Аннотация:Magnetization measurements have been performed for the newly found superconductor, BiSrCaCu 2 O x , which is composed of two phases, i.e., a high- T c phase (105 K) and a low- T c phase (75 K). The superconductor is found to be of type II and the lower critical field of the high- T c phase is as small as 16.2 Oe at 77 K. The volume fraction of the high- T c phase is as high as 21% in the present sample. The hysteresis observed in the magnetization vs field curve is much smaller in BiSrCaCu 2 O x than in YBa 2 Cu 3 O y , implying a small critical current density in the high- T c phase.
