Effects of Oxygen Stoichiometry on the Critical Temperature and the Crystal Structure of Er_1-xPr_xBa₂Cu₃O_7-δ, Sm_1-xPr_xBa₂Cu₃O_7-δ and Nd_1-x Pr_xBa₂Cu₃O_7-δ

Abstract

For ceramic samples of HTC-superconductors REBa₂Cu₃O_{7_δ} (RE=Er, Sm and Nd) in which rare earth (RE) ions were partially substituted by praseodymium ions the critical temperature Tc and the crystal structure were determined as a function of the oxygen content of the compound. Tc was inferred from standard four-probe resistivity measurements and the crystal structures from powder X-ray diffraction patterns. For all fully oxidized samples the value of T_c decreases rapidly with increasing percentage of Pr-atoms. Samples of Er_1-xPr_xBa₂Cu₃O_7-δ with x = 0.1,0.2,0.3,0.35, 0.4, 0.5 and 0.53, Sm_1-xPr_xBa₂Cu₃O_7-δ with x = 0.1 and 0.2 and Nd_1-xPr_xBa₂Cu₃O_7-δ with x = 0.1, 0.2 and 0.3 show no pronounced 90 K plateau in T_c as a function of oxygen content. It seems that for increasing praseodymium concentration the 60 K plateau is more extended than for undoped samples. The value of δ for which superconductivity vanishes, decreases only slightly with increasing x.

died on June 30th, 1991