EELS analysis of SiC crystals under hydrogen and helium dual-ion beam irradiation

Hojou, K.; Furuno, S.; Kushita, Kouhei N.; Sasajima, N.; Izui, K.

doi:10.1016/s0168-583x(98)00181-5

Cited by 31 publications

(19 citation statements)

References 13 publications

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“…The substrate spectra have relatively narrow volume plasmon peaks, typical of crystalline silicates, with weak surface plasmons between 8 eV and 12 eV originating from the upper and lower surfaces of the thin specimen. The volume plasmon peaks from the rims are significantly broader and are often shifted to a lower energy because surface plasmon contributions are greater due to irradiation-induced atomic-bond disruption, the presence of vesicles, and nanoporosity (12,18,19). Water IT, EG, and H-K features are observed in some vesicles in H + -irradiated rims but not in He + -irradiated rims, where, instead, the He-K core scattering edge at ∼22 eV is observed in some vesicles (Fig.…”

Section: Significancementioning

confidence: 99%

“…We used valence electron energy-loss spectroscopy (VEELS) because its ability to detect water in situ at the nanoscale has been demonstrated in aqueous liquids, biomaterials, and ices (15)(16)(17). VEELS characterizes the low-loss region of the energy loss spectrum (0-50 eV), where features due to plasmons, valence band transitions, −OH, and H 2 O can be observed (12,(15)(16)(17)(18)(19) …”

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confidence: 99%

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Detection of solar wind-produced water in irradiated rims on silicate minerals

Bradley

Ishii

Gillis-Davis

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The solar wind (SW), composed of predominantly ∼1-keV H + ions, produces amorphous rims up to ∼150 nm thick on the surfaces of minerals exposed in space. Silicates with amorphous rims are observed on interplanetary dust particles and on lunar and asteroid soil regolith grains. Implanted H + may react with oxygen in the minerals to form trace amounts of hydroxyl (−OH) and/or water (H 2 O). Previous studies have detected hydroxyl in lunar soils, but its chemical state, physical location in the soils, and source(s) are debated. If −OH or H 2 O is generated in rims on silicate grains, there are important implications for the origins of water in the solar system and other astrophysical environments. By exploiting the high spatial resolution of transmission electron microscopy and valence electron energy-loss spectroscopy, we detect water sealed in vesicles within amorphous rims produced by SW irradiation of silicate mineral grains on the exterior surfaces of interplanetary dust particles. Our findings establish that water is a byproduct of SW space weathering. We conclude, on the basis of the pervasiveness of the SW and silicate materials, that the production of radiolytic SW water on airless bodies is a ubiquitous process throughout the solar system. solar wind radiolysis | prebiotic water | cosmic dust | astrobiology | aberration-corrected scanning transmission electron microscopy T here are two principal space weathering processes, solar wind (SW) ion irradiation and micrometeorite impacts, that produce rims on exposed mineral surfaces (1). Our focus here is on SW irradiation because of its possible connection to the production of water and hydroxyl radicals (2-5). Space-weathered rim thicknesses vary with the densities of implanted solar flare (SF) tracks, and track densities depend on the exposure ages of individual interplanetary dust particles (IDPs) in space. On lunar soil grains and grains on surfaces of IDPs, rims are typically 75-150 nm thick with SF track densities of 10 10 -10 11 cm −2 that are consistent with 10 4 -to 10 5 -y SW exposure ages (6, 7) ( Fig. 1 B-D). Rims on asteroid Itokawa regolith grains are 30-60 nm thick with SF track densities of 5 × 10 9 cm −2 that are consistent with ∼10 3 -y exposure ages (8) (Origins and Properties of Rims on IDPs, Asteroid Itokawa, and Lunar Soil Grains). This correlation between amorphous rim thicknesses and SF track densities indicates that SW irradiation is the primary mechanism for amorphous rim formation. We examine rims on surface grains in IDPs because they are solely due to SW irradiation, whereas rims on lunar soil grains are due to SW irradiation, impact vapor deposition, or a combination of both (9), and remote observations suggest that if water is indeed produced in rims on lunar soil grains, it is not efficiently retained (10). Typical 5-to 25-μm diameter chondritic porous (CP) IDPs are low-density aggregates of predominantly submicrometer-sized grains, and they are collected in the stratosphere (11) (Fig. 1 A-D and Origins of CP IDPs). Chemical ana...

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Section: Significancementioning

confidence: 99%

mentioning

confidence: 99%

Detection of solar wind-produced water in irradiated rims on silicate minerals

Bradley

Ishii

Gillis-Davis

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…4. It is known that there are a number of excitation levels of hydrogen atom in SiC in this energy region, 11-14 eV, 14,15) and hence it is considered that the bright contrast should correspond to hydrogen distributions, or direct imaging of hydrogen. Since the bulk plasmon peaks of the surface layer and the deep region are located at 21.0 eV and 19.3 eV respectively, the top layer more contributes to the image intensity in (c).…”

Section: (A)-(d)mentioning

confidence: 99%

Cross Sectional TEM Observation of Gas-Ion-Irradiation Induced Surface Blisters and Their Precursors in SiC

2003

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Cross sectional structures of surface blisters and their precursors in SiC formed by H þ , D þ and He þ irradiation were examined with transmission electron microscopy and electron energy-loss spectroscopy. The substructures of the H þ -and D þ -irradiated samples showed similar features, and experimental results suggested that H 2 and CH 4 bubbles nucleated after H(D)-trapping sites were saturated and the first nucleated bubbles grew by absorbing the gas molecules formed by further ion irradiation, followed by lift-up of the surface layer with increasing the internal pressure. The implanted hydrogen atoms other than those forming bubbles were scattered in atomic form, preferably bonded to carbon atoms. On the other hand the substructure of He þ irradiated sample was very similar to that of metals and other materials irradiated by He þ , and it is considered that the formation mechanism of He-blister is common for most materials.

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“…[4][5][6] The solubility of hydrogen in SiC is also very low. Hydrogen is trapped at both Si-and C-sites by the displacement damage, where it forms C-H or Si-H. 7) Thermal desorption spectrometry has shown that the mobility of hydrogen in SiC increases above 1073 K. 8) Therefore, hydrogen could potentially enhance cavity formation at temperatures of 1073 K and above, which corresponds to the operating temperature range of a fusion reactor using a SiC/SiC composite. The effects of the simultaneous production of displacement damage, helium and hydrogen in SiC must be known to predict the material's lifetime in the fusion reactor environment.…”

Section: )mentioning

confidence: 99%

Cavity Formation in a SiC/SiC Composite under Simultaneous Irradiation of Hydrogen, Helium and Silicon Ions

Miwa

Hasegawa

Taguchi³

et al. 2005

Mater. Trans.

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Cavity formation was investigated in a SiC/SiC composite under multi-ion beam irradiation up to 10 dpa at 1073 K, 1273 K and 1573 K by transmission electron microscopy. The cavity formation behavior of each component of the composite was dependent on the component's grain structure, the helium and/or hydrogen implantation mode, and irradiation temperature. It was found that helium rather than hydrogen is likely to enhance cavity formation or cavity swelling. The contributions of helium and hydrogen to cavity formation in the composite components are discussed in detail.

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EELS analysis of SiC crystals under hydrogen and helium dual-ion beam irradiation

Cited by 31 publications

References 13 publications

Detection of solar wind-produced water in irradiated rims on silicate minerals

Detection of solar wind-produced water in irradiated rims on silicate minerals

Cross Sectional TEM Observation of Gas-Ion-Irradiation Induced Surface Blisters and Their Precursors in SiC

Cavity Formation in a SiC/SiC Composite under Simultaneous Irradiation of Hydrogen, Helium and Silicon Ions

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