Magnetic-susceptibility and heat-capacity measurements on Pr-rich PrBa_2-xPr_xCu₃O_7-y compounds

Abstract

The compound PrBa₂Cu₃O_7-y, though isostructural to the 90-K superconducting compounds, RBa₂Cu₃O_7-y (R=rare earth and Y), is semiconducting. Moreover, it orders magnetically with T_N~16 K and also exhibits a large electronic specific-heat coefficient y. We have prepared Pr-rich PrBa_2-xPr_xCu₃O_7-y (0≤x≤1) compounds to study the effect of excess Pr at the Ba site on the structure, magnetic ordering, and electronic specific-heat coefficient of this system. It is observed that single-phase compounds in the above series form up to x~0.8. The stoichiometric PrBa₂Cu₃O_7-y is orthorhombic but the compounds with excess Pr form in the closely related tetragonal structure. Magnetic-susceptibility and heat-capacity measurements reveal that both T_N and y decrease with increasing Pr concentration suggesting a common origin underlying the two.