Valence states in Pb2Sr2Y1−xCaxCu3Oy

✍ Scribed by H.K. Liu; Y.L. Zhang; S.X. Dou

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 135 KB
• Volume: 185-189
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(91)92140-7

✦ Synopsis

The valence states of Cu and Pb in the PbzSr:Yt..Ca,Cu~O~, system have been investigated by the use of a combination of the volumetric measurement, iodometrie titration, and gravimetrie mea.~rements. It was found that the Cur'ions were absent in the entire regime from X = 0 to X = 1 and from pure oxygen treatment to pure nitrogen treatment. Mixed valent Pb~*/Pb z* exist in a wide range of composition and heat treatment conditions. The amount of Pb ~' increases with decreasing Y content for ~mples treated in the ~me oxygen partial pre~ure, and it reaches a maximum of 75% of Pb for a sample treated in pure oxygen at 45&C. Na doping promotes suFrconductivity.