Magnetic properties of high-oxygen pressure prepared PrBa2Cu3O7-y cuprates

High oxygen pressure annealed PrBa2Cu3O7−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 TN(Pr)=19 K was observed for PrBa2Cu3O6.95. Comparison with other Pr/Ba intersubstituted Pr1−xBa2−xCu3O7−y cuprates is discussed.