Calcium-substituted Y-Ba-Cu-O superconductors with enhanced Tc synthesized at elevated oxygen pressures
D. E. Morris, P. Narwankar, A. P. B. Sinha, K. Takano, B. Fayn, V. T. Shum
DOI 10.1103/PhysRevB.41.4118 · Physical Review B
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Abstract
Calcium substitution in the Y-Ba-Cu-O system at elevated P(O2) results in superconducting compounds with novel and enhanced properties: tetragonal CaxY(1−x)Ba2Cu3Oy with Tc=86 K for x=0.2 prepared at P(O2)=16 bars, and CaxY(1−x)Ba2Cu4Oy (1:2:4) with Tc=89 K for x=0.1 prepared at 50–200 bars. Calcium substitution shifts the phase-stability boundary between 1:2:3, 2:4:7, and 1:2:4 phases to higher P(O2), and stabilizes a tetragonal 1:2:3 structure at moderately elevated P(O2) without substantial decrease in Tc. The Tc of 1:2:4 increases with Ca substitution up to x=0.1, and then decreases gradually for larger x, possibly because of excessive hole concentration.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Ca0.2Y0.8Ba2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 86 | Pressure not reported | unknown |
| Ca0.1Y0.9Ba2Cu4Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 89 | Pressure not reported | unknown |
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