Local structure of Co{sup 2+} incorporated at the calcite surface: An x-ray standing wave and SEXAFS study
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)
- Environmental Research Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- Department of Materials Science and Engineering, and Institute of Environmental Catalysis, Northwestern University, Evanston, Illinois 60208 (United States)
Following adsorption from a dilute water solution, the lattice site and first-neighbor bonding distances of Co{sup 2+} ions incorporated at the calcite (101(bar sign)4) surface were determined with atomic resolution by the combination of x-ray standing wave triangulation and polarization-dependent surface extended x-ray absorption fine-structure spectroscopy. The incorporated Co{sup 2+} ions selectively occupy the Ca{sup 2+} lattice sites with an inward relaxation of 0.34 Aa. The Co{sup 2+} ions remain octahedrally coordinated, with a first-neighbor Co-O bonding distance of 2.11 Aa. The octahedral coordination suggests that a coadsorbed species from the solution remains bonded to the Co{sup 2+} ion above the surface. The structure of Co{sup 2+} incorporated at the calcite surface is successfully described by a model in which the Co{sup 2+} sites are mainly determined by relaxation due to surface lattice asymmetry, and the first-neighbor Co-O relaxation by reconformation of the adjacent carbonate molecules. (c) 2000 The American Physical Society.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- OSTI ID:
- 20215507
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 61, Issue 7; Other Information: PBD: 15 Feb 2000; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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