Ernö Kuzmann, Markus Mair, Z. Klencsár, Z. Homonnay, A. Vertes, Gerhard Gritzner,
"Mössbauer Spectroscopy and Preparation of Hg-1223, Tl-1223 and Tl-1212 Superconductors"
, in Journal of Radioanalytical and Nuclear Chemistry, Vol. 246, Seite(n) 107 - 112, 6-2000, ISSN: 1588-2780, Preparation and Mössbauer spectroscopy of Hg-1223, Tl-1223 and Tl-1212 superconductors, E. Kuzmann, M. Mair, Z. Klencsar, A. Vertes and G. Gritzner, J. Radioanal. Nucl. Chem., 246 (2000) 107 - 112, ISSN 0236-5731
Original Titel:
Mössbauer Spectroscopy and Preparation of Hg-1223, Tl-1223 and Tl-1212 Superconductors
Sprache des Titels:
Englisch
Original Kurzfassung:
The introduction of the Mössbauer nuclei 57Fe into (Hg0.3Pb0.4)(Sr0.8Ba0.2)2Ca2Cu3Oy (Hg-1223 phase) and of 57Fe and 151Eu into Tl-1212 and Tl-1223 superconductors was investigated. Samples of high phase purity were obtained. Scanning electron microscopy and optical microscopy in normal and polarized light were employed to study the microstructure of the specimens. Energy dispersive X-ray analysis showed that 57Fe - in the case of Hg-based samples - and 57Fe as well as 151Eu - in the case of the Tl-based compounds - entered superconducting phases.
The two doublets found for the 57Fe Mössbauer spectra in both the Hg-1223 and the Tl-1223 phase referred to two different micro-environments of Fe3+. The assignment of the 57Fe Mössbauer spectra was made under the assumption that Fe favored the 1223 phase. Fe3+ may replace Cu in both the square pyramidal, five-fold oxygen coordinated Cu sites between the Ca and Ba-(Sr)-O layers and in the square planar, four-fold oxygen coordinated Cu sites between the two Ca layers in the superconducting phases in both the Hg- and the Tl-based materials. From the relative areas of the two doublets we concluded the Fe3+ preferred the square planar Cu site.
Incorporation of Eu3+ into the superconducting phase favored the formation of the Tl-1212 phase. Mössbauer spectroscopy showed that Eu3+ entered the Ca-site.
Sprache der Kurzfassung:
Englisch
Englischer Titel:
Preparation and Mössbauer spectroscopy of Hg-1223, Tl-1223 and Tl-1212 superconductors
Englische Kurzfassung:
The introduction of the Mössbauer nuclei 57Fe into (Hg0.3Pb0.4)(Sr0.8Ba0.2)2Ca2Cu3Oy (Hg-1223 phase) and of 57Fe and 151Eu into Tl-1212 and Tl-1223 superconductors was investigated. Samples of high phase purity were obtained. Scanning electron microscopy and optical microscopy in normal and polarized light were employed to study the microstructure of the specimens. Energy dispersive X-ray analysis showed that 57Fe - in the case of Hg-based samples - and 57Fe as well as 151Eu - in the case of the Tl-based compounds - entered superconducting phases.
The two doublets found for the 57Fe Mössbauer spectra in both the Hg-1223 and the Tl-1223 phase referred to two different micro-environments of Fe3+. The assignment of the 57Fe Mössbauer spectra was made under the assumption that Fe favored the 1223 phase. Fe3+ may replace Cu in both the square pyramidal, five-fold oxygen coordinated Cu sites between the Ca and Ba-(Sr)-O layers and in the square planar, four-fold oxygen coordinated Cu sites between the two Ca layers in the superconducting phases in both the Hg- and the Tl-based materials. From the relative areas of the two doublets we concluded the Fe3+ preferred the square planar Cu site.
Incorporation of Eu3+ into the superconducting phase favored the formation of the Tl-1212 phase. Mössbauer spectroscopy showed that Eu3+ entered the Ca-site.
Journal:
Journal of Radioanalytical and Nuclear Chemistry
Volume:
246
Seitenreferenz:
107 - 112
Erscheinungsmonat:
6
Erscheinungsjahr:
2000
Notiz zum Zitat:
Preparation and Mössbauer spectroscopy of Hg-1223, Tl-1223 and Tl-1212 superconductors, E. Kuzmann, M. Mair, Z. Klencsar, A. Vertes and G. Gritzner, J. Radioanal. Nucl. Chem., 246 (2000) 107 - 112, ISSN 0236-5731
Forschungs-