Cu valence states in superconducting Bi-Pb-Sr-Ca-Cu-O system

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Journal of Solid State Chemistry; (USA)

DOI:https://doi.org/10.1016/0022-4596(90)90031-R· OSTI ID:6197365

Liu, H K; Dou, S X; Song, K H; Sorrell, C C ^[1]; Easterling, K E ^[2]; Jones, W K ^[3]

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1. Univ. of New South Wales, Kensington (Australia)
2. Lulea Univ. of Technology (Sweden)
3. State Univ. of Florida, Miami (USA)

The oxidation states of Bi, Pb, and Cu in the Bi-Pb-Sr-Ca-Cu-O (BPSCCO) system have been determined by a combination of volumetric measurement technique and iodometric titration. It was found that, in contrast to previous reports, the concentration of the Cu{sup 3+} ions decreased with increasing Pb content, and Cu{sup 3+} ions were absent in samples of Bi{sub 1.6}Pb{sub 0.4}Sr{sub 1.6}Ca{sub 2}Cu{sub 3}O{sub 9.8}, while a T{sub c} at 108 K and a J{sub c} of greater than 12,000 A/cm{sup 2} at 77 K were observed. The 110 K phase in BPSCCO was stabilized and showed a high tolerance to change in oxygen partial pressure during sintering. In Pb-doped materials, Bi appears to be trivalent while Pb was determined to be mixed-valence Pb{sup 4+}/Pb{sup 2+}. It is suggested that superconductivity in BPSCCO may result from a dynamic transfer of holes from Bi/Pb-O layers toward Cu-O{sub 2} planes.

• OSTI ID: 6197365
• Journal Information: Journal of Solid State Chemistry; (USA), Vol. 87:2; ISSN 0022-4596
• Country of Publication: United States
• Language: English

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36 MATERIALS SCIENCE
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VALENCE
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CUPRATES
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MEASURING METHODS
STRONTIUM
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