Temperature dependence of Kr ion-induced amorphization of mica minerals

Wang, L.M; Wang, S.X; Gong, Weiliang; Ewing, Rodney C.

doi:10.1016/s0168-583x(98)00144-x

Cited by 24 publications

(8 citation statements)

References 19 publications

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“…The Monte-Carlo based simulation software, the Stopping and Range of Ions in Matter (SRIM) (Ziegler 2013) was used to calculate necessary ion fluences to achieve sequentially increasing ion doses across the biotite samples, up to a maximum ion density normalized dose of 6.77 dpa (average across dose gradient = 0.28 dpa; see Tables 1 and 2). The critical amorphization threshold for a mica structure has been calculated to be 0.15 dpa (Wang et al 1998), however the X-ray diffraction (XRD) study here demonstrates that some original structure is retained at doses far higher than this, despite extensive point defect densities throughout the former lattice. SRIM modeling was used to determine that a relatively light incident ion such as helium entering a mica sample at 5 MeV creates on average 225 knock-on displacements (Frenkel defects) per ion track in the sample.…”

Section: Ion Dose and Radiation Damage Modelingmentioning

confidence: 61%

Radiation damage in biotite mica by accelerated α-particles: A synchrotron microfocus X-ray diffraction and X-ray absorption spectroscopy studyk

Bower

Pearce

Smith³

et al. 2016

American Mineralogist

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A critical radiation damage assessment of the materials that will be present in a Geological Disposal Facility (GDF) for radioactive waste is a priority for building a safety case. Detailed analysis of the effects of high-energy a-particle damage in phyllosilicates such as mica is a necessity, as these are model structures for both the clay-based backfill material and the highly sorbent components of a crystalline host rock. The a-radiation stability of biotite mica [general formula: K(Mg,Fe) 3 (Al,Si 3 O 10) (F,OH) 2 ] has been investigated using the 5 MV tandem pelletron at the University of Manchester's Dalton Cumbrian Facility (DCF) and both the microfocus spectroscopy (I18) and core X-ray absorption spectroscopy (B18) beamlines at Diamond Light Source (U.K.). Microfocus X-ray diffraction mapping has demonstrated extensive structural aberrations in the mica resulting from controlled exposure to the focused 4 He 2+ ion (a-particle) beam. Delivered doses were comparable to a-particle fluences expected in the highly active, near-field of a GDF. At doses up to 6.77 displacements per atom (dpa) in the region of highest particle fluence, biotite mica displays a heterogeneous structural response to irradiation on a micrometer scale, with sequential dilation and contraction of regions of the structure perpendicular to the sheets, as well as a general overall contraction of the phyllosilicate layer spacing. At the peak of ion fluence, the structure collapses under a high point defect density and amorphous areas are pervasive among altered domains of the original lattice. Such structural alterations are likely to affect the material's capacity to sorb and retain escaped radionuclides over long timescales; increased edge site availability may favor increased sorption while interlayer uptake will likely be reduced due to collapse. Radiation-induced reduction of structural iron at the region of highest structural damage across an a-particle's track has been demonstrated by Fe K-edge X-ray absorption near edge spectroscopy (XANES) and local structural disorder has been confirmed by analysis of both potassium K-edge XANES and Fe K-edge extended X-ray absorption fine structure analysis. An infrared absorption study of deformations in the OHstretching region, along with electron probe microanalysis complements the synchrotron data presented here.

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Section: Ion Dose and Radiation Damage Modelingmentioning

confidence: 61%

Radiation damage in biotite mica by accelerated α-particles: A synchrotron microfocus X-ray diffraction and X-ray absorption spectroscopy studyk

Bower

Pearce

Smith³

et al. 2016

American Mineralogist

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“…There is a generally accepted threshold value of displacements per atom for a given crystal structure before it is considered amorphous; in the case of a biotite mica structure, this value is 0.15 dpa. 9 The relationship between particle flux and dpa is…”

mentioning

confidence: 99%

Note: Establishing α-particle radiation damage experiments using the Dalton Cumbrian Facility’s 5 MV tandem pelletron

Bower

Smith

Pattrick

et al. 2015

Review of Scientific Instruments

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Evaluating the radiation stability of mineral phases is a vital research challenge when assessing the performance of the materials employed in a Geological Disposal Facility for radioactive waste. This report outlines the setup and methodology for efficiently allowing the determination of the dose dependence of damage to a mineral from a single ion irradiated sample. The technique has been deployed using the Dalton Cumbrian Facility's 5 MV tandem pelletron to irradiate a suite of minerals with a controlled α-particle ((4)He(2+)) beam. Such minerals are proxies for near-field clay based buffer material surrounding radioactive canisters, as well as the sorbent components of the host rock.

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“…To produce areas with different degrees of damage, 14 irradiation experiments under identical conditions but at different temperatures were done. In doing this, we used the well-known fact that the amorphization rate of ionbeam irradiated solids depends strongly on temperature (e.g., Wang et al 1998aWang et al , 1998b. To avoid any damage annealing upon re-heating, experiments were done beginning with the highest temperature (225; 200, between 180 and 100 °C at 10° steps; 80; 34; 23 °C).…”

Section: Samples and Experimental Detailsmentioning

confidence: 99%

Effects of irradiation damage on the back-scattering of electrons: Silicon-implanted silicon

Nasdala

Kronz

Grambole

et al. 2007

American Mineralogist

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Radiation damage in a (initially crystalline) silicon wafer was generated by microbeam ion implantation with 600 keV Si + ions (fl uence 5 × 10 14 ions/cm 2 ). To produce micro-areas with different degrees of damage, 14 implantations at different temperatures (between 23 and 225 °C) were done. The structural state of irradiated areas was characterized using Raman spectroscopy and electron back-scatter diffraction. All irradiated areas showed strong structural damage in surfi cial regions (estimated depth <1 μm), and at implant substrate temperatures of below 130 °C, the treatment caused complete amorphization. Back-scattered electron (BSE) image intensities correlate with the degree of irradiation damage; all irradiated areas were higher in BSE than the surrounding host. Because there were no variations in the chemical composition and, with that, no Z contrast in our sample, this observation again supports the hypothesis that structural radiation damage may strongly affect BSE images of solids.

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Temperature dependence of Kr ion-induced amorphization of mica minerals

Cited by 24 publications

References 19 publications

Radiation damage in biotite mica by accelerated α-particles: A synchrotron microfocus X-ray diffraction and X-ray absorption spectroscopy studyk

Radiation damage in biotite mica by accelerated α-particles: A synchrotron microfocus X-ray diffraction and X-ray absorption spectroscopy studyk

Note: Establishing α-particle radiation damage experiments using the Dalton Cumbrian Facility’s 5 MV tandem pelletron

Effects of irradiation damage on the back-scattering of electrons: Silicon-implanted silicon

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