Octahedral versus tetrahedral coordination of Al in synthetic micas determined by XANES
- Universita di Roma Tre (Italy)
- Centre de Recherche sur la Synthese et la Chimie des Mineraux, Orleans (France); and others
We used the JUMBO monochromator at SSRL to measure the Al K-edge X-ray absorption spectra of synthetic micas having variable Al content and occupancy, from 0 to 2/3 in the octahedral M positions, and 0 to 2/3 in the tetrahedral T positions. The measured Al K edges differ markedly, but the differences may have a common explanation: (1) Micas containing 1/3 Al in M or {1/4} Al in T have K edges that differ in the energy and intensity of the first two features, which are related to interaction of Al with its first-shell nearest neighbors (O and OH or F). They are nearly identical to the K edges of reference minerals such as albite (tetrahedral Al only) or grossular (octahedral Al only). (2) Micas containing Al in both M and T have K edges that can be interpreted as a weighed combination of the simple edges. 39 refs., 4 figs., 1 tab.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 543157
- Journal Information:
- American Mineralogist, Vol. 82, Issue 5-6; Other Information: PBD: May-Jun 1997
- Country of Publication:
- United States
- Language:
- English
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