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Claylab Applied Geology & Mineralogy

Claylab Applied Geology & Mineralogy. X-ray diffraction A tool for material characterization and mineral quantification. Rieko Adriaens rieko.adriaens @ ees.kuleuven.be. 23/01/2013. X-ray diffraction on mineral powders. Mono- chromator. Antiscatter- slit. Divergence slit.

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Claylab Applied Geology & Mineralogy

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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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