EFFECTIVE ACTIVATION-ENERGY IN MELT-TEXTURED (Y1-XPRX)BA2CU3O7-DELTA

Flux creep experiments are conducted at mu(0)H = 1 T (parallel to c-ax is) on a set of MTG (Y1-xPrx)Ba2Cu3O7-delta (x less than or equal to 0 .08) samples within the temperature region from 4.5 to 75 K. The effec tive activation energy U-eff(J, T) is extracted by employing the proce dure of Maley et al. In comparison with pure YBa2Cu3O7-delta, the effe ctive activation energy and current densities are enhanced for all the Pr-doped samples investigated with an optimal doping effect achieved at x = 0.05 or so. The zero-temperature effective activation energy U- eff(J, 0) is obtained through a constructive scaling procedure for eac h sample and is found to be in qualitative agreement with the theoreti cal prediction from the collective-pinning model.