Correlation of the superconducting transition to oxygen stoichiometry in single-crystal Ba1−xKxBiO3−y
W. D. Mosley, J. W. Dykes, P. Klavins, R. N. Shelton, P. A. Sterne, R. H. Howell
DOI 10.1103/PhysRevB.48.611 · Physical Review B
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Abstract
Temperature-dependent positron-lifetime experiments have been performed from room temperature to 15 K on single crystals of the oxide superconductor Ba1−xKxBiO3−y. Results indicate that the filling of oxygen vacancies has a marked impact on the superconducting properties of this system. Cation defect concentrations were below the detectable limit of positron-annihilation-analysis techniques in this material, which is in sharp contrast to identical studies on polycrystalline samples. We find that the positron lifetime in these electrochemically deposited single crystals is determined by the oxygen stoichiometry of the lattice, but there is no experimental signature of strong positron localization. By performing a subsequent oxygen anneal on the crystals, the superconducting transition is sharpened and the onset is raised. The observed change in positron lifetime associated with this annealing procedure is in quantitative agreement with theory.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Ba1-xKxBiO3-y Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 32 | Pressure not reported | unknown |
| Ba1-xKxBiO3-y Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 30.8 | Pressure not reported | onset |
| Ba1-xKxBiO3-y Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 28 | Pressure not reported | onset |
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