Synthesis of orthorhombic phase Pr-1(Ba0.55Pr0.45)(2)((Cu0.95Fe0.05)-Fe-57)(3)O-z and a Mossbauer study of the local oxygen environment of probe ironatoms

The single-phase samples Pr1+xBa2-xCu3Oz and Pr1+xBa2-x(Cu0.95Fe0.05)(3)O-z were synthesized for the first time. The phases are characterized by the l imiting degree of substitution of praseodymium for barium, x = 0.9, and by the orthorhombic distortion of the unit cell (a = 3.888-3.891 Angstrom, b = 3.843-3,848 Angstrom, c = 11.556-11.635 Angstrom). Introducing the Mossbau er label Fe-57 into the sample of the composition Pr1.9Ba1.1 (Cu0.95Fe0.05) (3)O-z made it possible to study the local structure of the synthesized ort horhombic phase. Experimental data permit the assumption that the Pr1.9Ba1. 1Cu3Oz phase is isostructural with Nd1.9Ba1.1Cu3Oz and contains extra oxyge n atoms located in fixed positions, which are vacant at x = 0, in the oxyge n-deficient copper-oxygen planes.