Electron irradiation damage in quartz, SiO2

Martin, B.; Flörke, O. W.; Kainka, Eva; Wirth, Richard

doi:10.1007/bf00202027

Cited by 22 publications

(6 citation statements)

References 27 publications

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“…Sanchez‐Navas et al ., ). Therefore, we interpret these electron‐lucent structures are likely caused by electron beam damage, also in analogy to electron beam damaged quartz that occurs as strain contrast centres (Carter & Kohlstedt, ; Martin et al ., ).…”

Section: Resultsmentioning

confidence: 97%

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India

et al. 2015

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Stromatolites composed of apatite occur in post-Lomagundi-Jatuli successions (late Palaeoproterozoic) and suggest the emergence of novel types of biomineralization at that time. The microscopic and nanoscopic petrology of organic matter in stromatolitic phosphorites might provide insights into the suite of diagenetic processes that formed these types of stromatolites. Correlated geochemical micro-analyses of the organic matter could also yield molecular, elemental and isotopic compositions and thus insights into the role of specific micro-organisms among these communities. Here, we report on the occurrence of nanoscopic disseminated organic matter in the Palaeoproterozoic stromatolitic phosphorite from the Aravalli Supergroup of north-west India. Organic petrography by micro-Raman and Transmission Electron Microscopy demonstrates syngeneity of the organic matter. Total organic carbon contents of these stromatolitic phosphorite columns are between 0.05 and 3.0 wt% and have a large range of δ(13) Corg values with an average of -18.5‰ (1σ = 4.5‰). δ(15) N values of decarbonated rock powders are between -1.2 and +2.7‰. These isotopic compositions point to the important role of biological N2 -fixation and CO2 -fixation by the pentose phosphate pathway consistent with a population of cyanobacteria. Microscopic spheroidal grains of apatite (MSGA) occur in association with calcite microspar in microbial mats from stromatolite columns and with chert in the core of diagenetic apatite rosettes. Organic matter extracted from the stromatolitic phosphorites contains a range of molecular functional group (e.g. carboxylic acid, alcohol, and aliphatic hydrocarbons) as well as nitrile and nitro groups as determined from C- and N-XANES spectra. The presence of organic nitrogen was independently confirmed by a CN(-) peak detected by ToF-SIMS. Nanoscale petrography and geochemistry allow for a refinement of the formation model for the accretion and phototrophic growth of stromatolites. The original microbial biomass is inferred to have been dominated by cyanobacteria, which might be an important contributor of organic matter in shallow-marine phosphorites.

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Section: Resultsmentioning

confidence: 97%

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India

et al. 2015

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“…12 and 13). It appears, for both tridymite and cristobalite, that irradiated electrons penetrate into the structure at least up to several micrometers with interactions between the electron beam and the solid, whereas electron-irradiation damage of quartz was estimated to occur to a depth of several hundred nanometers by TEM (Martin et al 1996). CL excitation is detected near the limit of beam penetration due to efficient generation of CL with relatively low energy compared with other signals such as X-ray, secondary, and back-scattered electrons (Marshall 1988).…”

Section: Micro-raman Measurementsmentioning

confidence: 99%

“…Electron irradiation with a high radiation dose can easily alter the crystalline state of tridymite and cristobalite. It is also known that the crystal structure of these minerals can be changed by X-ray irradiation (Ashworth 1988;Hobbs 1994;Withers et al 1994;Martin et al 1996). The electron beam used in transmission electron microscopy (TEM) observation, where a higher-electron energy is required as current density than that used in scanning electron microscopy (SEM), causes an instantaneous phase transition from cristobalite and tridymite to amorphous SiO 2 .…”

mentioning

confidence: 98%

Cathodoluminescence characterization of tridymite and cristobalite: Effects of electron irradiation and sample temperature

Kayama

Nishido

Ninagawa

2009

American Mineralogist

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Cathodoluminescence (CL) spectra of tridymite and cristobalite have broad peaks around 430 and 400 nm, respectively, both of which can be assigned to the [AlO 4 /M + ] 0 defect. The CL intensities of these spectral peaks in the blue region decrease with prolonged exposure to electron irradiation, similar to the short-lived luminescence observed in quartz, although quartz shows a lower decrease in CL intensity compared to these minerals. Cristobalite has a higher CL intensity reduction rate during irradiation than does tridymite. Irradiation of these minerals at low temperatures results in a more rapid decay of CL emission, whereas that of quartz shows no apparent change in the rate of CL emission at similar temperatures. Confocal micro-Raman spectroscopy of the electron irradiated surface of these minerals reveals the amorphization caused by the interaction of the electron beam with the surface layer to a depth of several micrometers. This suggests that such structural destruction diminishes the activity of CL emission centers related to the [AlO 4 /M + ] 0 defects by migration of monovalent cations associated with exchanged Al in the tetrahedral sites. Both samples present a considerable reduction of their CL intensities at higher temperature, suggesting a temperature quenching phenomenon. The activation energy in the quenching process was evaluated by a least-squares fitting of the Arrhenius plots, assuming the Mott-Seitz model. The result implies that the energy of non-radiative transition in this process might be transferred to lattice vibrations as phonons in two different manners. This might be related to different irradiation responses of the CL with a change in sample temperature.

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“…It is well known that ion beam thinning produces a thin amorphous area right at the edge of the specimen, due to the destruction of the lattice by ion bombardment resulting in displacement damage of the crystal [Hobbs and Pascucci, 1980;Carter and Kohlstedt, 1981;Inui et ai., 1990;Martin et al, 1996]. Ion beam thinning can never produce two different glass compositions along an interface of the same kind like an olivine grain boundary.…”

Section: Why Are the Amorphous Intergranular Layers Former Melt Films?mentioning

confidence: 86%

Physics and Chemistry of Partially Molten Rocks

Bagdassarov¹,

Laporte²,

Thompson³

2000

Petrology and Structural Geology

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Cover illustration: Secondary electron photographs of fracture surfaces of quartzites synthesized in the presence of small volume fractions of various fluids. a Quartzite containing"'0.2 voI. % of hydrous granitic melt (8= 14°; P-T-t conditions are 900 °C -lGPa-159 hr; from Laporte et al., 1997, Fig. 7): melt forms an interconnected network of grain-edge channels (edges along which the glass has been destroyed during sample preparation appear rounded).

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Electron irradiation damage in quartz, SiO2

Cited by 22 publications

References 27 publications

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India

Cathodoluminescence characterization of tridymite and cristobalite: Effects of electron irradiation and sample temperature

Physics and Chemistry of Partially Molten Rocks

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