Investigation of Radiation Damage in Iron Phosphate Glasses by Soft X-Ray Absorption Spectroscopy: A Powerful Tool for Surface Characterization

Fe K-edge x-ray absorption fine-structure (XAFS) measurements were performed on glass samples of (Fe3O4)0.3(P2O5)0.7 with various amounts of Na2O or UO2. Near-edge and extended XAFS regions are studied and comparisons are made to several reference compounds. We find that iron in the base glass is ∼25% divalent and that the Fe2+ coordination is predominantly octahedral, while Fe3+ sites are roughly split between tetrahedral and octahedral coordinations. Also, we measure roughly one Fe–O–P link per iron. Substitution of Na2O or UO2 up to 15 mol% primarily affects the first Fe–O shell. The results are compared to data from the related material Fe3(P2O7)2.

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Xanes (X-ray absorption near edge structure) of V in vanadium-iron phosphate glasses

Solid State Communications ◽

10.1016/0038-1098(82)90605-6 ◽

1982 ◽

Vol 42 (8) ◽

pp. 547-551 ◽

Cited By ~ 20

Author(s):

A. Bianconi ◽

A. Giovannelli ◽

I. Dovoli ◽

S. Stizza ◽

L. Palladino ◽

...

Keyword(s):

Iron Phosphate ◽

Phosphate Glasses ◽

Edge Structure ◽

X Ray ◽

Vanadium Iron ◽

Iron Phosphate Glasses ◽

X Ray Absorption

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Local environment of iron and uranium ions in vitrified iron phosphate glasses studied by Fe K and U LIII-edge x-ray absorption fine structure spectroscopy

Journal of Materials Research ◽

10.1557/jmr.2000.0284 ◽

2000 ◽

Vol 15 (9) ◽

pp. 1972-1984 ◽

Cited By ~ 40

Author(s):

M. Karabulut ◽

G. K. Marasinghe ◽

C. S. Ray ◽

D. E. Day ◽

G. D. Waddill ◽

...

Keyword(s):

Fine Structure ◽

Average Distance ◽

Iron Phosphate ◽

Phosphate Glasses ◽

Edge Structure ◽

X Ray ◽

Absorption Fine ◽

Uranium Ions ◽

Iron Phosphate Glasses ◽

X Ray Absorption

The local structure of iron and uranium ions in a series of iron phosphate glasses with the general composition (40 – x)Fe2O3–xUO2–60P2O5 and (1–x–y)(40Fe2O3–60P2O5)– xUO2–y(Na2O or CaO) was investigated using Fe K-edge and U LIII-edge x-ray absorption fine structure spectroscopy. Replacing Fe2O3 by UO2 in the glass caused more distortion in the coordination environment of Fe(III) ions. Extended x-ray absorption fine structure fits revealed that the Fe–P bonds observed in the base glass also existed in all the waste-loaded glasses. X-ray absorption near-edge structure showed that the uranium ions were predominantly present as U(IV) in the glasses. Uranium ions were coordinated to approximately 8 ± 1 oxygen atoms and 2.5 ± 0.6 phosphorus atoms at an average distance of 2.47 ± 0.02 and 3.8 ± 0.02 Å, respectively. There were no Fe–U or U–Fe neighbors observed, indicating that uranium ions occupied voids in the glass away from the PO4 units. These conclusions were supported by Mössbauer, x-ray photoelectron, and Raman spectroscopic data.

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Characterization of Radiation Damage at the Nb Site in Natural Pyrochlores and Samarskites by X-Ray Absorption Spectroscopy

MRS Proceedings ◽

10.1557/proc-127-261 ◽

1988 ◽

Vol 127 ◽

Cited By ~ 4

Author(s):

R. B. Greegor ◽

F. W. Lytle ◽

B. C. Chakoumakos ◽

G. R. Lumpkin ◽

J. K. Warner ◽

...

Keyword(s):

Radiation Damage ◽

Long Range ◽

Absorption Spectroscopy ◽

Alpha Decay ◽

Long Range Order ◽

Static Disorder ◽

Annealed Condition ◽

X Ray ◽

X Ray Absorption

ABSTRACTX-ray absorption spectroscopy has been used to investigate the Nb B-site in pyrochlores (A1.2B2O6Y0–1, Fd3m, Z=8) and samarskites (A3B5O16) in both metamict and annealed condition. The XANES and EXAFS measurements indicate significant changes in pyrochlore and smaller changes in samarskite as a result of radiation damage. In the metamict state the Nb site in both pyrochlores and samarskites is similar to Nb in Nb2O5. Short Nb-O (1.65Å) bonds are not disrupted by alpha-decay/recoil-nuclei events as much as longer bonds (2.00Å). This increases the asymmetry and static disorder at the local Nb site while long range order is greatly diminished resulting in considerable distribution in Nb-M distances and bond angles.

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