| Numéro |
J. Phys. Colloques
Volume 40, Numéro C2, Mars 1979
International Conference on The Applications of The Mössbauer Effect
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|
|---|---|---|
| Page(s) | C2-488 - C2-488 | |
| DOI | https://doi.org/10.1051/jphyscol:19792171 | |
J. Phys. Colloques 40 (1979) C2-488-C2-488
DOI: 10.1051/jphyscol:19792171
CIS-TRANS TRANSITION AND CHARGE TRANSFER IN GLAUCONITE
R. Quartier1, A. Govaert2, C. Dauwe1 and H. Pollak11 Université Nationale du Zaïre, Département de Physique, Groupe de l'Etat Solide, Campus de Kinshasa, Zaïre.
2 Rÿksuniversiteit Gent, Laboratorium voor Magnetisme, Belgium.
Résumé
Un glauconite a été étudié par spectrométrie Mössbauer. Le rapport Fe2+/Fe3+ diminue avec la température et pour les ions foniques on observe seulement une transition cis-trans, avec un maximum à 225 K environ.
Abstract
Glauconite has been investigated by Mössbauer Spectroscopy at temperature varying between 77 K and 300 K. The analysing model used was the one proposed by Govaert and Quartier /1/. While isomeric shifts and quadrupole splittings follow the usual almost linear behaviour as a function of temperature, relative intensities as would be expected are not constant. In fact two phenomena are simultaneously observed : 1° The total ferrous content diminishes with lowering temperature in favour of the total ferric content, 2° For ferric ions only a cis-trans transition is observed, showing a maximum at about 225 K. Charge transfer, as already observed in other silicates /2/, is thus also occuring in Glauconites. This charge transfer may account for the green colour of the Glauconites /3/. On the other hand, simultaneously, cis-trans transitions as proton jumps where observed. Those transitions already have been observed in Tourmaline /4/. One might even ask if they do nor occur for all silicates presenting an octahedral environment with four oxygen-and two hydroxyl groups for the iron, or other metals.