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Determination of the valence of Pr in (Eu{sub 1.5{minus}{ital x}}Pr{sub {ital x}}Ce{sub 0.5})Sr{sub 2}Cu{sub 2}NbO{sub 10} superconducting compounds by electron-energy-loss spectroscopy

Journal Article · · Physical Review, B: Condensed Matter
;  [1]; ;  [2];  [3]
  1. Department of Materials Science and Engineering, Science and Technology Center for Superconductivity, Northwestern University, Evanston, Illinois 60208 (United States)
  2. Department of Physics, University of California, Davis, California 95616 (United States)
  3. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
The issue of the valence state of praseodymium (Pr) in Pr-containing cuprates is addressed using electron-energy-loss spectrometry (EELS) in a transmission electron microscope (TEM) on (Eu{sub 1.5{minus}{ital x}}Pr{sub {ital x}}Ce{sub 0.5})Sr{sub 2}Cu{sub 2}NbO{sub 10} compounds. EELS analysis, in reference to Ce {ital M}{sub 4,5} edges, clearly indicates that the energy onset, {ital M}{sub 5}/{ital M}{sub 4} intensity ratio and the fine structure of the {ital M}{sub 5} and {ital M}{sub 4} edges of a Pr are consistent with Pr valence of +3. These results eliminate theoretical descriptions on these compounds based upon a Pr +4 valence state and a suppression of carrier states. Localized holes, magnetic interactions, and {ital f}-electron hybridization remain viable candidates to explain the lack of superconductivity in Pr-based cuprates. {copyright} {ital 1996 The American Physical Society.}
Research Organization:
Lawrence Livermore National Laboratory
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
285244
Journal Information:
Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 17 Vol. 53; ISSN PRBMDO; ISSN 0163-1829
Country of Publication:
United States
Language:
English