Crystal Structure and Superconductivity in Ba₂Y1-xPrxCu₃O7-y

Crystal structures and superconductive properties of the solid solution Ba 2 Y 1- x Pr x Cu 3 O 7- y (0≤ x ≤1) are studied. Although Ba 2 Y 1- x Pr x Cu 3 O 7- y has an orthorhombic structure which is isomorphic with Ba 2 YCu 3 O 7- y , T c decreases monotonically with increasing Pr concentration, and superconductivity disappears at around x =0.6. The Rietveld analysis of X-ray powder diffraction data shows that both Cu(1)-O(3) bond length and the structural asymmetry of the Cu(2)O 2 planes increase by the substitution of Pr for Y. Such structural changes induce the carrier density reduction and localization effects, which may cause the suppression of superconductivity in this system.