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Synthesis and characterization of the superconducting cuprates (Pb,Cu)Sr sub 2 (Y,Ca)Cu sub 2 O sub z

Journal Article · · Physical Review, B: Condensed Matter; (USA)
; ; ; ;  [1]
  1. Superconductivity Research Laboratory, ISTEC, 10-13, Shinonome 1-chome, Koto-ku, Tokyo 135, Japan (JP)

Single-phase ceramics of superconducting Pb-based layered copper oxides (Pb{sub (1+{ital x})/2}Cu{sub (1{minus}{ital x})/2})Sr{sub 2} (Y{sub 1{minus}{ital x}}Ca{sub {ital x}})Cu{sub 2}O{sub {ital z}} ({ital x}=0--0.35 and {ital z}{congruent}7) are successfully synthesized in an oxidizing atmosphere. The compounds that contain appropriate amounts of Ca ({ital x}{gt}0.2) exhibit superconductivity when annealed in air and subsequently quenched into liquid nitrogen. The superconductivity transition temperature increases with increasing {ital x} and is raised to 52 K for nearly single-phase samples with {ital x}=0.4. It is shown that, when the sample with {ital x}=0.35 is quenched, the oxygen content {ital z} decreases from 7.10 to 6.99, which is practically equal to the stoichiometric value of 7. It is shown that the length of the {ital a} axis is nearly independent of the value of {ital x}, being constant at a fixed value for each set of as-sintered and quenched samples and that the {ital a} axis of the crystal is shrunken by quenching compared with that of a crystal slowly cooled.

OSTI ID:
5692354
Journal Information:
Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:10; ISSN PRBMD; ISSN 0163-1829
Country of Publication:
United States
Language:
English