Other
Scientific paper
Dec 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994gecoa..58.5639r&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 58, Issue 24, pp.5639-5646
Other
5
Scientific paper
Analysis of Se K -edge XAFS spectra of calcite grown from SeO 4 2- -bearing aqueous solutions at 25°C reveals the local environment of Se incorporated in calcite. The position of the Se K -edge is consistent with oxidation state 6+, and the first shell contains four O atoms at a distance of 1.63 Å, confirming that Se is present as the tetrahedral SeO 4 2- complex ion. The second shell is split and is best fitted by approximately 2 Ca atoms at 3.17 Å and approximately 4 Ca atoms at 3.49 Å. The coordination indicated by the split second shell is consistent with substitution of the SeO 4 2- ion in the CO 3 site of the calcite, which has six nearest-neighbor Ca atoms. The large size of the SeO 4 2- ion and its tetrahedral geometry cause significant distortion of the site that is consistent with the observed Se-Ca distances. Two possible models for the local coordination of the SeO 4 2- ion are suggested that involve corner sharing of the SeO 4 tetrahedron with neighboring Ca octahedra. The results suggest that other complex anions--uparticularly the geochemically important SO 4 2- ion, which is also tetrahedral but slightly smaller than SeO 4 2- --may also substitute in the CO 3 site of carbonates.
Lamble Geraldine M.
Lee Jyh-Fu
Reeder Richard J.
Staudt Wilfried J.
No associations
LandOfFree
Mechanism of SeO 4 2- substitution in calcite: An XAFS study does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Mechanism of SeO 4 2- substitution in calcite: An XAFS study, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mechanism of SeO 4 2- substitution in calcite: An XAFS study will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1408397