Superconductivity above 90 K in Single Phase Y–Ba–Cu–O Compound

The results of x-ray diffraction, electrical resistance, DC and AC magnetization studies on two specimens of compositions Y 2.1 Ba 3.9 Cu 6 O 14 and Y 1.8 Ba 4.2 Cu 6 O 14 are presented. Our studies confirm that La 3 Ba 3 Cu 6 O 14 type ortnornombic phase is responsible for superconductivity in 90K range. The heat treatment that yields high quality samples with sharp transition in electrical resistance as well as in AC magnetic susceptibility measurements is described. Magnetic response just below T c is found to be sensitive to the measuring field.