Observation of Cu-NQR spectrum over whole range of x in Y1-xPrxBa2Cu3O7-y

The Cu NQR spectra were observed over the whole range of x in the paramagne tic state of Y1-xPrxBa2Cu3O7-y. The NQR frequencies, nu(NQR), for both the Cu(2) and Cu(1) sites do not change significantly with increasing x. These results are in marked contrast to the variation of nu(NQR) at the metal-ins ulator transition in YBa2Cu3Ox and La2-xSrxCuO4. This suggests that the dop ed holes in YBa2Cu3O7 still remain in the CuO2 plane even in PrBa2CU3O7, wh ich conflicts with the hole-filling mechanism for the suppression of the su perconductivity in PrBa2Cu3O7 Since our value of nu(NQR) in PrBa2Cu3O7 is d ifferent from that presented in the previous report, the NMR spectrum in th e antiferromagnetic ordered state was reconsidered.