Abstract
High oxygen pressure annealed PrBa 2 Cu 3 O 7-y (y∼0) cuprates were prepared in order to study the effect of oxygen stoichiometric parameter y on the unusual Pr/Cu magnetic properties and/or recently reported superconductivity. The oxygen-rich orthorhombic 123-chain phase is highly unstable under high-oxygen pressure synthesis and decomposes completely in 10 bar pressure. For a smaller 2 bar prepared sample a relatively clean phase was preserved with an oxygen parameter y = 0.05, as compared with y = 0.11 from a conventional 1 bar flowing oxygen method. No superconductivity can be detected for all high-oxygen pressure prepared samples. Instead, Mott-insulator behavior with anomalous high Pr ordering T N (Pr) = 19 K was observed for PrBa 2 Cu 3 O 6.95 . Comparison with other Pr/Ba intersubstituted Pr 1-x Ba 2-x Cu 3 O 7-y cuprates is discussed. © 2001 American Institute of Physics.