Subsolidus phase relations and crystal structures in the Pr1+xBa2?xCu3O7??system at 950 ?C

Pr1+xBa2?xCu3O7??solid solution was investigated by means of X-ray powder diffraction and Rietveld analysis. Single-phase PrBa2Cu3O7??(Pr123) can be synthesized under a Pr-rich condition by sintering at 950 ?C in air. The solubility of Pr1+xBa2?xCu3O7??solid solution is 0.08?x?0.80. The structure of Pr1+xBa2?xCu3O7??is orthorhombic for 0.08?x<0.30, and transforms into tetragonal for 0.30?x?0.80. To form single-phase Pr123, the Ba sites in the Pr123 structure are partially occupied by excess Pr ions, and the smallest amount of excess Pr is x=0.08. Meanwhile, all Ba ions stay in the Ba sites.