X-ray absorption studies of CeO/sub 2/, PrO/sub 2/, and TbO/sub 2/. II. Rare-earth valence state by L/sub III/ absorption edges

Journal Article · Wed Jul 15 04:00:00 EDT 1987 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.36.1750· OSTI ID:6229553

Dexpert, H; Karnatak, R C; Esteva, J h; Connerade, J P; Gasgnier, M; Caro, P E; Albert, L

The L/sub III/ absorption edges of fluorite-structure-related CeO/sub 2/, PrO/sub 2/, and TbO/sub 2/ show four well-resolved spectral features. The systematic trend in their positions and relative intensities suggests the presence of a specific valence state of the rare-earth atom in these oxides. The present study reveals an appreciable 4f-2p oxygen overlap in the valence band following the complete delocalization of the outermost 4f electron. Of the two main structures, the highest-energy one is interpreted as due to the localized 4f state and the additional presence of a hybridized 4f external state which we denote as 4f-bar, is evidenced by the lower-energy peak. The weaker shoulder and preabsorptionlike feature are attributed to a shakedown effect due to the presence of an additional screening electron. This effect occurs both for the localized and for the extended orbitals of f symmetry, and a weaker structure therefore attaches to each of the strong peaks. The coexistence of localized and extended states is interpreted within a double-valley-potential model.

• Research Organization: Laboratoire pour l'Utilisation du Rayonnement Electromagnetique, Btiment 209d, Universite Paris-Sud, 91405 Orsay, France iand, 92195 Meudon Cedex, France
• OSTI ID: 6229553
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 36:3; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ABSORPTION SPECTRA
CERIUM COMPOUNDS
CERIUM OXIDES
CHALCOGENIDES
ELECTRONS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY LEVELS
F STATES
FERMIONS
HYBRIDIZATION
LEPTONS
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
P STATES
POTENTIALS
PRASEODYMIUM COMPOUNDS
PRASEODYMIUM OXIDES
RARE EARTH COMPOUNDS
SCREENING
SPECTRA
TERBIUM COMPOUNDS
TERBIUM OXIDES
X-RAY SPECTRA