Effects of Sr-doping on the phase transition and electrical properties in PrBa2−xSrxCu3Oy

Effects of Sr-doping on PrBa2Cu3Oy have been investigated in particular reference to the relationship between a phase transition and electrical properties. The orthorhombic to tetragonal (O-T) phase transition has been found to occur at a certain concentration (x) of dopant Sr when the synthesized compound PrBa2−xSrxCu3Oy is annealed in air- or oxygen-atmosphere. However, this transition does not occur for samples annealed in Ar-atmosphere. The resistivity ρ has been found to sharply rise together with occurrence of the O-T transition. This sharp rise in ρ has been first observed in the present work. In contrast, ρ of samples annealed in Ar-atmosphere behaves only as a decreasing function of x, exhibiting no sharp rise. The magnetization has also been found to behave differently according to the annealing process. The O-T transition is described in terms of Pr-incorporation into Ba site and rearrangement of oxygen atoms. The relationship between the crystalline transition and behavior of ρ is described in terms of a percolation process.