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Compositional control of plane group symmetry in tourmalines : an experimental and computer simulated TEM, crystallographic image processing and Mossbauer spectroscopy study

Ferrow, EA LU ; Wallenberg, LR LU and Skogby, Henrik (1993) In European Journal of Mineralogy 5(3). p.479-492
Abstract
Tourmalines with different compositions show different plane group symmetries in experimental high resolution transmission electron microscopy (HRTEM) when projected along the c-axis. Fe-poor elbaite shows p31m symmetry, while Fe-bearing elbaite shows p3m1 symmetry. Rubellite shows p6 symmetry, while Fe-Mg-Al-bearing tourmaline shows a `pseudo' p6 type of symmetry. Symmetries p3m1 and p6 are not compatible with the space group R3m assigned to tourmaline from X-ray structural determination studies. The perturbations of symmetry from p31m to p6 and `pseudo' p6 depend on the magnitude of the scattering amplitude of the atoms occupying the 3a and 9b sites. Furthermore, computer simulations of elbaite, schorl and dravite show different... (More)
Tourmalines with different compositions show different plane group symmetries in experimental high resolution transmission electron microscopy (HRTEM) when projected along the c-axis. Fe-poor elbaite shows p31m symmetry, while Fe-bearing elbaite shows p3m1 symmetry. Rubellite shows p6 symmetry, while Fe-Mg-Al-bearing tourmaline shows a `pseudo' p6 type of symmetry. Symmetries p3m1 and p6 are not compatible with the space group R3m assigned to tourmaline from X-ray structural determination studies. The perturbations of symmetry from p31m to p6 and `pseudo' p6 depend on the magnitude of the scattering amplitude of the atoms occupying the 3a and 9b sites. Furthermore, computer simulations of elbaite, schorl and dravite show different projected potentials for images down the c-axis. Regions with high mean concentration of light or heavy elements a few unit cells apart are common in Fe-poor elbaite. This results in a marked difference of the distribution contrast in the HRTEM image of elbaite. The Mossbauer effect (ME) spectra of tourmaline are different with different Mossbauer parameters, reflecting the difference in composition. Experimental HRTEM, computer simulation and ME indicate that composition controls symmetry, ME parameters and atomic coordinates in tourmaline, an observation not recorded in other minerals. (Less)
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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
tourmaline, composition, symmetry, TEM, Mössbauer effect
in
European Journal of Mineralogy
volume
5
issue
3
pages
14 pages
publisher
Copernicus GmbH
external identifiers
  • scopus:0027510891
ISSN
0935-1221
language
English
LU publication?
yes
id
b153a384-d74d-4fc1-8b95-3b8774106c7e
date added to LUP
2023-10-31 15:27:13
date last changed
2023-11-03 09:57:24
@article{b153a384-d74d-4fc1-8b95-3b8774106c7e,
  abstract     = {{Tourmalines with different compositions show different plane group symmetries in experimental high resolution transmission electron microscopy (HRTEM) when projected along the c-axis. Fe-poor elbaite shows p31m symmetry, while Fe-bearing elbaite shows p3m1 symmetry. Rubellite shows p6 symmetry, while Fe-Mg-Al-bearing tourmaline shows a `pseudo' p6 type of symmetry. Symmetries p3m1 and p6 are not compatible with the space group R3m assigned to tourmaline from X-ray structural determination studies. The perturbations of symmetry from p31m to p6 and `pseudo' p6 depend on the magnitude of the scattering amplitude of the atoms occupying the 3a and 9b sites. Furthermore, computer simulations of elbaite, schorl and dravite show different projected potentials for images down the c-axis. Regions with high mean concentration of light or heavy elements a few unit cells apart are common in Fe-poor elbaite. This results in a marked difference of the distribution contrast in the HRTEM image of elbaite. The Mossbauer effect (ME) spectra of tourmaline are different with different Mossbauer parameters, reflecting the difference in composition. Experimental HRTEM, computer simulation and ME indicate that composition controls symmetry, ME parameters and atomic coordinates in tourmaline, an observation not recorded in other minerals.}},
  author       = {{Ferrow, EA and Wallenberg, LR and Skogby, Henrik}},
  issn         = {{0935-1221}},
  keywords     = {{tourmaline; composition; symmetry; TEM; Mössbauer effect}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{3}},
  pages        = {{479--492}},
  publisher    = {{Copernicus GmbH}},
  series       = {{European Journal of Mineralogy}},
  title        = {{Compositional control of plane group symmetry in tourmalines : an experimental and computer simulated TEM, crystallographic image processing and Mossbauer spectroscopy study}},
  volume       = {{5}},
  year         = {{1993}},
}