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Radiation damage from long-term alpha particle bombardment of silicates – a microfocus XRD and Fe K-edge XANES study
DOI:
10.1180/minmag.2015.079.6.20
Authors:
W. R.
Bower
(University of Manchester)
,
C. I.
Pearce
(University of Manchester)
,
G. T. R.
Droop
(University of Manchester)
,
J. F. W.
Mosselmans
(Diamond Light Source)
,
K.
Geraki
(Diamond Light Source)
,
R. A. D
Pattrick
(University of Manchester)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Mineralogical Magazine
, VOL 79 (6)
, PAGES 1455 - 1466
State:
Published (Approved)
Published:
December 2015
Diamond Proposal Number(s):
6208
,
9044

Abstract: A detailed understanding of the response of mineral phases to the radiation fields experienced in a geological disposal facility (GDF) is currently poorly constrained. Prolongued ion irradiation has the potential to affect both the physical integrity and oxidation state of materials and therefore may alter a structure's ability to react with radionuclides. Radiohalos (spheres of radiation damage in minerals surrounding radioactive (α-emitting) inclusions) provide useful analogues for studying long term α-particle damage accumulation. In this study, silicate minerals adjacent to Th- and U-rich monazite and zircon were probed for redox changes and long/short range disorder using microfocus X-ray absorption spectroscopy (XAS) and high resolution X-ray diffraction (XRD) at Beamline I18, Diamond Light Source. Fe3+→ Fe2+ reduction has been demonstrated in an amphibole sample containing structural OH− groups – a trend not observed in anhydrous phases such as garnet. Coincident with the findings of Pattrick et al. (2013), the radiolytic breakdown of OH− groups is postulated to liberate Fe3+ reducing electrons. Across all samples, high point defect densities and minor lattice aberrations are apparent adjacent to the radioactive inclusion, demonstrated by micro-XRD.
Journal Keywords: radiation damage; alpha particle; silicates; Fe K-edge; XRD; XANES
Subject Areas:
Environment,
Materials,
Earth Science
Instruments:
I18-Microfocus Spectroscopy