Superconductivity Studies on the High Tc Phase in the Y–Ba–Cu–O System

Synthesis, characterization and superconducting behavior of the phases (i) Y 2-x Ba x Cu 2 O 5 (0\leqslantx\leqslant1.6) and (ii) YBa 2 Cu 3+x O 7+y (0\leqslantx\leqslant2.0) are reported. The composition YBa 2 Cu 4 O 7+y shows a T c (zero resistance) of 94K.