealing Temperature EffectsCarrier ConcentrationOxygen Content AnalysisOxygen Partial Pressure EffectsOxygen StoichiometryOxygen Vacancies In Metal OxidesOxygen Vacancy Formation
The oxygen content of single-phase Bi2Sr2CaCu2O8+x depends on the annealing temperature and the oxygen partial pressure. The Tc maximum, 87 K, is associated with an excess oxygen content, x, of 0.035+or-0.003, as determined by volumetric analysis and thermogravimetry. This stoichiometry is obtained by, for instance, annealing in air at approximately 820 degrees C or in nitrogen at approximately 400 degrees C. For higher and lower x, Tc decreases. No structural changes associated with this change in oxygen content were observed; variations in Tc appear therefore to be associated with changes in carrier concentration. The rate of change of Tc with x is more than ten times greater than in YBa2Cu3Ox.
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High-Tc superconducting phases in the series Bi2.1(Ca, Sr)n+lCunO2n+4+δ
J.L. Tallon, R. G. Buckley, P.W. Gilberd et al. · Nature · 1988 · 290 citations
Transport and optical studies of single crystals of the 80-K Bi–Sr–Ca–Cu–O superconductor
H. Takagi, Hiroshi Eisaki, S. Uchida et al. · Nature · 1988 · 150 citations