MAGNETIZATION STUDY OF POLYCRYSTALLINE YBA2ALXCU(3-X)O-7-DELTA (X=0.05, 0.10 AND 0.20) COMPOUNDS

Superconductivity in polycrystalline YBa2AlxCu(3-x)O-7-delta materials was characterized by dynamic AC and quasistatic DC magnetometry. Intr agranular persistent current density and low-loss intergranular critic al current density were deduced using DC and AC techniques, respective ly. Addition of aluminum produced modest increases in the intragranula r persistent current for x < 0.2, but drastically reduced the intergra nular critical current density for x = 0.2. The critical temperature T -c for superconductivity decreased only 4% for Al content up to x = 0. 2.