Couple proton-electon dynamics in iron-containing phyllosilicates: annite, KFe3AlSi2O10(OH)2 - Mössbauer determination of Fe2+/Fe3+ ratio (N.Hess LDRD, PNNL SCOPE # 90001)
EMSL Project ID
16730
Abstract
The focus of this investigation is coupled proton-electron dynamics in geochemical systems, specifically the redox reactions in annite, an iron-rich hydrous phyllosilicate. This topic is of particular interest to the geochemical community due to the importance of mineral-bound Fe in mediating redox reaction in the geochemical cycle. The specific goal is to map out the role of protons in maintaining charge balance during oxidation/reduction of structural iron in phyllosilicates in aqueous systems and to determine electron-proton pathways in and out of the crystal.
Although there has been appreciable work on this problem, there is little in the way of definitive results because of the non-specific information obtained by conventional methods such as vibrational spectroscopy and the failure to recognize the role of local lattice distortions in determining probable pathways. Using neutron scattering and advanced computational methods we have demonstrated that these local structures play an important role in the transport properties of protons and electrons through the phyllosilicate structure. However in order to publish these results we need confirmation of the Fe2+/Fe3+ ratio of the annites used in our study.
Project Details
Project type
Exploratory Research
Start Date
2005-11-23
End Date
2007-03-21
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members