Characterization of the high_c superconductor Y-Ba-Cu Oxide –critical current and crystal structure–

Critical currents are measured in the title material. At 9.5 K, where an apparent resistance is zero, the critical-current density _c is found to be about 1.7 A/cm² in a sintered sample. For currents smaller than _c the sample resistivity is less than 2.3 µΩ·cm. By X-ray diffraction the crystal structure is found to be essentially of a perovskite type. Its unit cell composed of eight units of the perovskite structure has a face-centered tetragonal symmetry with the lattice parameters =7.83±0.02 Å and =7.72±0.03 Å.