Critical Current Densities and Irreversibility Fields of (B,C)(Sr,Ba) 2 Ca 2 Cu 3 O 9 and Ba 2 Ca 2 Cu 3 O 6 (O 2-y F y )

Critical current densities (Jc) and irreversibility fields (Hirr) have been estimated for (B,C)(Sr,Ba)2Ca2Cu3O9 (Tc=119K) and Ba2Ca2Cu3O6(O2.yFy) (Tc=109K) from magnetization measurements. The Jc and Hirr for (B,C)(Sr,Ba)2Ca2Cu3O9 have been considerably enhanced compared with the related materials of BSr2Ca2Cu3O9 and BSr2Ca3Cu4OII. It demonstrates that properties of the sample was strongly modified by the chemical control of Ba and/or carbon substitutions. On the other hand, 0223F system showed rather low Jc and Hirr in spite of the short spacing between CUO2 layers. 0223F system should be improved the Jc and Hirr performances by a chemical (a carrier doping) control.