Anomalous Pr ordering, Pr L₃-edge and Cu K-edge XANES studies for the insulating PrBa₂Cu₃O_7-y system

X-ray absorption near-edge structure (XANES) data for the PrBa₂ Cu₃ O_7-y (6.21 ≤ 7-y ≤ 6.95 insulating system with anomalous Pr antiferromagnetic order are reported. Pr L₃-edge XANES indicates that Pr formal valence decreases from 3.17-3.18 for oxygenated samples to 3.09 for oxygen-depleted PrBa₂Cu₃O_6.43, 3.03 for PrBa₂Cu₃O_6.38 and 3.01 for PrBa₂Cu₃O_6.21. The variation of Pr valence indicates that the doped holes initially stay in the CuO_1-y plane and contribute to Cu(I)-Cu(II) transformation in this plane, but gradually move into the CuO₂ bi-layers with PrO₈ cage and result in the appearance of Pr(IV) localized-hole state with increasing oxygen content. Cu K-edge XANES indicates that the average Cu formal valence increases from less than 2 in oxygen-depleted region to a value larger than 2 for oxygenated samples, with the estimated Cu valence of 2.24 for PrBa₂Cu₃O_6.95. The small average Cu formal valence or large Pr formal valence is closely related to the absence of superconductivity.