This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. We would also like to acknowledge Drs. L. Dobrzhinetskaya and E. O'Bannon for contributing the moissanite sample, C. Stewart for her olive snail shell data, H. Shen for preparing the olive snail shell, and G. Zhou and Prof. K. Chen for EDS measurements on the olive snail shell.

1. Set Up Beamline and Collect Data
NOTE: Calibration standards and samples are collected in the same manner, with the main difference lying in the processing method.
<ol>
	<li>Mount the sample and close the experimental hutch.
	<ol>
		<li>Attach a sample to the top half of a kinematic base (see Table of Materials) such that the ROI is vertically displaced relative to the base by at least 15 mm. 
		NOTE: A standard block exists at the beamline for use w...

<ol>
	<li>Li, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+synchrotron+study+of+defect+and+strain+inhomogeneity+in+laser-assisted+three-dimensionally-printed+Ni-based+superalloy.">A synchrotron study of defect and strain inhomogeneity in laser-assisted three-dimensionally-printed Ni-based superalloy.</a> Applied Physics Letters. 107 (18), 181902 (2015).</li><li>Zhou, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+microstructure+imaging+by+Laue+microdiffraction:+A+sample+application+in+laser+3D+printed+Ni-based+superalloys.">Real-time microstructure imaging by Laue microdiffraction: A sample application in laser 3D printed Ni-based superalloys.</a> Scientific Reports. 6, 28144 (2016).</li><li>Tippabhotla, S. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synchrotron+X-ray+Micro-diffraction+-+Probing+Stress+State+in+Encapsulated+Thin+Silicon+Solar+Cells.">Synchrotron X-ray Micro-diffraction - Probing Stress State in Encapsulated Thin Silicon Solar Cells.</a> Procedia Engineering. 139, 123-133 (2016).</li><li>Xu, C. Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elemental+Topological+Dirac+Semimetal:+&#945;-Sn+on+InSb(111)+.">Elemental Topological Dirac Semimetal: &#945;-Sn on InSb(111) .</a> Phys Rev Lett. 118 (14), 146402 (2017).</li><li>Chen, X., Tamura, N., MacDowell, A., James, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-situ+characterization+of+highly+reversible+phase+transformation+by+synchrotron+X-ray+Laue+microdiffraction.">In-situ characterization of highly reversible phase transformation by synchrotron X-ray Laue microdiffraction.</a> Appl Phys Lett. 108 (21), 211902 (2016).</li><li>Zhou, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversal+in+the+Size+Dependence+of+Grain+Rotation.">Reversal in the Size Dependence of Grain Rotation.</a> Phys Rev Lett. 118 (9), 096101 (2017).</li><li>Stan, C. V., Beavers, C. M., Kunz, M., Tamura, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=X-Ray+Diffraction+under+Extreme+Conditions+at+the+Advanced+Light+Source.">X-Ray Diffraction under Extreme Conditions at the Advanced Light Source.</a> Quantum Beam Science. 2 (1), 4 (2018).</li><li>Chen, K., Kunz, M., Tamura, N., Wenk, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Residual+stress+preserved+in+quartz+from+the+San+Andreas+Fault+Observatory+at+Depth.">Residual stress preserved in quartz from the San Andreas Fault Observatory at Depth.</a> Geology. 43 (3), 219-222 (2015).</li><li>Chen, K., Kunz, M., Tamura, N., Wenk, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+for+high+stress+in+quartz+from+the+impact+site+of+Vredefort,+South+Africa.">Evidence for high stress in quartz from the impact site of Vredefort, South Africa.</a> Eur J Mineral. 23 (2), 169-178 (2011).</li><li>Jackson, M. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Material+and+Elastic+Properties+of+Al-Tobermorite+in+Ancient+Roman+Seawater+Concrete.">Material and Elastic Properties of Al-Tobermorite in Ancient Roman Seawater Concrete.</a> J Am Ceram Soc. 96 (8), 2598-2606 (2013).</li><li>Jackson, M. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phillipsite+and+Al-tobermorite+mineral+cements+produced+through+low-temperature+water-rock+reactions+in+Roman+marine+concrete.">Phillipsite and Al-tobermorite mineral cements produced through low-temperature water-rock reactions in Roman marine concrete.</a> Am Mineral. 102 (7), 1435-1450 (2017).</li><li>Gilbert, P. U. P. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nacre+tablet+thickness+records+formation+temperature+in+modern+and+fossil+shells.">Nacre tablet thickness records formation temperature in modern and fossil shells.</a> Earth Planet Sc Lett. 460, 281-292 (2017).</li><li>Mass, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amorphous+calcium+carbonate+particles+form+coral+skeletons.">Amorphous calcium carbonate particles form coral skeletons.</a> P Natl Acad Sci. 114 (37), E7670-E7678 (2017).</li><li>Marcus, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Parrotfish+Teeth:+Stiff+Biominerals+Whose+Microstructure+Makes+Them+Tough+and+Abrasion-Resistant+To+Bite+Stony+Corals.">Parrotfish Teeth: Stiff Biominerals Whose Microstructure Makes Them Tough and Abrasion-Resistant To Bite Stony Corals.</a> ACS Nano. 11 (12), 11856-11865 (2017).</li><li>Kunz, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+dedicated+superbend+x-ray+microdiffraction+beamline+for+materials,+geo-,+and+environmental+sciences+at+the+advanced+light+source.">A dedicated superbend x-ray microdiffraction beamline for materials, geo-, and environmental sciences at the advanced light source.</a> Rev Sci Instrum. 80 (3), 035108 (2009).</li><li>Beckhoff, B., Kanngie&#223;er, B., Langhoff, N., Wedell, R., Wolff, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Practical X-Ray Fluorescence Analysis. , (2007).</li><li>Tamura, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=XMAS:+A+Versatile+Tool+for+Analyzing+Synchrotron+X-ray+Microdiffraction+Data.">XMAS: A Versatile Tool for Analyzing Synchrotron X-ray Microdiffraction Data.</a> Strain and Dislocation Gradients from Diffraction. , 125-155 (2014).</li><li>Dobrzhinetskaya, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Moissanite+(SiC)+with+metal-silicide+and+silicon+inclusions+from+tuff+of+Israel:+Raman+spectroscopy+and+electron+microscope+studies.">Moissanite (SiC) with metal-silicide and silicon inclusions from tuff of Israel: Raman spectroscopy and electron microscope studies.</a> Lithos. , (2017).</li><li>Thibault, N. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphological+and+structural+crystallography+and+optical+properties+of+silicon+carbide+(SiC):+Part+II:+Structural+crystallography+and+optical+properties.">Morphological and structural crystallography and optical properties of silicon carbide (SiC): Part II: Structural crystallography and optical properties.</a> American Mineralogist. 29 (9-10), 327-362 (1944).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Electron Backscatter Diffraction in Materials Science. , (2009).</li></ol>

We present a method for combined x-ray diffraction and XRF analysis of crystalline samples at ALS beamline 12.3.2. While neither Laue diffraction, powder diffraction, nor XRF themselves are novel methods, beamline 12.3.2 combines them as well as a micron-scale x-ray beam size, a scanning stage system that is correlated to detector exposure triggers, and a comprehensive analysis software to allow for experiments that would not be possible on laboratory instruments. Photon flux at the beamline is several orders of magnitud...

Crystalline samples frequently display heterogeneity on the micron scale. In geoscience, the identification of minerals, their crystal structure, and their phase relations in 2D systems is important for understanding both the physics and chemistry of a particular system, and requires a spatially-resolved, quantitative technique. For example, relationships between minerals can be examined based on the phase distribution within a localized 2D region. This can have implications for the history and chemical interaction that may have occurred within a rocky body. Alternatively, the material structure of a single mineral can be examined; this may determine the types of deformation that the mineral may have been or is currently being subjected to (such as in the case of an in situ deformation experiment with a device like the diamond anvil cell). In geoscience, these analyses are often performed using a combination of scanning electron microscopy (SEM) with energy or wavelength dispersive x-ray spectroscopy (E/WDS) and electron backscatter diffraction (EBSD). However, sample preparation can be difficult, involving extensive polishing and mounting for vacuum measurements. Also, EBSD is a surface technique that requires relatively unstrained crystals, which is not always the case for geological materials which may have experienced uplift, erosion, or compression.
Spatially-resolved characterization using 2D x-ray microdiffraction and XRF mapping, as is available at beamline 12.3.2 of the ALS, is a fast and straightforward way of making large area maps of single or multiphase systems where the crystal size is on the scale of a few nanometers (in the case of polycrystalline samples) to hundreds of microns. This method has many advantages when compared to other commonly used techniques. Unlike other 2D crystal mapping techniques, such as EBSD, microdiffraction samples can be measured at ambient conditions, and thus do not require special preparation as there is no vacuum chamber. Microdiffraction is suitable for crystals that are pristine as well as those which have experienced severe strain or plastic deformation. Samples such as thin sections are commonly examined, as are materials embedded in epoxy, or even unaltered rocks or grains. Data collection is fast, usually less than 0.5 s/pixel for Laue diffraction, less than 1 min/pixel for powder diffraction, and less than 0.1 s/pixel for XRF. Data are stored locally, temporarily on a local storage, and more permanently at the National Energy Research Scientific Computing (NERSC) center, from which it is easy to download. Data processing for diffraction can be performed on a local cluster or on a NERSC cluster in under 20 min. This allows for fast throughput in data collection and analysis, and for large area measurements over a short period of time when compared to laboratory instruments.
This method has a wide variety of applications and has been used extensively, particularly in materials science and engineering, to analyze everything from 3D-printed metals1,2, to solar panel deformation3, to strain in topological materials4, to memory alloy phase transitions5, to the high-pressure behavior of nanocrystalline materials6,7. Recent geoscience projects include the analysis of strain in various quartz samples8,9 of volcanic cementitious processes10,11, and also of biominerals such as calcite and aragonite in shells and corals12,13 or apatite in teeth14, and additional studies on meteorite phase distribution, mineral structure identification of new minerals, and plastic deformation response in high-pressure silica have also been collected. The techniques used at beamline 12.3.2 are applicable to a broad range of samples, relevant to anyone in the mineralogical or petrological communities. Here we outline the data acquisition and analysis protocol for beamline 12.3.2, and present several applications in order to demonstrate the usefulness of the combined XRF and Laue/powder microdiffraction technique in the geoscience field.
Before going into experimental detail, it is germane to discuss the setup of the end-station (see Figure 1 and Figure 4 in Kunz et al.15). The x-ray beam exits the storage ring and is directed using a toroidal mirror (M201), the purpose of which is to refocus the source at the entrance of the experimental hutch. It passes through a set of roll slits which function as a secondary source point. It is then monochromatized (or not) depending on the experiment type, before passing through a second set of slits and being focused to micron sizes by a set of Kirkpatrick-Baez (KB) mirrors. The beam then passes through an ion chamber, whose signal is used to determine beam intensity. Attached to the ion chamber is a pinhole, which blocks scattered signal from impinging onto the detector. The focused beam then encounters the sample. The sample is placed on top of a stage, which consists of 8 motors: one set of rough (lower) x, y, z motors, one set of fine (upper) x, y, z motors, and two rotation motors (&#934; and &#967;). It can be visualized with three optical cameras: one with low zoom, placed at the top of the ion chamber, one with high zoom, placed in a plane at an approximately 45&#176; angle with respect to the x-ray beam, and a second high-zoom camera placed at a 90&#176; angle with respect to the x-ray beam. This last one works best for samples that are oriented vertically (such as for a transmission mode experiment), and imaging is performed using a wedge-shaped mirror attached to the pinhole. The x-ray diffraction detector is located on a large rotating stage, and both the angle and the vertical displacement of the detector can be controlled.&#160;A silicon drift detector to collect XRF is also present. Samples can be prepared in any manner, as long as the exposed region of interest (ROI) is flat (on the micron scale) and uncovered or covered in no more than ~50-100 &#181;m of x-ray transparent material such as polyimide tape.
The procedure outlined below describes an experiment that takes place in reflective geometry, and assumes the z direction is normal to the sample and x and y are the horizontal and vertical scanning directions, respectively. Because of the flexibility of the stage and detector system, however, some experiments are performed in transmission geometry, where the x and z directions are the horizontal and vertical scanning directions, while y is parallel to the direct beam (see Jackson et al.10,11).

<table border="0" cellpadding="0" cellspacing="0" width="784">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:285px;">ThorLabs KB3x3 kinematic base, top half</td>
			<td style="width:213px;">ThorLabs</td>
			<td style="width:119px;">KBT3X3</td>
			<td style="width:167px;">Several of these bases are available for borrowing. The base must be the imperial and not the metric type, otherwise it will not properly fit on the stage.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:285px;">Scotch double sided tape</td>
			<td style="width:213px;"></td>
			<td style="width:119px;"></td>
			<td>Available at any office supply store, and also at the beamline</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:285px;">Polyimide/Kapton tape</td>
			<td style="width:213px;">Dupont</td>
			<td style="width:119px;"></td>
			<td>Several widths are commercially available. Any width that is enough to cover the sample is fine.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:285px;">Samples</td>
			<td style="width:213px;"></td>
			<td style="width:119px;"></td>
			<td>Provided by user, site of interest should be polished if larger mapping is desired.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:285px;">Software: XMAS</td>
			<td style="width:213px;"></td>
			<td style="width:119px;"></td>
			<td>Downloadable here https://sites.google.com/a/lbl.gov/bl12-3-2/user-resources</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:285px;">Software: IDL 6.2</td>
			<td style="width:213px;">Harris Geospatial Solutions</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:285px;">X-ray Diffraction Detector</td>
			<td>DECTRIS Pilatus 1M&#160;</td>
			<td style="width:119px;"></td>
			<td>hybrid pixel array detector</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Huber stage</td>
			<td style="width:213px;"></td>
			<td style="width:119px;"></td>
			<td>stage for detector</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vortex silicon drift detector&#160;</td>
			<td style="width:213px;"></td>
			<td style="width:119px;"></td>
			<td>silicon drift detector</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">IgorPro v. 6.37</td>
			<td style="width:213px;"></td>
			<td style="width:119px;"></td>
			<td>Plotting software</td>
		</tr>
	</tbody>
</table>

synchrotron x-ray microdiffraction and fluorescence imaging of mineral and rock samples

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder microdiffraction two-dimensional (2D) maps at beamline 12.3.2 of the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. Measurements can be performed on any sample that is less than 10 cm x 10 cm x 5 cm, with a flat exposed surface. The experimental geometry is calibrated using standard materials (elemental standards for XRF, and crystalline samples such as Si, quartz, or Al2O3 for diffraction). Samples are aligned to the focal point of the x-ray microbeam, and raster scans are performed, where each pixel of a map corresponds to one measurement, e.g., one XRF spectrum or one diffraction pattern. The data are then processed using the in-house developed software XMAS, which outputs text files, where each row corresponds to a pixel position. Representative data from moissanite and an olive snail shell are presented to demonstrate data quality, collection, and analysis strategies.

Laue Microdiffraction
A recent measurement and analysis was performed on a natural moissanite (SiC) sample18. The sample consisted of a piece of tuff embedded in an epoxy plug, which was then cut and polished to expose the ROI. Three moissanite grains were identified using optical microscopy and Raman spectroscopy (Figure 1a). One of the grains, SiC 2 (<stron...

Watch this Scientific Journal Video about Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples at JoVE.com

Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples

We describe a beamline setup meant to carry out rapid two-dimensional x-ray fluorescence and x-ray microdiffraction mapping of single crystal or powder samples using either Laue (polychromatic radiation) or powder (monochromatic radiation) diffraction. The resulting maps give information about strain, orientation, phase distribution, and plastic deformation.

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder ...

This method can help answer key questions in mineralogy and petrology about grain and phase distribution and mineral physics and chemistry. The main advantage of x-ray microfluorescence and x-ray microdiffraction is to provide correlated elemental and crystallographic analysis at the micron scale while accommodating sample with size up to 10 centimeter and without the need of any vacuum chamber. Samples can be thin sections, they can be embedded in epoxy, or they can even be whole unadulterated rocks, making sample preparation much simpler for this technique compared to other comparable techniques, such as EBSD.Further, unlike EBSD, this technique allows us to measure natural and synthetic samples that have undergone plastic deformation, such as metamorphic rocks. To begin, attach a crystalline sample to the top half of a kinematic base so that the region of interest is vertically displaced relative to the base by at least 15 millimeters. Mount the top half of the base on the stage in the experimental hutch, and close the hutch.Open the beamline control software, and initialize the program. Initialize the translation stage and slit controls. Once the beamline control program has been completely turned on, open the x-ray diffraction scan software.Then, turn on the alignment laser, and open the stage setup menu. Translate the sample stage so that the sample ROI is within approximate visual focus of the rough alignment camera. Now, looking at the fine-focus camera, translate the upper z motor until the laser spot is aligned with the mark on the screen.Then, open the slit setup menu. Select the appropriate slit size and, if needed, the monochromator energy. Use the mirror jog control to slowly tune the toroidal mirror to maximize the ion chamber count value.Then, initialize fluorescence mapping, and set the measurement data file path. Provide energy ranges for up to eight elements of interest. Use the upper x and y motors to drive the sample stage to one corner of the area to be mapped.Mark this as the start position for the x and y axes. Then, drive the stage to the opposite corner, and mark it as the end position for the x and y axes. Fill in the step size and either the velocity or dwell time for the scan.Confirm that the map covers the sample ROI, and start the scan to map the sample with x-ray fluorescence. Once the x-ray fluorescence scan has finished, provide a folder name and naming scheme for data files in the x-ray diffraction scan window. Ensure that the upper x and y motors are selected.Fill in the x and y start and end positions, step sizes, and pattern exposure time. Launch the mapping process, and wait for the scan to finish. To begin single crystal microdiffraction analysis, load a single crystal diffraction pattern into the analysis software, and subtract the detector background.Then, open the calibration parameter menu, and load the appropriate calibration parameter file. Load a standard crystal structure. If necessary, also load a stiffness file with the third-order elastic tensor matrix for the material.Then, open the peak search tool. Set the desired peak threshold, and run the automatic peak picking process. Manually add or remove peaks as needed.Initialize the indexing process. If stress will be quantified, also load the stiffness file associated with the structure, and select the appropriate stress parameters. Initialize the strain calculation.Then, open the automatic analysis procedure window. Set the first file in the map sequence as the image file parameters, and fill in the last file number. Provide a name for the file to be created.Then, fill in the user directory, the path to the images, the file location where processed files should be saved, and the number of nodes to be used in the calculation. Generate and save the instruction file. Upload the instruction file to the cluster using a file transfer program.Then, open a terminal window, and run the parameter calculation. Provide the instruction file name when prompted. Once the parameter calculation process has finished, copy the output file to the local computer, and load the file into the analysis program.Display the map, and select the column that will correspond to the z-values of the 2D plot. Export the data to another plotting program if desired. To begin powder microdiffraction analysis, load a powder diffraction pattern into the analysis software, subtract the detector background, and load the calibration parameter file.Hover the cursor over pixels in the pattern corresponding to a peak of interest, and note the displayed two-theta and chi values. Then, open the window for integrating the pattern as a function of two-theta, and fill in the two-theta and chi ranges. Select a Gaussian or Lorentzian fit, ensure that the fit is a good visual match, and fit the peak.Next, open the chi-two-theta analysis window, and select the path to the files to be mapped. Fill in the start and end numbers from the sequence. Name the result file, and run the scan to map the previously fit peak onto each pattern.Then, integrate one peak across chi, and map it across a 2D map. Export the data to another plotting program if desired. A moissanite sample thought to contain native silicon was first evaluated by x-ray fluorescence.The intensity range excluded silicon and carbon, allowing the silicon carbide crystal to be distinguished as a low-intensity area compared to the surrounding calcium and iron-rich material. Laue x-ray diffraction patterns were then acquired. Initial indexing of a pattern within the sample body showed a better fit for the 4H silicon carbide polytype than the 6H silicon carbide polytype.Most of the crystal was easily indexed with 4H silicon carbide. Manual examination of the remaining crystal area showed that this portion was better indexed as 6H silicon carbide. A 6H silicon carbide indexing map of this section had low success in one area.Within that area, several overlapping diffraction patterns were observed, which indexed as at least three overlapping silicon grains. It is important to manually verify that an automated fit is performed correctly. Here, manual verification allowed us to determine that different parts of the sample actually have different crystal structures and that there's multiple silicon grains present.Multiple local maxima occurred at the bases of the peaks, indicating multiple subgrains resulting from significant plastic deformation. Powder microdiffraction of an olive snail shell showed that the aragonite pattern was a good match. XRF maps of calcium and iron suggested compositional variation in line with the maps of the aragonite 040 peak width, d-spacing, integrated intensity, and orientation.The apparent correlation between iron and the d-spacing and orientation was found to be a measurement artifact. Sometimes the measurements must be verified by other analytical tools. For instance, EDS measurements indicate that what we thought was compositional variation was in fact due to diffraction from texture aragonite layers.After watching this video, you should have a good understanding of how straightforward data collection and processing is for x-ray fluorescence and microdiffraction at ALS 12.3.2. Once mastered, data collection can be very fast, up to 100 pixel per minute. Data analysis can take as little as five minutes when performed on the cluster.This technique has successfully been used by researchers in order to analyze the strain of quartz and other silica polymorphs to look at the mineralogy of Roman and volcanic concretes, to look at meteorological composition, as well as for analysis of calcite and aragonite in various shells and corals. Complementary method like EDS or EBSD can be performed to answer additional question, such as quantifying elemental distribution. Don't forget that, as with all automated processes, data should be checked manually in order to verify that it was collected and processed correctly.

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8.8K visualizações.  Lawrence Berkeley National Laboratory. This method can help answer key questions in mineralogy and petrology about grain and phase distribution and mineral physics and chemistry. The main advantage of x-ray microfluorescence and x-ray microdiffraction is to provide correlated elemental and crystallographic analysis at the micron scale while accommodating sample with size up to 10 centimeter and without the need of any vacuum chamber. Samples can be thin sections, they can be embedded in epoxy, or they can even be whole unadulterat...