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High-Temperature Superconductors and Related Compounds Studied by Mössbauer Spectroscopy
Abstract
57Fe, 119Sn, and 151Eu Mössbauer spectroscopy was used to study the chemical structure, phonon mode changes, and low-temperature phase transformation around the Tc as well as suppression of superconductivity in high-temperature superconductors and related compounds. Anomalous temperature-dependent changes in the total 57Fe spectral area fraction and in the Mössbauer line shift were simultaneously found around the Tc in a EuBa2(Cu0.9957Fe0.01)3O7-d superconductor. These anomalous changes were attributed to phonon softening and low-temperature phase transformation occurring around the superconducting transition. Significant differences were observed between the 57Fe Mössbauer spectra of superconducting EuBa2(Cu0.9957Fe0.01)3O7-d and the isostructural non-superconducting PrBa2(Cu0.9957Fe0.01)3O7-d. The differences were interpreted in connection with the suppression of superconductivity (by hole filling or hybridization of Pr, Cu and O states) in the Pr-containing compound. The unusually high isomer shift value observed in the Pr-containing material can give evidence for the charge transfer mechanism between the Cu(1) chains and the Cu(2) planes and for its role in the suppression of superconductivity.
Copyright
Copyright © 1993 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
