Positron annihilation study of the OT phase transition for Eu1+xBa2xCu3O7 superconductors Academic Article uri icon

abstract

  • The effects of Eu substituting for Ba on structural and superconducting properties were investigated for a series of superconductors Eu 1+xBa2-xCu3O7- (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.18, and 0.2). With Eu content increasing, the random substitution of excessive Eu for Ba ion forms a Eu-Ba non-stoichiometric distribution on Ba site, which deviates from the ideal 123 phase stoichiometry. The analysis of crystallographic structure shows that the solid solubility x of Eu on Ba site is over 0.2. Eu1+xBa 2-xCu3O7- take on an orthorhombic-tetragonal (O-T) phase transition from x = 0.06, and end in x = 0.18. Corresponding to the O-T phase transition, superconducting critical temperature Tc rapidly decreases with Eu content increasing, which is attributed to the decline of carrier density and the proximity effects of non-superconducting clusters. The positron annihilation measurements show anomalous changes for lifetime spectra and Doppler-broadened radiation spectra when the O-T phase transition occurs. By the model of excessive oxygen defects in Cu-O chain regions, we discuss effects of Eu-Ba non-stoichiometric distribution on structural and superconducting properties. 2003 Elsevier B.V. All rights reserved.

published proceedings

  • Physica C: Superconductivity

author list (cited authors)

  • Li, Y., Liu, Y., Duan, R., Xiong, X., Wang, B., Cao, G., ... Ross, J. H

publication date

  • January 1, 2004 11:11 AM