Pb0.7Cu0.3Sr2Y0.5Ca 0.5Cu2Oy was synthesized as a mother specimen in air and then annealed under two different experimental conditions, in an oxidizing and in a reducing condition. The mother specimen was a nonsuperconductor, but both annealed specimens, one quenched from high temperature and the other treated in high-pressure O2, were superconductors with Tc's of about 50 K and about 60 K, respectively. The low Cu-valence of the quenched specimen which showed superconductivity suggests a decrease in the Pb-valence, while the high Tc of the specimen treated in high-pressure O2 would be explained by high Cu-valence and Pb4+.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering