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Fe-57 Mossbauer effect study of bannisterite: a modulated 2 : 1-type phyllosilicate

Ferrow, Embaie LU (2006) In Mineralogical Magazine 70(2). p.187-199
Abstract
Bannisterite is a modulated 2:1-type phyllosilicate having ten octahedral sites with hydroxyl groups in trans, cis and combined trans-cis configurations. Each octahedral site, depending on its proximity to the layer modulation, is exposed to a different degree of distortion. The electric field gradient at the Fe site and the site distortion are used to propose a model for the site assignment and oxidation mechanism in bannisterite. The results show that two models are compatible with the experimental results of fitting the spectrum of bannisterite. However, the model which allows for site distortion accounts better for the observed line overlap of the Fe-[6](2+) sites. Accordingly, the octahedral sites with a greater degree of distortion... (More)
Bannisterite is a modulated 2:1-type phyllosilicate having ten octahedral sites with hydroxyl groups in trans, cis and combined trans-cis configurations. Each octahedral site, depending on its proximity to the layer modulation, is exposed to a different degree of distortion. The electric field gradient at the Fe site and the site distortion are used to propose a model for the site assignment and oxidation mechanism in bannisterite. The results show that two models are compatible with the experimental results of fitting the spectrum of bannisterite. However, the model which allows for site distortion accounts better for the observed line overlap of the Fe-[6](2+) sites. Accordingly, the octahedral sites with a greater degree of distortion are assigned to the Fe-[6](2+) with lower electric quadrupole splitting, and the octahedral sites with lower site distortion are assigned to the Fe-[6](2+) with higher electric quadrupole splitting. Moreover, the ease of oxidation decreases in the order trans > trans-cis > cis. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
electric field gradient, distortion, bannisterite, Mossbauer, assignment, site
in
Mineralogical Magazine
volume
70
issue
2
pages
187 - 199
publisher
Mineralogical Society of Great Britain and Ireland
external identifiers
  • wos:000238074400004
  • scopus:33745065819
ISSN
0026-461X
DOI
10.1180/0026461067020323
language
English
LU publication?
yes
id
973aeab3-3a9b-4a92-a720-15640662b2ec (old id 406764)
date added to LUP
2007-10-02 19:50:52
date last changed
2019-02-20 03:51:44
@article{973aeab3-3a9b-4a92-a720-15640662b2ec,
  abstract     = {Bannisterite is a modulated 2:1-type phyllosilicate having ten octahedral sites with hydroxyl groups in trans, cis and combined trans-cis configurations. Each octahedral site, depending on its proximity to the layer modulation, is exposed to a different degree of distortion. The electric field gradient at the Fe site and the site distortion are used to propose a model for the site assignment and oxidation mechanism in bannisterite. The results show that two models are compatible with the experimental results of fitting the spectrum of bannisterite. However, the model which allows for site distortion accounts better for the observed line overlap of the Fe-[6](2+) sites. Accordingly, the octahedral sites with a greater degree of distortion are assigned to the Fe-[6](2+) with lower electric quadrupole splitting, and the octahedral sites with lower site distortion are assigned to the Fe-[6](2+) with higher electric quadrupole splitting. Moreover, the ease of oxidation decreases in the order trans > trans-cis > cis.},
  author       = {Ferrow, Embaie},
  issn         = {0026-461X},
  keyword      = {electric field gradient,distortion,bannisterite,Mossbauer,assignment,site},
  language     = {eng},
  number       = {2},
  pages        = {187--199},
  publisher    = {Mineralogical Society of Great Britain and Ireland},
  series       = {Mineralogical Magazine},
  title        = {Fe-57 Mossbauer effect study of bannisterite: a modulated 2 : 1-type phyllosilicate},
  url          = {http://dx.doi.org/10.1180/0026461067020323},
  volume       = {70},
  year         = {2006},
}