Determination of the valence of Pr in (Eu1.5−xPrxCe0.5)Sr2Cu2NbO10 superconducting compounds by electron-energy-loss spectroscopy
S. C. Cheng, V. P. Dravid, T. J. Goodwin, R. N. Shelton, H. B. Radousky
DOI 10.1103/PhysRevB.53.11779 · Physical Review B
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Abstract
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 (Eu1.5−xPrxCe0.5)Sr2Cu2NbO10 compounds. EELS analysis, in reference to Ce M4,5 edges, clearly indicates that the energy onset, M5/M4 intensity ratio and the fine structure of the M5 and M4 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 f-electron hybridization remain viable candidates to explain the lack of superconductivity in Pr-based cuprates. © 1996 The American Physical Society.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| (Eu1.5-xPrxCe0.5)Sr2Cu2NbO10 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| (R1.5Ce0.5)Sr2Cu2NbO10 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 28 | Pressure not reported | onset |
| Pr1.83Ce0.17CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| Bi2Sr2Ca1-xPrxCu2O8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
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