Europium substitution effects in superconducting YBa2Cu4O8 synthesized under one atmosphere oxygen pressure

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Journal Title
Journal ISSN
Volume Title
School of Chemical Technology | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
1994
Major/Subject
Mcode
Degree programme
Language
en
Pages
4154-4158
Series
Physical Review B, Volume 50, Issue 6
Abstract
Y1−xEuxBa2Cu4O8 powder samples, with x=0, 0.25, 0.5, 0.75, and 1.0, were synthesized at ambient pressure using either an acetate-tartrate sol-gel method or a LiF flux process. The lattice parameters and purity of the samples were checked using X-ray diffraction. The superconducting transition was monitored by magnetic-susceptibility measurements. Replacing yttrium with europium increased the unit-cell volume, decreased the orthorhombicity (b/a) and the critical temperature. The hyperfine interactions at the europium site were studied by Eu151 Mössbauer spectroscopy. The complete quadrupole Hamiltonian of the 21.5-keV γ transition of Eu151 was successfully applied in the analyses of the Mössbauer spectra. The Mössbauer parameters obtained were found to resemble those measured for the EuBa2Cu3Cu3O7−δ (1:2:3) system. It was demonstrated that magnetic alignment of the crystallites could not be obtained with an 11.7-T field, contrary to the 1:2:3 and other high-Tc systems. The magnetic susceptibility for 1:2:4 single crystals appears to be isotropic.
Description
Keywords
superconducting, europium
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Citation
Lindén, J. & Lippmaa, M. & Miettinen, J. & Tittonen, I. & Katila, T. & Kareiva, A. & Karppinen, Maarit & Niinistö, L. & Valo, J. & Leskelä, M. 1994. Europium substitution effects in superconducting YBa2Cu4O8 synthesized under one atmosphere oxygen pressure. Physical Review B. Volume 50, Issue 6. 4154-4158. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.50.4154.