STRUCTURAL AND SUPERCONDUCTING PROPERTIES OF Bi₂Sr₂Ca_1−xPr_xCu₂O_y

Abstract

Solid solutions of Bi 2 Sr 2 Ca 1−x Pr x Cu 2 O y (0 ≤ x ≤ 0.6) have been synthesized. The crystal structure and superconducting properties of the samples were examined by XRD and dc electrical resistivity measurements. Linear increase in normal state resistivity is observed with increasing Pr-content (x) for 0 ≤ x ≤ 0.55. Decrease in T c is observed with increasing x and metal–insulator transition is observed around x = 0.55. Although increase in normal state resistivity leads to decrease in T c value, we do not find any definite correlation between these parameters. The conduction mechanism in the semi-conducting sample is found to be Variable Range Hopping. From the decrease of c lattice parameter the possibility of existence of Pr ions in +4 state besides +3 state is inferred.