Oxygen concentration effect on T/sub c/ of the Bi-Ca-Sr-Cu-O superconductor

Journal Article · Sat Apr 01 00:00:00 EST 1989 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.39.6612· OSTI ID:6407799

Morris, D E; Hultgren, C T; Markelz, A M; Wei, J Y.T.; Asmar, N G; Nickel, J H

The T/sub c/ of Bi/sub 2/-Ca-Sr/sub 2/-Cu/sub 2/-O/sub 8-//sub x/ can be shifted reversibly over a rangel of at least 15 K by changing the oxygen concentration. T/sub c/ shifts downward for increased oxygen content. This is opposite to the shift seen in YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ and may be caused by reduction in the Fermi level reducing conductivity in the Bi-O layers. Oxygen concentration is varied by treatment in O/sub 2/ at appropriate pressures. The highest T/sub c/ = 78.5 K of the ''80-K'' phase is obtained by treating at 600 /sup 0/C in 10/sup -2/-bar oxygen. T/sub c/ shifts down to 65.4 K after treatment at 137 bars. The transitions remain sharp, with no evidence of significant structural change by x-ray powder diffraction. The original T/sub c/ is restored upon retreatment in O/sub 2/ at low partial pressure. The 110-K phase showed a much smaller shift (..delta..T/sub c/approx. =4 K) after treatment in O/sub 2/ at 134 bar.

• Research Organization: Physics Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• OSTI ID: 6407799
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 39:10
• Country of Publication: United States
• Language: English

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