Neutron powder diffraction study on Pr(Ba1-xSrx)2Cu3Oy compounds with 0 ≤ x ≤ 0.5

The crystal structure of Pr(Ba1-xSrx)(2)Cu3Oy Compounds with 0 <= x <= 0.5 has been investigated by high-resolution neutron powder diffraction measurements at room temperature. The bulk samples were prepared by sintering at high temperature under reducing atmosphere. The solubility range of Sr in Pr(Ba1-xSrx)(2)Cu3Oy was found to be 0 <= x <= 0.5. The Rietveld refinement results revealed that Sr ions occupied only the Ba sites, and Pr ions could not occupy the Ba sites. Substitution of Sr for the Ba site induces oxygen disorder in the Cu-O layer. The distance of Pr-O between Pr and oxygen on the CuO2 plane does not show obvious change for x <= 0.3. Above x = 0.3, the distance of Pr-O gradually increases with x. These results indicate that both reductive condition and Sr substitution play an important role in weakening the hybridization between the Pr 4f and O 2p orbital in PrBa2Cu3Oy. (c) 2006 Elsevier B.V. All rights reserved.