Evidence for Pr3+ in EuBa1.3Pr0.7Cu3O7-delta by Pr-141 Mossbauer spectroscopy

The polycrystalline compound EuBa1.3Pr0.7Cu3O7-delta has been prepared and investigated by the means of Pr-141 Mossbauer spectroscopy. The observed 14 1Pr Mossbauer isomer shift, delta (at T = 4.2 K) = 0.10 (15) mm/s relative to PrF3, reflect a valence state of 3 + for Pr located at the Ba site in Eu Ba1.3Pr0.7Cu3O7-delta. Magnetic order of the Pr sublattice was not observed at T = 4.2 K in contrast with the compound Eu0.3Pr0.7Ba2Cu3O7-delta where magnetic order of the Pr sublattice appears at T = 12 K. Our results explai n why Pr behaves very similar to other 3 + cations (La, Nd) when substitute d for Pa in this system, and suggests that suppression of superconductivity by Pr substituted at the rare earth site is a consequence of the hole fill ing effect. (C) 2000 Elsevier Science B.V. All rights reserved.