Advances in multi-elementary analysis of fluid or solid micro-crystalline inclusions (12

International audienceX-Ray-based analytical methods can be applied in an absolute fashion, provided that matrix effects are calculated and that parameters related to instrumental factors are controlled (Newbury, 1986). When EPMA (Electron Probe Micro Analysis) was conceived at the end of the 60's, this potentiality was abandoned, as the instrument works in a relative fashion, by comparison with standards. At the end of the 70's and in the 80's, PIXE (Proton Induced X-Ray Emission) by contrast was applied in a way that preserved the possibility of an absolute application: the computer programs developed to interpret PIXE spectra calculate matrix effects and also integrate instrumental factors (e.g., Maxwell et al., 1989). In spite of this advantage, and also despite the fact that PIXE application extends to trace element analysis, the development of PIXE in the scientific community was sluggish, in deep contrast with the widespread applications of EPMA. In the field of Earth Sciences particularly, EPMA was recognized by the Mineralogical Society of America to have had 'a revolutionary, profound impact on mineralogy and petrology'. In the same time, PIXE applications remained mainly restricted to trace element analysis, and the potential accuracy of the method was never clearly realized. A first aim of this presentation is to show that, using a simple standardization procedure, the multi-elementary absolute capability of PIXE can be revealed. This in turn changes PIXE into a tool of quantitative mineralogy and trace element geochemistry. We then show that, by coupling PIXE to PIGE (Proton Induced Gamma Ray Emission) and RBS (Rutherford Back Scattering) spectrometries, the Nuclear Microprobe becomes a tool for quantitative mineralogy s.l. and geochemistry, i.e., an instrument to analyze all major to trace elements from Li to U in minerals and their inclusions. In the second part of the presentation, we illustrate the capability of µ-PIXE to analyze in situ individual fluid inclusions that have been carefully localized in space and time. The Hercynian French Massif Central and its sedimentary eastern margin are part of a large European Carbonic Province, which hosts numerous deep CO2 reservoirs and carbonic springs (Blavoux, Dazy, 1990). Carbonic fluids are present at all stages of the long-lived evolution of this crustal segment, from deep metamorphic fluids involved in a thrusting event at 340 M.a to mantle-derived volcanic CO2 related to Neogene volcanism. In order to characterize the main aquo-carbonic fluid reservoirs through time in this crustal segment, we present preliminary data on the trace element content of aquo-carbonic inclusions trapped in the schists at peak and retrograde metamorphic conditions, and compare them to contemporaneous granite-related fluid inclusion

On the detachment of Si ingots from SiO2 crucibles.

International audienceIn a directional solidification furnace, ingots of silicon are contained in a silica crucible covered with a silicon nitride (Si3N4) powder layer. During the crystallization of the ingot, the layer may suffer various behaviors. When properly applied, it can efficiently act as a mechanical shunt between the Si and the silica wall. However, filling of the crucible with silicon pieces can also scratch locally the layer, resulting in deleterious adhesion between ingot and crucible. The layer can also be too thin, or insufficiently pyrolyzed, so that the Si interacts with the silica crucible. An extended simulation is carried out; taking into account the thermo-elastic stresses induced by the difference in thermal expansion coefficients of the crucible and ingot materials that are attached On small areas. The model compares the remaining elastic energy to the adhesion energy between the silicon and the crucible, in order to predict the temperature at which the Si detaches from the crucible in case of sticking. Two configurations are compared in terms of amount or stresses and extent of the ingot volume likely to be impacted by dislocation generation. (C) 2013 Published by Elsevier B.V

Rare metal sequestration and mobility in mineralized black shales from the Zunyi region, South China

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NRA analyses of N and C in hydromuscovite aggregates from a 3.5 Ga chert from Kittys Gap, Pilbara, Australia

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Biogenic origin of intergrown Mo-sulphide- and carbonaceous matter in Lower Cambrian black shales (Zunyi Formation, southern China)

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Hydrogen incorporation into high temperature protonic conductors : nuclear microprobe microanalysis by means of H(p,p,) H scattering

International audienceProtonic conductivity of some solid state materials at an intermediate temperature range (400–600 °C), referred as high temperature protonic conductor (HTPC), suggests their application as electrolytes in electrochemical cells, batteries, sensors, etc. Among them, some perovskites can be protonic and electronic conductors. Several obstacles remain to achieve the full potential of these ceramic membranes, among them the lack of measurement techniques and of an unambiguous model for conductivity. A precise understanding of the transport mechanisms requires local profiling of hydrogen concentrations within the microstructure of the ceramic. We have used the nuclear microprobe of the Laboratoire Pierre SÜE to investigate quantitatively the spatial distribution of hydrogen after water heat treatment of textured perovskites, SrCe0.9Y0.1O3−δ and Sr3Ca1+xNb2−xO9−δ, x = 0.18, synthesized according to a melt-process developed at NASA GRC. A not very common method has been developed for hydrogen measurements in thin samples, 1H(p, p)1H elastic recoil coincidence spectrometry (ERCS). Early experiments have evidenced hydrogen concentration enhancement within grain boundaries

The influence of laser power and repetition rate on oxygen and nitrogen insertion into titanium using pulsed Nd:YAG laser irradiation

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