کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1331139 | 978997 | 2010 | 7 صفحه PDF | دانلود رایگان |
X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) have been applied to examine the electronic structure of the rare-earth transition-metal oxyarsenides REFeAsO (RE=Ce, Pr, Nd, Sm, Gd) and CeNiAsO. Within the metal–arsenic layer [MAs], the bonding character is predominantly covalent and the As atoms are anionic, as implied by the small energy shifts in the M 2p and As 3d XPS spectra. Within the rare-earth–oxygen layer [REO], the bonding character is predominantly ionic, as implied by the similarity of the O 1s binding energies to those in highly ionic oxides. Substitution with a smaller RE element increases the O 1s binding energy, a result of an enhanced Madelung potential. The Ce 3d XPS and Ce L3-edge XANES spectra have lineshapes and energies that confirm the presence of trivalent cerium in CeFeAsO and CeNiAsO. A population analysis of the valence band spectrum of CeNiAsO supports the formal charge assignment [Ce3+O2−][Ni2+As3−].
In the rare-earth oxyarsenides REFeAsO, the oxygen 1s binding energy increases upon substitution with a smaller RE metal (from La to Gd).Figure optionsDownload as PowerPoint slide
Journal: Journal of Solid State Chemistry - Volume 183, Issue 7, July 2010, Pages 1477–1483