J. Phys. Colloques
Volume 40, Numéro C2, Mars 1979
International Conference on The Applications of The Mössbauer Effect
Page(s) C2-488 - C2-488
International Conference on The Applications of The Mössbauer Effect

J. Phys. Colloques 40 (1979) C2-488-C2-488

DOI: 10.1051/jphyscol:19792171


R. Quartier1, A. Govaert2, C. Dauwe1 and H. Pollak1

1  Université Nationale du Zaïre, Département de Physique, Groupe de l'Etat Solide, Campus de Kinshasa, Zaïre.
2  Rÿksuniversiteit Gent, Laboratorium voor Magnetisme, Belgium.

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.

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.