Magnetization study of polycrystalline YBa 2Al xCu (3− x) O 7−δ ( x = 0.05, 0.10 and 0.20) compounds

Abstract

Superconductivity in polycrystalline YBa 2Al x Cu (3− x) O 7−δ materials was characterized by dynamic AC and quasistatic DC magnetometry. Intragranular persistent current density and low-loss intergranular critical current density were deduced using DC and AC techniques, respectively. Addition of aluminum produced modest increases in the intragranular persistent current for x < 0.2, but drastically reduced the intergranular 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.