NUKLEONIKA 2007, 52(Supplement 1):S81-S84

57Fe MÖSSBAUER SPECTROSCOPY OF ANNEALED METAMICT DAVIDITE

Dariusz Malczewski1, Janusz F. Fr¹ckowiak2, Evgeny V. Galuskin1

1 Faculty of Earth Sciences, University of Silesia, 60 Bêdziñska Str., 41-200 Sosnowiec, Poland
2 Faculty of Computer and Materials Science, University of Silesia, 12 Bankowa Str., 40-007 Katowice, Poland

This paper reports preliminary results of 57Fe Mössbauer spectroscopy and X-ray diffraction (XRD) studies of metamict davidite samples (La,Ce,Ca,Th)(Y,U,Fe)(Ti,Fe,Mn)20(O,OH)38 after high temperature annealing in an argon atmosphere. The Mössbauer spectra show a gradual decrease of quadrupole splitting and line width values of an Fe3+ doublet with increasing annealing temperature. Rather unexpected feature of these spectra for an Fe2+ doublet is a considerable increase of the line width with progressive crystallinity and a simultaneous decrease of both quadrupole splitting and isomer shift values. Changes of the hyperfine parameters as a function of the annealing temperature appeared as sensitive indicators of the thermal recrystallization process of metamict davidite similar to metamict silicates.