Bismuth Valence in a Tl0.7Bi0.3Sr1.6Ba0.4CaCu2Oy Superconductor from X-Ray Photoemission Spectroscopy
R. Zaleckia, W.M. Wocha, M. Kowalika, b, A. Kołodziejczyka, and G. Gritznerc
aDepartment of Solid State Physics, AGH University of Science and Technology, 30-059 Cracow, Poland
bDepartment of Physics, Rzeszów University of Technology, 35-959 Rzeszów, Poland
cInstitute for Chemical Technology of Inorganic Materials, Johannes Kepler University Linz, A-4040 Linz, Austria
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The X-ray electron photoemission spectra of a Tl0.7Bi0.3Sr1.6Ba0.4CaCu2Oy superconductor were measured with Al Kα and Mg Kα radiation at room temperature. The Bi 4f spectrum was compared to the same spectra of Bi1.75Pb0.35Sr1.9Ca2.05Cu3.05Oy and Tl0.6Pb0.4Sr1.6Ba0.4Ca2Cu3Oy superconductors. In Bi,Pb-based superconductor only one type of Bi3+ ions is present. The Bi 4f spectrum in the Tl,Bi-superconductor consists of two contributions due to the different valences. The component from Bi5+ lines is in higher binding energy than from Bi3+. The ratio of trivalent Bi3+ to pentavalent Bi5+ bismuth ions was calculated from decomposition of the spin-orbit split spectrum of the Bi 4f photoelectrons. The conclusion is that Bi is present in trivalent and in pentavalent form: and the ratio of Bi3+ to Bi5+ is 1.87 ± 0.02.
DOI: 10.12693/APhysPolA.118.393
PACS numbers: 74.72.-h, 74.25.Jb, 79.60.-i