CIS-TRANS TRANSITION AND CHARGE TRANSFER IN GLAUCONITE

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Submitted on 1 Jan 1979

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CIS-TRANS TRANSITION AND CHARGE TRANSFER IN GLAUCONITE

R. Quartier, A. Govaert, C. Dauwe, H. Pollak

To cite this version:

R. Quartier, A. Govaert, C. Dauwe, H. Pollak. CIS-TRANS TRANSITION AND CHARGE TRANSFER IN GLAUCONITE. Journal de Physique Colloques, 1979, 40 (C2), pp.C2-488-C2-488.

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CIS-TRANS TRANSITION AND CHARGE TRANSFER IN GLAUCONITE

R. Quartier, A. Govaert: C. Dauwe and H. Pollak

Vniversitd Nationale du Z a h , Ddpartement de Physique, Groupe de Z'Etat Solide, Canpus de Kinshasa, zacre

.

+ ~ ~ k s u n i o e r s i t e i t Cent, Laboratoriwn voor Magnetisme, BeZgiwn.

R6sumB.- Un glauconite a QtE Etudig par spectromLtrie Gssbauer. Le rapport ~ e ~ + / ~ e ~ + diminue avec la temperature et pour les ions foniques on observe seulement une transition cis-trans, avec un maximum B 225 K environ.

Abstract.- Glauconite has been investigated by Mzssbauer Spectroscopy at temperature varying between 77 K and 300 K. The analysing model used was the one proposed by Govaert and Quartier / I / . 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 :

l o 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 tran- sitions 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.

References

/ I / Govaert, A. and Quartier, R., this conference.

/2/ Heilmann, I . U . , Olsen, N.B. and Olsen, J.S., (to be published).

/ 3 / Bancroft, G.R., Mzssbauer Spectroscopy, (Mc Graw

Hill, London) 1973.

/4/ Dambly, M . , Pollak, H., Quartier, R. and Bruyneel, W., J. Phys. C

2

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792171