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X-ray Diffraction for Material Characterization and Mineral Quantification

This article discusses the use of X-ray diffraction (XRD) as a tool for material characterization and mineral quantification in applied geology and mineralogy. It covers the principles of XRD, the equipment used, and the challenges and disadvantages of traditional sample preparation methods. It also presents a standardized procedure for sample preparation and introduces the Rietveld method for accurate quantification and structure analysis. Practical information and support for XRD measurements are provided.

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X-ray Diffraction for Material Characterization and Mineral Quantification

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  1. ClaylabAppliedGeology & Mineralogy X-raydiffraction A tool formaterialcharacterization and mineralquantification Rieko Adriaens rieko.adriaens@ees.kuleuven.be 23/01/2013

  2. X-ray diffraction on mineral powders Mono- chromator Antiscatter- slit Divergence slit Detector- slit Tube Sample

  3. θ 2 Diffractionpattern Detector Tube θ Sample focusing-circle measurement circle

  4. Unique fingerprintforanorganicsubstances a = b = c o 90 = = = c a b

  5. crystalline Amorphous

  6. Errors in XRD – analysis: Vendor competition Sample preparation Measurement Identification Quantification

  7. Sample preparation: Classicalapproach • Manualgrindingusingmortar & pestle • Back/top loading of holderapplyingpressure

  8. Classicalapproach: disadvantages • Presence of coarseparticles and bad loadingcauseseveralnegativeeffects: • Extreme preferredorientation • Patternshifts • Verypoorreproducibility • Complex identification & wrong quantification

  9. Classicalapproach: disadvantages • Preferredorientation & patternshifts XRD pattern: Ideal case

  10. Classicalapproach: disadvantages • Preferredorientation: Cleavageplanes & prominent crystalfaces Halite Quartz Gypsum Mica

  11. Classicalapproach: disadvantages • Preferredorientation & patternshifts • Verypoorreproducibility !!!

  12. Bulk XRD – analysis • Disadvantagesimpede accurate Q-XRD • Neccessity of standardizedpreparation procedures We need a procedure whichmakessurethat: • Particlesshouldbefinerthan <50µm • Wet grindinginstead of dry grinding • Particles are randomlyoriented in the measurementholder • Sample surfaceshouldbesmooth and perfectly flat • Reproducible & representativemeasurements

  13. Standardized procedure afterSrodon, 2001 • Powder mixed withinternalstandard (ZnO, Al2O3, TiO2 ) • Grinding media (Al2O3, Yttriastabilized Zr) • Grinding agent: methanol/ ethanol • McCronemicronizingmill (5min.) • Side loadfilling / nopressure top load

  14. Standardized procedure afterSrodon, 2001 • Good random orientation of crystallitesobtained BUT canbeimprovedby the making of sphericalgranules: use of Vertrel XF treatment, spray dryingequipment, elvacitetreatment,… Kaolinite Portland cement

  15. Standardized procedure: Validation Classic methodology Renewedmethodology

  16. Standardized procedure: Validation Muchlesspreferredorientation Classic methodology Renewedmethodology

  17. Standardized procedure afterSrodon, 2001 • Allows accurate Q-XRD analysis

  18. Otherpossibilities

  19. [The Rietveld Method] • Most powerfulmethodforcombinedquantification and structureanalysis • Relieson the refinement of basictheoreticalstructures • Minimizedifferencebetweencalculated XRD pattern and measured XRD pattern

  20. Rietveld refinement: procedure • Measure the diffractionpattern of the sample • Comparebothpatterns • Refine parameters and recalculatepattern • Draw info from the refined data (crystallitesizes / quantitativephaseinformation / …) • Introducereasonablestarting models / values to calculate a diffractionpattern

  21. Whatcanbeevaluatedwith a Rietveld refinement ? • Example: Cement Fullyamorphousblastfurnace slag ZnO as internalstandard

  22. Whatcanbeevaluatedwith a Rietveld refinement ? <10nm crystallites • CrystalliteSizes / Strain • Absolute Crystallitesizes Usefulfor: • Processoptimisation • Product characterisation • Product qualityassesment Finercrystallites are prone to reactfaster (or to reactbetter as catalysts, etc.) • Assessment of crystalliteshape (in case of anisotropicpeaksizebroadening)

  23. Whatcanbeevaluatedwith a Rietveld refinement ? • SolidSolution • Example: Fe-richDolomite (CaMg(CO3)2) – Ankerite (CaFe(CO3)2) • Change in lattice parameters as a function of the Fe-content With a Rietveld refinement; Lattice parameters and henceFe-contentscanbeaccuratelydetermined Example: Fe-richDolomite/Ankerite in Sedimentary rock: Exact average formula: Ca(Fe0,46Mg0,54)(CO3)2 Fe-Dolomite

  24. Practical information

  25. Practical information 1st floor Software computers XRD rooms Groundfloor 1st floor

  26. Practical information Reservationshttps://ees.kuleuven.be/reservations/xrd/calendar/index.html

  27. Practical information Measurementsoverview list

  28. Practical information Technical support: Dirk Steeno dirk.steeno@ees.kuleuven.be 200C – 00.89 General support: Rieko Adriaens rieko.adriaens@ees.kuleuven.be 200E – 03.217 Responsible professor: Jan Elsen jan.elsen@ees.kuleuven.be 200E – 02.207

  29. Questions / more information Contact rieko.adriaens@ees.kuleuven.be

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