Synthesis conditions and superconductivity in 123-type superconductors

We have synthesized REBa2Cu3O7-delta, where RE=Y, Sm, Gd, and SM(123):Ag un der the identical conditions and characterized R-T and SEM-EDAX measurement s by XRD. It is observed for sample SmBa2Cu3O7-delta with delta=0.3 that su bstitution of 10% Ag in place of Cu reduces T-c by 13 K along with the enha ncement of normal-state resistivity by almost 200 times. When the T-c of th e samples were optimized, it was found that the normal-state resistivity de creases by the substitution of Ag along with a decrease in T-c.