  The influence of low-level Pr substitution in Y1-xPrxBa2Cu3O(7-delta) single
crystals on the anisotropy of the superconducting state parameters was
investigated by torque magnetometry in magnetic fields of up to 9 T. An
averaged anisotropy parameter, \gamma, of 7.4 was found and no influence of the
Pr ion concentration on \gamma was observed up to a Pr content of 2.4%. A
pronounced maximum at angles between 0.5 and 1 degree out of the ab-plane was
observed in all crystals in the irreversible angular dependence of the torque.
This maximum is attributed to intrinsic pinning associated with kinked
vortices. The variation of the irreversible torque with the substitution level
indicates the influence of the Pr content on pinning within the CuO2 planes,
even though the anisotropy of the superconducting state parameters is not
affected.
