Synthesis of the CuSr2YCu2O7 compounds with Re, W and Mo substituted for Cu has been optimized for the highest Tc. Materials prepared in air at 990°C and annealed at 650-700°C in 220 atm. O2 are tetragonal with the transition elements substituting on the Cu-"chain" site, have oxygen content ∼ 7.3, and are superconducting with Tc ∼ 70 K. The irreversibility lines show rather poor pinning characteristics when compared to Y123. Superconducting Tc values were increased up to 77 K by additional substitution of small amounts of Ca for Y. Based on a.c. susceptibility and d.c. magnetization measurements, Ca substitution improves superconducting properties making chemically stabilized CuSr2YCu2O7 materials interesting for high field applications below 30 K.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering