57Fe Mössbauer Spectroscopy of Radiation Damaged Allanites

D. Malczewski a and A. Grabias b a Faculty of Earth Sciences, University of Silesia, Będzińska 60, 41-200 Sosnowiec, Poland b Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warszawa, Poland

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Received: 08 06 2008

Metamict minerals contain radioactive elements that degrade the crystal structure of the minerals. The degradation occurs primarily through progressive overlapping recoil nuclei collision cascades from α-decays of 238U, 232Th, 235U and their daughter products. We report the results of 57Fe Mössbauer spectroscopy, gamma-ray spectrometry and microprobe analysis of three partially metamict allanites, (Ca,Ce,REE)2(Fe2+,Fe3+)(Al,Fe3+)2O[Si2O7][SiO4](OH) where REE stands for rare earth elements. The samples were collected in pegmatites from Reno, Nevada (USA), Franklin, New Jersey (USA) and Nya Bastnas Field (Sweden). The absorbed α-dose for these minerals was found to range from 5.8× 1014 α-decay/mg for the allanite from Reno to 1.9× 1015 α-decay/mg for the allanite from Franklin. The Mössbauer spectra show a decrease in the Fe2+ doublet intensity with increasing absorbed α-dose. We also observe an increase in the line widths of the Fe2+ and Fe3+ doublets with increasing absorbed α-dose.

DOI: 10.12693/APhysPolA.114.1683 PACS numbers: 33.45.+x, 61.82.Fd, 64.60.My, 76.80.+y