High field magneto-transport and magnetization study of   Y1-xCaxBa2Cu3O7-{\delta}(x = 0.0-0.25)
  We report DC isothermal magnetization, global critical current density (JC), Intra-grain critical current density (JCintra) and resistive upper critical field (Bc2) of polycrystalline Y1-xCaxBa2Cu3O7-{\delta} (YBCO); x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25. Ca doping at Y sites in YBCO superconductor results in flux pinning property, which can enhance the critical current density and upper critical fields. JC and JCintra are experimentally calculated through DC isothermal magnetization measurement (M-H), employing the well known Bean's critical model. It is observed that both type of current densities (global and intra) enhance with lower doped (5%) samples and can be accounted in terms of reaching maximum of pinning centers and improved grain couplings nature. The upper critical field (Bc2) increases with Ca content being consistent with enhanced grain coupling nature of doped samples. 
N. P. Liyanawaduge, Anuj Kumar, Rajveer Jha, B. S. B. Karunarathne,   and V. P. S. Awana
cond-mat.supr-con