The irreversibility line and Curie-Weiss temperature of the superconductor LaCaBaCu_3-X(BO₃)_Xwith x= 0.2 and 0.3

LaCaBaCu₃O₇ is a high critical temperature superconductor (HTS) below the T_c = 80 K and its structure is similar to that of YBCO. In this work we study the effect in the irreversibility line and the Curie-Weiss temperature of this superconductor after borate (BO₃)^3- doping (LaCaBaCu_3-x(BO₃)_xO_7-δx=0.2 and 0.3). Interestingly, borate doping enhances the irreversibility line and this effect is probably caused from alteration the arrangement of the oxygen atoms in the crystalline structure. Moreover, the Curie-Weiss temperature (□_p) in the normal state increases with doping concentration. Calculated □_p for pure LaCaBaCu₃O₇ is around -98K, this value increases to -75 and 49 K for x=0.2 and 0.3 respectively and indicating transition from antiferromagnetic to ferromagnetic coupling between ions in the structure. This study provides additional data for the magnetic characteristics of doped like-123 crystalline structures with oxyanions.