Epitaxial growth of otavite on calcite observed in situ by synchrotron X-ray scattering
- Argonne National Lab., IL (United States)
Synchrotron X-ray reflectivity and X-ray diffraction techniques were used to characterize an otavite (CdCO{sub 3}) overgrowth during its precipitation from an aqueous solution onto a calcite (1014) cleavage surface. X-ray reflectivity was used to measure the otavite thickness and the roughness of the calcite/otavite and otavite/fluid interfaces. Specular and off-specular X-ray diffraction were used to measure the crystallographic orientation and long-range atomic order of the otavite overgrowth. The otavite grew coherently with a (1014) growth plane oriented parallel to the calcite (1014) cleavage surface. The average growth rate of the otavite for the first 9 hours was 15 {angstrom} {center_dot} h{sup {minus}1}. During the early growth stage ({le} 50 {angstrom}), the otavite (1014) lattice spacing (d-value) was compressed by as much 2.2% in the direction perpendicular to the calcite cleavage surface. As the otavite thickness increased, this d-value approached that of bulk otavite. At a thickness of 443 {angstrom}, the otavite was determined to be of single-crystal quality (0.4{degrees} mosaic) and epitaxial with calcite. This study demonstrates a new and accurate approach for measuring in situ precipitation rates and growth mechanisms in mineral-fluid systems.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 28816
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 58, Issue 24; Other Information: PBD: Dec 1994
- Country of Publication:
- United States
- Language:
- English
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