L. Cheng et al., HIGH-RESOLUTION STRUCTURAL STUDY OF ZINC ION INCORPORATION AT THE CALCITE CLEAVAGE SURFACE, Surface science, 415(1-2), 1998, pp. 976-982
The atomic-scale structure of Zn2+ incorporated at the CaCO3 (10 (1) o
ver bar 4) surface by adsorption from solution was determined by X-ray
standing wave triangulation and surface extended X-ray absorption fin
e structure spectroscopy. At low coverage (approximately 0.1 ML), Zn2 substitutes for Ca2+ in the surface layer. Structural relaxation of t
he adjacent in-plane CO32- ions in the host surface is shown by the re
duced nearest-neighbor distance of Zn-O relative to Ca-O. Relaxation o
f the Zn2+ ion in the out-of-plane direction is shown by the displacem
ent of its lattice position from the ideal Ca2+ position. These relaxa
tions, resulting in a local lattice buckling feature at the Zn2+ adsor
ption site, can be fully explained as the combined effect of the elect
rostatic relaxation of the nearest-neighbor anions in response to the
smaller size of Zn2+, and the bonding asymmetry due to surface truncat
ion. (C) 1998 Published by Elsevier Science B.V. All rights reserved.