T-C-SUPPRESSION MECHANISM OF PR-DOPING IN (R,PR)BA2CU3O7

Neutron inelastic measurements on Y0.52Pr0.48Ba2Cu3O7 have been carrie d out. From the magnetic excitation spectra chi ''(q, omega), it is fo und that the reduction of the hole-carrier concentration p and the ran domness effects introduced by the substitution of Y with Pr suppress t he superconductivity. Based on the hole-trapping model, the origin of the randomness effects can be explained. The R-ion-size dependence of the suppression rate of the superconducting transition temperature, \d T(c)/dx\, can also be explained qualitatively. By measuring the Hall c oefficients R(H) of R(1-x)Pr(x)Ba(2)Cu(3)O(7) (R = Yb, Y, Gd and Sm), \dp/dx\ is found to be insensitive to the species of R. For RBa(2)Cu(3 )O(7) (without Pr atoms), p decreases with increasing R-ion-size, whic h presents another possible explanation of the R-ion-size dependence o f \dT(c)/dx\.