Alpha particle haloes in chlorite and cordierite

Nasdala, Lutz; Wildner, Manfred; Wirth, Richard; Groschopf, Nora; Pal, Dipak C.; Möller, Andreas

doi:10.1007/s00710-005-0104-6

Cited by 40 publications

(33 citation statements)

References 67 publications

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“…Consistent with other studies(Nasdala et al, 2006;Pal, 2004;Pattrick et al, 2013), no significant chemical differences were observed; however, calculating all iron as Fe 2+ and accounting for cation excesses above 15 per formula unit ( p.f.u. ), relative Fe 2+ /Fe 3+ ratios were estimated and show a slight decrease (0.03 atoms p.f.u.)…”

supporting

confidence: 92%

“…The exact mechanism of discolouration (ionization vs. structural defects) across radiohalos is still a subject of debate (Nasdala et al, 2006). This study finds that discolouration and structural damage do not always directly coincide; it is possible that colour-inducing radiation 'damage' may be more a product of ionization mechanisms, whilst point defects alone do not directly produce a pattern of discolouration.…”

Section: Discussionmentioning

confidence: 86%

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Radiation damage from long-term alpha particle bombardment of silicates – a microfocus XRD and Fe K-edge XANES study

et al. 2015

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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. Fe 3+ → Fe 2+ 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 Fe 3+ reducing electrons. Across all samples, high point defect densities and minor lattice aberrations are apparent adjacent to the radioactive inclusion, demonstrated by micro-XRD.

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supporting

confidence: 92%

Section: Discussionmentioning

confidence: 86%

Radiation damage from long-term alpha particle bombardment of silicates – a microfocus XRD and Fe K-edge XANES study

et al. 2015

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“…6c). The damaged/amorphised zone is interpreted as alpha-recoil halo, [22,23] i.e. the damage in the apatite was generated mainly by recoils of heavy nuclei originating from the high Th content in the neighbouring veinlet material.…”

Section: Transmission Electron Microscopymentioning

confidence: 99%

Phase Decomposition upon Alteration of Radiation-Damaged Monazite–(Ce) from Moss, Østfold, Norway

Nasdala

Ruschel²,

Rhede³

et al. 2010

Chimia

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The internal textures of crystals of moderately radiation-damaged monazite-(Ce) from Moss, Norway, indicate heavy, secondary chemical alteration. In fact, the cm-sized specimens are no longer mono-mineral monazite but rather a composite consisting of monazite-(Ce) and apatite pervaded by several generations of fractures filled with sulphides and a phase rich in Th, Y, and Si. This composite is virtually a 'pseudomorph' after primary euhedral monazite crystals whose faces are still well preserved. The chemical alteration has resulted in major reworking and decomposition of the primary crystals, with potentially uncontrolled elemental changes, including extensive release of Th from the primary monazite and local redeposition of radionuclides in fracture fillings. This seems to question the general alteration-resistance of orthophosphate phases in a low-temperature, 'wet' environment, and hence their suitability as potential host ceramics for the long-term immobilisation of radioactive waste.

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“…These techniques allow us to determine the density of various types of lattice defects produced by natural radiation over geological timescale. Recent scientific interest in radiation effects on minerals focus not only on such geological applications, but also geoscientific and planetary scientific applications, e.g., observation of pleochroic halo in quartz and feldspar generated by natural radiation from the disintegration of radioactive elements (Nasdala et al, 2006), clarification of release process of Na atoms from plagioclase on the surface of the Moon and Mercury into the exospheres due to space weathering (Sprague et al, 2002;Wurz and Lammer, 2003;Lowitzer et al, 2008) and detection of food irradiation (Soika and Delincée, 2000). These radiation effects on minerals, caused mainly by ions, protons and electrons as well as α particles, are seen from the grain surface to a depth of several tens to hundreds of micrometers.…”

Section: Introductionmentioning

confidence: 99%

Response of cathodoluminescence of alkali feldspar to He+ ion implantation and electron irradiation

et al. 2013

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Cathodoluminescence (CL) of minerals such as quartz and zircon has been extensively studied to be used as an indicator for geodosimetry and geochronometry. There are, however, very few investigations on CL of other rock-forming minerals such as feldspars, regardless of their great scientific interest. This study has sought to clarify the effect of He + ion implantation and electron irradiation on luminescent emissions by acquiring CL spectra from various types of feldspars including anorthoclase, amazonite and adularia. CL intensities of UV and blue emissions, assigned to Pb 2+ and Ti 4+ impurity centers respectively, decrease with an increase in radiation dose of He + ion implantation and electron irradiation time. This may be due to decrease in the luminescence efficiencies by a change of the activation energy or a conversion of the emission center to a non-luminescent center due to an alteration of the energy state. Also, CL spectroscopy of the alkali feldspar revealed an increase in the blue and yellow emission intensity assigned to Al-O − -Al/Ti defect and radiation-induced defect centers with the radiation dose and the electron irradiation time. Taken together these results indicate that CL signal should be used for estimation of the α and β radiation doses from natural radionuclides that alkali feldspars have experienced.

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Alpha particle haloes in chlorite and cordierite

Cited by 40 publications

References 67 publications

Radiation damage from long-term alpha particle bombardment of silicates – a microfocus XRD and Fe K-edge XANES study

Radiation damage from long-term alpha particle bombardment of silicates – a microfocus XRD and Fe K-edge XANES study

Phase Decomposition upon Alteration of Radiation-Damaged Monazite–(Ce) from Moss, Østfold, Norway

Response of cathodoluminescence of alkali feldspar to He+ ion implantation and electron irradiation

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