Bonding and structure of Nd/sup 3 +/ in BeF/sub 2/ glass by XANES and EXAFS spectroscopy
The L/sub III/, L/sub II/, and L/sub I/ XANES and EXAFS of Nd/sup 3 +/ have been measured using synchrotron radiation from SPEAR at Stanford Synchrotron Radiation Laboratory to probe the bonding and structure of Nd/sup 3 +/ in a BeF/sub 2/ glass containing 4 mol % NdF/sub 3/. Crystalline NdF/sub 3/ and Nd/sub 2/O/sub 3/ were used as reference compounds to model the chemical environment of Nd/sup 3 +/ in the glass. It is found that in the glass there is a substantial increase in the intensity of the Nd L/sub III/ and L/sub II/ white lines compared with those of crystalline NdF/sub 3/. EXAFS analysis showed that there is a shrinkage of the innermost Nd--F bond distance and a reduction of nearest neighbor fluorine coordination to approx.7 in the glass compared with nine in pure NdF/sub 3/. The sevenfold coordination is in agreement with recent molecular dynamics calculations. Using Slater's atomic shielding constants, the observed increase in white line intensities in the glass was attributed to a covalency effect due to back donation of valence electron from the ligand to the partially filled 4f orbitals of the Nd/sup 3 +/ ions. This study illustrates ability of the combined XANES and EXAFS technique in elucidating the chemical bonding and local structure of a given atomic constituent in glassy solids.
- Research Organization:
- General Electric Corporate Research and Development, Schenectady, New York 12301
- OSTI ID:
- 6315152
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 78:10; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360602* -- Other Materials-- Structure & Phase Studies
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BERYLLIUM COMPOUNDS
BERYLLIUM FLUORIDES
BREMSSTRAHLUNG
CHEMICAL BONDS
CRYSTAL STRUCTURE
ELECTROMAGNETIC RADIATION
ELECTRONIC STRUCTURE
FLUORIDES
FLUORINE COMPOUNDS
GLASS
HALIDES
HALOGEN COMPOUNDS
L SHELL
LIGANDS
NEODYMIUM ADDITIONS
NEODYMIUM ALLOYS
RADIATIONS
RARE EARTH ADDITIONS
RARE EARTH ALLOYS
SPECTRA
SYNCHROTRON RADIATION
X-RAY SPECTRA