  In contrast to the "Pr-issue" that neither PrBa2Cu3O7 (Pr123) nor PrBa2Cu4O8
(Pr124) shows superconductivity (SC), we have observed 100%-fraction of SC in
an oxygen-reduced Pr2Ba4Cu7O(15-delta) (Pr247) which has a hybrid structure
that Pr247 = Pr123 + Pr124. It is found that Cu nuclear-spin signals from the
CuO2 planes observed at 300K are completely wiped out down at 2K. Instead,
plane signals at 2K are observed at higher frequencies. This indicates that,
despite the bulk SC, the CuO2 planes in Pr247 are found to be in an insulating
and antiferromagnetically ordered state.
