Determination of the valence of Pr in (Eu1.5−xPrxCe0.5)Sr2Cu2NbO10superconducting compounds by electron-energy-loss spectroscopy
| Autor: | S. C. Cheng, Harry B. Radousky, T.J. Goodwin, R.N. Shelton, Vinayak P. Dravid |
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| Rok vydání: | 1996 |
| Předmět: | |
| Zdroj: | Physical Review B. 53:11779-11783 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.53.11779 |
| Popis: | 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 (${\mathrm{Eu}}_{1.5\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Pr}}_{\mathit{x}}$${\mathrm{Ce}}_{0.5}$)${\mathrm{Sr}}_{2}$${\mathrm{Cu}}_{2}$${\mathrm{NbO}}_{10}$ compounds. EELS analysis, in reference to Ce ${\mathit{M}}_{4,5}$ edges, clearly indicates that the energy onset, ${\mathit{M}}_{5}$/${\mathit{M}}_{4}$ intensity ratio and the fine structure of the ${\mathit{M}}_{5}$ and ${\mathit{M}}_{4}$ 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 f-electron hybridization remain viable candidates to explain the lack of superconductivity in Pr-based cuprates. \textcopyright{} 1996 The American Physical Society. |
| Databáze: | OpenAIRE |
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