A new method for studying leached glasses: Analytical electron microscopy on ultramicrotomic thin sections

Ehret, G.; Crovisier, J. L.; Eberhart, Jean-Pierre

doi:10.1016/0022-3093(86)90476-x

Cited by 32 publications

(10 citation statements)

References 6 publications

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“…Il apparaît que les éléments de transition et les métaux lourds sont en concentrations importantes dans la phase de manganèse. Cox (1996); verres de REFIOM: Colombel (1996); Le Forestier (1996); verres quaternaires Si-Na-Ca-P: Ehret et al (1986); verres de confinement des déchets nucléaires: Nogues (1984); Advocat (1991); Valle (2000)]. L'ensemble de ces observations indique que les phases phosphatées sont caractéristiques des produits secondaires de l'altération de ces verres, quelle que soit leur composition chimique globale.…”

Section: Discussionunclassified

Cristallochimie des produits d'altération des vitraux médiévaux: application au vieillissement des déchets vitrifiés

Sterpenich

2002

Bulletin of Engineering Geology and the Environment

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Les vitraux médiévaux, altérés à même les verrières ou exhumés lors de fouilles archéologiques, fournissent un excellent analogue pour suivre le comportement à long terme de déchets vitrifiés altérés en conditions naturelles. Ils permettent en effet d'étudier l'influence des conditions d'altération et de la composition du verre sur sa dissolution, et de déterminer les cinétiques de dissolution des élé-ments piégés dans le verre sur des périodes de plus d'un millénaire. Ce travail montre de plus que la dissolution des verres silico-calciques et alcalins est incongruente et que la minéralogie des pellicules d'altération joue un rôle primordial quant au comportement à long terme des déchets vitrifiés, puisque même si le verre s'altère, les produits secondaires peuvent, dans certains cas, piéger la majorité des éléments polluants.Abstract One of the major problems of modern society is to render inoffensive ultimate wastes produced by municipal, industrial or nuclear activity. These ultimate wastes contain high amounts of toxic elements and have to be stabilised before storage. Among the actual solidification-stabilisation processes, vitrification offers many advantages, such as a reduction of volume, no porosity and good chemical durability. However, before using silicate glasses to stabilise ultimate wastes, it is necessary to ensure the long-term behaviour of these materials and to study their solubility and the possible dispersion of polluting elements into the biosphere. Although many leaching experiments have been carried out, knowledge of the behaviour of vitrified wastes weathered over periods of 100 to 10,000 years remains sparse. Previous work (Sterpenich et Libourel 2001) has shown that medieval stained-glass windows provide a valuable opportunity to study the alteration and long-term behaviour of vitrified wastes under natural conditions of weathering. This study allowed the quantification of the influence of conditions of alteration and of glass composition on dissolution kinetics through the calculation of mean dissolution rates of toxic elements over periods of time of up to one millennium. However, the mineralogy and the chemistry of altered-layer stained glasses are complex. An essential second step is the study of the crystal chemistry of pollutants in order to determine the long-term stability of the phases containing them and thus to ensure the long-term containment of potentially toxic elements.This work focuses on the identification of mineral phases formed through alteration of medieval stained glasses, either on windows or buried in the soil. Medieval stained-glass windows allow the study of the behaviour of a glass submitted to different alteration conditions over periods of more than one millennium. Due to their chemical complexity, medieval stained glasses permit the quantification of release rates of elements, in particular pollutants belonging to the vitreous silicate matrix. Medieval stained glasses altered on windows by meteoric waters develop an altered layer made of a hydrated silica ...

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Section: Discussionunclassified

Cristallochimie des produits d'altération des vitraux médiévaux: application au vieillissement des déchets vitrifiés

Sterpenich

2002

Bulletin of Engineering Geology and the Environment

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“…Ultramicrotome cross-section of altered glass 2 powder prepared according to the technique by Ehret et al [16] were observed using a transmission electron microscope Philips CM 120 (TEM).…”

Section: Characterizationsmentioning

confidence: 99%

Morphological evolution of alteration layers formed during nuclear glass alteration: new evidence of a gel as a diffusive barrier

Rébiscoul¹,

Lee²,

Rieutord³

et al. 2004

Journal of Nuclear Materials

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“…For electron microdiffraction and chemical composition, thin sections, a few hundred of angstroms (,~) in thickness, were obtained by pouring an epoxy resin onto the altered surface under vacuum and pulling off the resin after polymerization. The sample is embedded once more and sliced by the ultramicrotome (Ehret et al 1986). …”

Section: Electron Microscopymentioning

confidence: 99%

Formation of Hydrotalcite-like Compounds During R7T7 Nuclear Waste Glass and Basaltic Glass Alteration

Abdelouas

1994

Clays and clay miner.

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Abstract--Alteration experiments have been performed using RTT7 and synthetic basaltic glasses in MgC1E-CaClz salt solution at 190~ The duration of experiments ranged from 0.25 to 463 days. The alteration products were studied by Scanning Electron Microscope (SEM), Scanning Transmission Electron Microscope (STEM), X-ray diffraction (XRD) and Electron Spectrometry for Chemical Analysis (ESCA).For both glasses, the early alteration product is a hydrotalcite-like compound [MgrAlzCO3(OH)~6' 4H20] in which HPO42 , SO42-and C1-substitutes for CO32-. The measured basal spacing is 7.68 A for the hydrotalcite formed from R7T7 glass and 7.62 ~ for the hydrotalcite formed from basaltic glass which reflect the high A1/A1 + Mg ratios x (0.34 -< x -< 0.46). The chemical microanalyses show that the hydrotalcite is subsequently covered by a silica-rich gel which evolves into saponite after a few months. These results support the use of basaltic glasses alteration patterns in Mg-rich solution, to understand the long-term behavior of R7T7 nuclear waste glass.

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A new method for studying leached glasses: Analytical electron microscopy on ultramicrotomic thin sections

Cited by 32 publications

References 6 publications

Cristallochimie des produits d'altération des vitraux médiévaux: application au vieillissement des déchets vitrifiés

Cristallochimie des produits d'altération des vitraux médiévaux: application au vieillissement des déchets vitrifiés

Morphological evolution of alteration layers formed during nuclear glass alteration: new evidence of a gel as a diffusive barrier

Formation of Hydrotalcite-like Compounds During R7T7 Nuclear Waste Glass and Basaltic Glass Alteration

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