Abstract: EXAFS analyses of YBCO doped with Pr approve that the O position in this system changes with the Pr concentration x. With increasing x, the deformation of CuO₂ plane greater, the O in the Cu-O chain nearer CuO₂ plane, the distance between Ba and O3 longer. All these tructure changes in the Y_1-xPr_xBa₂Cu₃O_7-δ system make the carrier density decreas and make the carrier strongly localize, which causes the change of superconductivity.

Key words: Y_1-xPr_xBa₂Cu₃O_7-δsystem, EXAFS analysis, superconductivity