Preparation and Physical Properties of (PrxY1-x)1+δBa2-δCu3Oy

The Pr-Y solid-solution of the “1-2-3” crystal structure is expressed as (PrxY1-x)1+δBa2-δCu3Oy, with δ ranging from 0 (x=0) to 0.06 (x=1); a small percentage of the Ba sites are occupied by Pr ions. This Pr-Y solid-solution for x>0.5 is nonsuperconducting and does not show metallic conduction. At the metal-semiconductor boundary (x=0.5), the average valence of the Cu ion is smaller by only ca. 0.1 than that of the 90 K superconductor YBa2Cu3O7 (x=0). The relation between the lattice parameters and ionic radii at the Y site is completely different from the empirical relation obtained so far for REBa2Cu3Oy crystals (RE=Y and trivalent lanthanide elements).