Quantitative X-ray Mapping Research Articles

Quantitative X-ray Maps Analaysis of Composition and Microstructure of Permian High-Temperature Relicts in Acidic Rocks from the Sesia-Lanzo Zone Eclogitic Continental Crust, Western Alps

Three samples of meta-acidic rocks with pre-Alpine metamorphic relicts from the Sesia-Lanzo Zone eclogitic continental crust were investigated using stepwise controlled elemental maps by means of the Quantitative X-ray Maps Analyzer (Q-XRMA). Samples were chosen with the aim of analysing the reacting zones along the boundaries between the pre-Alpine and Alpine mineral phases, which developed in low chemically reactive systems. The quantitative data treatment of the X-ray images was based on a former multivariate statistical analytical stage followed by a sequential phase and sub-phase classification and permitted to isolate and to quantitatively investigate the local paragenetic equilibria. The parageneses thus observed were interpreted as related to the pre-Alpine metamorphic or magmatic stages as well as to local Alpine re-equilibrations. On the basis of electron microprobe analysis, specific compositional ranges were defined in micro-domains of the relict and new paragenetic equilibria. In this way calibrated compositional maps were obtained and used to contour different types of reacting boundaries between adjacent solid solution phases. The pre-Alpine and Alpine mineral parageneses thus obtained allowed to perform geothermobarometry on a statistically meaningful and reliable dataset. In general, metamorphic temperatures cluster at 600–700 °C and 450–550 °C, with lower temperatures referred to a retrograde metamorphic re-equilibration. In all the cases described, pre-Alpine parageneses were overprinted by an Alpine metamorphic mineral assemblage. Pressure-temperature estimates of the Alpine stage averagely range between 420 to 550 °C and 12 to 16.5 kbar. The PT constraints permitted to better define the pre-Alpine metamorphic scenario of the western Austroalpine sectors, as well as to better understand the influence of the pre-Alpine metamorphic inheritance on the forthcoming Alpine tectonic evolution.

Quantitative X-ray mapping of Au-Ag ratios in native electrum from the Fire Creek epithermal vein deposit, Lander County, Nevada (USA)

Quantitative X-ray mapping of Au-Ag ratios in native electrum from the Fire Creek epithermal vein deposit, Lander County, Nevada (USA)

FEGSEM X-Ray Mapping System with Multiple SDDs for Quantitative X-Ray Mapping and Imaging

FEGSEM X-Ray Mapping System with Multiple SDDs for Quantitative X-Ray Mapping and Imaging

ColorSEM: Livetime Quantitative X-ray Mapping in an Integrated EDS Workflow

ColorSEM: Livetime Quantitative X-ray Mapping in an Integrated EDS Workflow

Microstructural controls on the chemical heterogeneity of cassiterite revealed by cathodoluminescence and elemental X-ray mapping

Abstract Quantitative X-ray element maps of cassiterite crystals from four localities show that Ti, Fe, Nb, Ta, and W define oscillatory zonation patterns and that the cathodoluminescent response is due to a complex interplay between Ti activated emission paired with quenching effects from Fe, Nb, Ta, and W. Sector zonation is commonly highlighted by domains of high Fe, incorporated via a substitution mechanism independent of Nb and Ta. A second form of sector zonation is highlighted by distributions of W separate to the Fe-dominant sector zone. Both sector zones show quenched cathodoluminescence and are indistinguishable under routine SEM CL imaging. For cassiterite already high in Fe (and Nb or Ta), such as in pegmatitic or granitic samples, the internal structure of the grain may remain obscured when imaged by cathodoluminescence techniques, regardless of the presence of sector zonation. Careful petrogenetic assessments using a combination of panchromatic and hyperspectral CL, aided by quantitative elemental X-ray mapping, is a prerequisite step to elucidate cassiterite petrogenetic history and properly characterize these grains for in situ microanalysis. The absence of a clear petrogenetic framework may lead to unknowingly poor spot selection during in situ analyses for geochronology and trace element geochemistry, and/or erroneous interpretations of U-Pb and O isotopic data.

The f-Ratio Quantification Method for X-ray Microanalysis Applied to Mg-Al-Zn Alloys.

The f-ratio quantitative X-ray microanalysis method has been recently developed for binary systems based on a scanning electron microscope/energy dispersive spectroscopy (SEM/EDS) system. This method incorporates traditional EDS experiments and Monte Carlo simulations, and calibration factors are calculated with standard samples to evaluate the differences between them. In this work, the f-ratio method was extended to Mg-Al-Zn multi-element systems using a cold field emission SEM and a tungsten emission SEM. Results show that the stability of the beam current does not influence the f-ratio quantification accuracy. Thus, the f-ratio method is suitable for quantitative X-ray mapping with a long-time acquisition or even an unstable beam current. Comparing with other quantitative techniques including the routine standardless analysis and the standard-based k-ratio method, the f-ratio method is a simple and accurate quantification method.

Stranski–Krastanov growth of (Si)Ge/Si(001): transmission electron microscopy compared with segregation theory

ABSTRACTWe performed transmission electron microscopy of SiGe/Si(001) and Ge/Si(001) samples that undergo the Stranski–Krastanov transition from flat layer to island growth. With the help of quantitative X-ray maps of those layers, we have determined the total amount of deposited germanium at which islanding commences. The maximum amount of Ge buried in a flat layer amounts to 2.3 monolayers. We show by modelling that it is the strain due to the total amount of Ge atoms deposited that drives the islanding process. At 600°C [400°C], 1.62 [1.74] monolayers of Ge are expected from simulations to segregate towards the surface, the strain of which is sufficient to trigger plastic relaxation by islanding, in agreement with our electron microscope observations.This is part of a thematic issue on Nanoscale Materials Characterisation and Modeling by Advances Microscopy Methods - EUROMAT.

Water-Rock Interactions in Outer Solar System Bodies: Evidence from the Coordinated Analysis of Interplanetary Dust

NASA has an ongoing program of collecting interplanetary dust particles (IDPs) in the stratosphere using high altitude research aircraft. The collected IDPs are derived from asteroids and comets and here we report studies of a subset of hydrated IDPs rich in carbonaceous matter that are proposed to have a cometary origin. Our studies are aimed at understanding the evolution of oxygen reservoirs in the Solar System and their interaction with cometary minerals and organic matter. The small size (<20 μm) and fragility of these IDPs present a number of analytical challenges. We have pioneered techniques for performing chemical, mineralogical, isotopic, and spectroscopic measurements on the same sample in a carefully coordinated sequence. Coordinated analyses of nanogram-size samples is made possible by several delicate sample preparation techniques. To avoid organic contamination, we embed IDPs in elemental sulfur and use ultramicrotomy to partly section the particles (the first few micrometers). Multiple thin sections (50-70 nm thick) are placed on different substrates depending on the analysis technique. We use a JEOL 2500SE scanning, transmission electron microscope (STEM) to determine the mineralogy, microstructure, and elemental compositions of constituent minerals in the thin sections through a combination of high resolution imaging, electron diffraction, quantitative energy-dispersive x-ray mapping, and electron energy-loss spectroscopy. Following the STEM analyses, we use a NanoSIMS 50L for high spatial resolution isotopic measurements of H, C, N, and O to search for presolar grains and to understand the origin of the indigenous organic matter. The isotopic analyses are performed on the same sections analyzed in the STEM in order to correlate isotopic properties with the elemental and mineralogical data. We reserve other thin sections for non-destructive analyses utilizing synchrotron-based techniques including Fourier-transform infrared (FTIR) micro-spectroscopy and X-ray absorption near-edge structure (XANES) analyses, especially for functional group analysis of organic matter in the particles. The remainder of the IDP is extracted from the sulfur bead that was used for microtomy and is pressed into Au foil for quantitative analysis (including light elements) using a JEOL 8530F field emission electron probe microanalyzer (EPMA). After the EPMA measurements, high precision oxygen isotopic analyses are obtained using Cameca IMS1270/1290 instruments at UCLA. The hydrated IDPs in this study are dominated by saponitic clays, with minor magnetite, carbonate and abundant organic matter. The remarkable oxygen isotopic compositions, high carbon contents, and the abundance of isotopically anomalous organic matter, together suggest that the high carbon, hydrated IDPs are derived from primitive sources not yet represented in meteorite collections such as outer main belt P- and D-type asteroids or comets.

Shock-Induced Olivine-Ringwoodite Transformation in the Shock Vein of Chondrite GRV053584

Shock metamorphism of minerals in meteorites could help to understand the shock history of its parent body and also provide a window into the interior of the Earth. Although shock features in olivine have been well known within and adjacent to shock melt veins and shock melt pockets in meteorites, there are processes that are not yet completely understood. Ringwoodite is formed by crystallization from olivine melts or solid-state phase transformation of olivine. Typically, olivine clasts with a ringwoodite rim around an olivine core have been documented from only a handful of meteorites. Here we report results from GRV053684, a highly shocked L6 chondrite that was collected by Chinese Antarctic Research Expedition in 2006 to Antarctica. The investigations of the shock pressure history and the transformation mechanism of olivine to ringwoodite use optical microscope, electron probe microanalyzer (backscattered electron images, major element quantitative analyses, and quantitative wavelength-dispersive spectrometry elemental X-ray maps), and Raman spectrograph. Ringwoodite in the shock melt vein generally displays as Fe-rich (Fa37-43) polycrystalline rims around Fe-poor (Fa11-20) olivine core and as small individual clasts embedded in shock melt vein matrix. The difference in FeO between ringwoodite rim and olivine core implies that Fe was preferentially partitioned to ringwoodite. The occurrence of maskelynite (An17) indicates a shock pressure ~30 GPa. The FeO and MgO diffusion indicates the transformation process of olivine to ringwoodite is a diffusion-controlled incoherent nucleation and growth. The spatial association between ringwoodite and the shock melt vein matrix suggests that high temperature plays a key role in prompting phase transformation.

Current State of Combined EDS-WDS Quantitative X-Ray Mapping

Current State of Combined EDS-WDS Quantitative X-Ray Mapping

Dedicated X-Ray mapping system with single and multiple SDD detectors for quantitative X-Ray mapping and data processing

Journal Article Dedicated X-Ray mapping system with single and multiple SDD detectors for quantitative X-Ray mapping and data processing Get access Richard Wuhrer, Richard Wuhrer University of Western Sydney, Advanced Materials Characterisation Facility (AMCF), Australia Search for other works by this author on: Oxford Academic Google Scholar Ken Moran Ken Moran Moran Scientific Pty Ltd, 4850 Oallen Ford Road, Bungonia, NSW, 2580, Australia Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 21, Issue S3, 1 August 2015, Pages 2191–2192, https://doi.org/10.1017/S1431927615011733 Published: 23 September 2015

Mineral Analyses &amp; Implications on the Dispersion of Bismuth in the Supergene Environment of Eastern Australia

In the Australian context, bismuth minerals are important constituents, associated with Mo, W and Sn, of highly acidic and very rich, low tonnage, deposits of the eastern ranges of Australia. Bi has been used extensively as a pathfinder element in geochemical exploration for a variety of such deposits and others and therefore it is important to understand its behaviour[1-3]. The behaviour of Bi has been described in the terms of its solution speciation as a function of pH which is well-established [4-7]and provides a first order, but simplistic, assessment of its mobility in pore solution in the regolith. Recent reviews have highlighted a lack of understanding in regards to bismuth in oxidising environments. Bismuth is estimated to have an average crustal abundance of 48 ppb [8], but is highly fractionated across different rock types and sediments with reported concentrations from 30 ppb to greater than 20 ppm an average Bi concentration in soils of 0.2 ppm but this is difficult to reconcile with the data mentioned above. A review of bismuth values [9] concluded similar concerns and further highlighted that a background ground water concentration could not be honestly concluded especially in uncontaminated environments. This is due to no independent focused study on Bi concentrations in the environment and that other factors such as sampling, testing methods and protocols were not consistent. To draw any conclusion on bismuth values, a proper understanding of the dispersion of Bi in oxidising environments must be made. This requires understanding of its low temperature aqueous chemistry and knowledge of the secondary Bi minerals that serve to buffer the element between the solid and solution states. This study used numerous natural and synthetic bismuth mineral samples and whole rock specimens. Full spectrum quantitative X-ray Mapping (XRM) was performed on a JEOL JXA 840 SEM with a Moran Scientific energy dispersive spectroscopy (EDS) Microanalysis system operated at 20kV. A JEOL 8600 EM Probe with a combined EDS and three JEOL wavelength dispersive spectrometers (WDS’s) were also used to perform trace and quantitative analysis. The analysis was undertaken at 15 kV and 20 nA. Drill core samples from the Mineral Hill mine site in regional NSW have been studied to determine the primary bismuth phases at this site which have been associated with a localised Au resource and then related to the known secondary expressions (Figure 1). Experiments have been carried out on a series of synthetic secondary bismuth minerals (Figure 2) to determine the chemical behaviour of these minerals by High Temperature X-ray Diffraction (HTXRD) and Thermogravimetric Analysis coupled with a Differential Scanning Calorimeter (TGA-DSC). These experiments have provided data which can be combined with low temperature solubility studies to give an in-depth understanding into the geochemical roles of secondary bismuth minerals in the supergene environment. For the first time a series of thermodynamic data sets for major and important bismuth mineral phases have been derived. As such a series of useful geochemical models have been

Quantitative X-ray mapping, scatter diagrams and the generation of correction maps to obtain more information about your material

Quantitative X-ray mapping with silicon drift detectors and multi-EDS detector systems have become an invaluable analysis technique and one of the most useful methods of X-ray microanalysis today. The time to perform an X-ray map has reduced considerably with the ability to map minor and trace elements very accurately due to the larger detector area and higher count rate detectors. Live X-ray imaging can now be performed with a significant amount of data collected in a matter of minutes.A great deal of information can be obtained from X-ray maps. This includes; elemental relationship or scatter diagram creation, elemental ratio mapping, chemical phase mapping (CPM) and quantitative X-ray maps. In obtaining quantitative x-ray maps, we are able to easily generate atomic number (Z), absorption (A), fluorescence (F), theoretical back scatter coefficient (η), and quantitative total maps from each pixel in the image. This allows us to generate an image corresponding to each factor (for each element present). These images allow the user to predict and verify where they are likely to have problems in our images, and are especially helpful to look at possible interface artefacts.The post-processing techniques to improve the quantitation of X-ray map data and the development of post processing techniques for improved characterisation are covered in this paper.

Effect of the Probe Size and Interaction Volume on Quantitative X-ray Maps across Interfaces of a Cu-Al Roll Bonded Laminate

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Backscattered electron images, X-ray maps and Monte Carlo simulations applied to the study of plagioclase composition in volcanic rocks

Zoning patterns in plagioclases are related to abrupt changes in the anorthite content along the crystal growing direction. Accurate characterization of these patterns by electron microprobe is useful to identify magma chamber processes such as recharge, mingling and whole-chamber overturn events.In this work, a new procedure to obtain high resolution quantitative maps of anorthite concentration in single plagioclase crystals is developed. The methodology consists of performing a calibration of backscattered electron images using quantitative X-ray maps. The ultimate resolution of characteristic X-rays and backscattered electron signals is studied by Monte Carlo simulation. The method is applied to characterize the chemical composition of a volcanic plagioclase from the Cerro Vilama, Argentina. The results obtained are more precise than the values given by the methods commonly used in the study of plagioclase composition, i.e. the classical profiling by electron microprobe point analysis or the modern backscattered electron image calibration by means of quantitative energy or wavelength dispersive X-ray analysis at a few selected points.

Variability in Chromium Segregation at Lath Boundaries in Proton-Irradiated 9 wt.% Cr Model Steel Determined by Quantitative X-Ray Mapping

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Artifacts in Qualititative and Quantitative X-Ray Mapping

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Quantitative X-ray Mapping: The Only Elemental Maps that You Should Report

Extract Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Florida, USA, August 5 – August 9, 2007

X-Ray Mapping and Interpretation of Scatter Diagrams

Electron beam induced quantitative X-ray mapping has become a very useful characterisation tool for determining the elemental distribution in materials, whether using energy dispersive spectroscopy or wavelength dispersive spectroscopy. The X-ray intensity distributions of the elements from an X-ray map allow us to generate two dimensional and ternary scatter diagrams thus converting spatial information into concentration dimensions, which is an important tool for displaying the spatial relationships of elements or correlated elements (phases) in materials. To best understand how to use this tool, we need to understand the production and features of the scatter diagram. The type of clustering observed in the scatter diagram, whether oval, linear or spherical, can give the major and trace element distributions within phases as well as qualitative and quantitative phase information. This paper demonstrates the generation of scatter diagrams, properties of scatter diagrams, interpretation of scatter diagrams and the advantages of scatter diagrams through the use of examples.

Yttrium Geothermometry Applied to Garnets from Different Metamorphic Grades Analysed by EPMA and µ-PIXE Techniques

We present a multi-analytical and multi-instrumental approach to a petrologic study of garnets from metapelites characterized by different metamorphic grades. The comparison between major, minor and trace element (Y) distribution in garnets crystallized at different temperatures was performed by electron microprobe (EDS and WDS) and the Proton Induced X-ray Emission microprobe (µ-PIXE). Two garnet samples were selected from metapelite rocks at different metamorphic grades from the tectonic unit of Stilo, Calabrian–Peloritanian Arc, Southern Italy. Quantitative spot analysis profiles and compositional X-ray maps of major elements and yttrium are reported. The major element zoning of garnets is mostly characterized by a smoothed and gradual concentric variation of all elements from core to rim. The Y concentration reveals a marked zoning with its distribution decreasing from about 7000 ppm to about 100 ppm from core to rim, respectively. The precise determination of the Y content by µ-PIXE technique allowed us to better define the rock thermal history, by applying the Y geothermometer. In particular, a common starting temperature of about 450 °C was calculated for the beginning of the garnet growth from all over the unit, but different temperatures in the range from 520 °C to 670 °C were estimated for the peak event in garnets from different areas, in agreement with the P–T values given by the main rock mineral assemblages, reflecting a different metamorphic grade.