CETAS Düsseldorf Progress in XRD analysis using the Rietveld method on selected samples. Thomas Bach

Transkript

1

2

3

4 CETAS Düsseldorf 2015 Progress in XRD analysis using the Rietveld method on selected samples Thomas Bach by Dorfner ANZAPLAN GmbH, D Hirschau, Germany Düsseldorf, Progress in XRD analysis using the Rietveld method on selected samples Content Introduction Business of Anzaplan XRD Rietveld Basics Examples Quantification of Lithium Quantification of Siphases Quantification of Austenite Summary

5 3 Dorfner - Anzaplan The Service Company Dorfner Group of Companies Foundation in 1895 Construction of a kaolin works at the largest kaolin deposit in Germany near Hirschau (Bavaria) Experience since more than 100 years in mining, handling, processing and upgrading of industrial minerals Founded in 1985 to become the most independent venture within the Dorfner Group. Analytics Quality at the highest level by official licenses, certification and accreditation in glass, ceramics and raw materials. Process Engineering Independent from any machinery manufacturer Anzaplan is committed to the best process design and innovative concepts in industrial minerals processing.

6 ANZAPLAN Analytical Services Quality at the highest level XRD Rietveld Basics Principle Bragg s Law n λ = 2d sin (2Θ) Rietveld Hugo Rietveld, Physicist Quantification of crystalline phases by fitting a theoretical line profile to the observed line profile ANZAPLAN analytical services department covers three main topics: Raw material analysis Product analysis (glass, ceramics, cement, etc.) Water analysis Dorfner Anzaplan and its laboratory are assigned by the DaKKS-accreditation chamber, a sig-natory of the International Laboratory Accreditation Cooperation (ILAC). Therefore analyses and testing by Anzaplan are internationally accepted. Services by Dorfner Anzaplan are certified and approved by DIN 17025, ISO 9001 and ISO for chemical and physical analyses, process engineering, research and development, for basic materials, industrial mineral products and systems, and environmental technology α α δ α d s =2δ α α

7 Rietveld Basics Rietveld requirements Hardware: XRD instrument => D8 (Bruker) Fast detector => Lynxeye detector; 200x faster than Scintillation counter Good counting statistics High angle resolution Quick results Rietveld Basics Rietveld requirements Software: Database ICSD, Karlsruhe ICDD, USA pdf4 database Rietveld Software => TOPAS, Bruker Fast Computer for huge data processing / Iteration steps Rietveld procedure Identification of all crystalline phases in the sample For all identified phases the structural data must be known (given by ICSD or ICDD) Instrument parameters must be setup best done by instrument manufacturer and by running monitor samples If possible: adding an internal standard Line profile fitting

8 Lithium-Pegmatite New Concept Essential properties of pegmatites are: coarse crystal size differences in color difference in morphology In this example: spodumene exhibits as green, elongated particles quartz is clear feldspars are milky or slightly reddish. Polished section of a lithium pegmatite Analytical Methods for Lithium Other Techniques X-Ray Fluorescence (XRF) not possible Flame Emission Spectroscopy Atomic Absorption Spectroscopy (AAS) Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) Wet chemistry methods Colorimetry XRD Advantages Fast Easy sample preparation Quantification possible with Rietveld XRD Drawbacks Expensive Well trained technicians needed

9 Settings D8 Instrument Messmethode Tube Current Detector D8 Standard (AZ) 40 kv / 40 ma Lynx-Eye Fixed slit 0,12 2 Theta (angle) Start 5 Stop 65 Step size 0,015 Step time Measurement time 0,3 s 21 min Li2O Li2O RWP LIMS ICP D8 D ,88% 1,9% 24, ,20% 3,5% 23, ,62% 1,5% 17, ,06% 3,1% 17, ,61% 1,8% 18, ,41% 2,4% 20, ,35% 4,6% 17, ,24% 1,2% 17, ,84% 2,9% 19, ,50% 4,9% 16, ,43% 2,4% 18, ,89% 4,7% 16, ,39% 1,3% 23, ,71% 1,8% 20, ,61% 1,8% 20, ,13% 1,9% 21, ,15% 4,3% 15, ,82% 1,8% 23, ,06% 3,1% 19, ,66% 6,0% 19,116 XRD Results D 8 7,0% 6,0% 5,0% 4,0% 3,0% 2,0% 1,0% Li2O D8 0,0% 0,00% 2,00% 4,00% 6,00% y = 1,0602x - 0,001 R² = 0,9876 Li2O D8 Linear (Li2O D8)

10 SiC SiC Si Phases Instrument D8 Standard Messmethode (AZ) Tube Current 40 kv / 40 ma Detector Lynx-Eye Fixed slit 0,12 2 Theta (angle) Start 5 Stop 65 Step size 0,015 Step time 0,3 s Measurement time 21 min

11 Austenite XRD measurements X-Ray Tube: Cr radiation No fluoresence with steel samples Good resolution Mo radiation short wavelength to increase the number of diffraction peaks Co radiation Particular suitable when complete diffraction pattern needs to be measured Cu radiation Needs energy dispersive detector because of sample fluorescence Limited penetration depth Austenite XRD measurements XRD Settings for Cu radiation Instrument D8 D8 D8 D8 D5000 Standard Standard + Extended + Method (AZ) Discriminator discriminator Tube Current 40 kv / 40 ma 40 kv / 40 ma 40 kv / 40 ma 40 kv / 40 ma Detector Scintillation Lynx-Eye Lynx-Eye Lynx-Eye Primary slit 0,12 0,12 0,12 0,12 Secondary slit 2,32 2,32 2,32 2,32 2 Theta (angle) Start Stop Step size 0,015 0,015 0,02 0,005 Step time 1 s 0,3 s 1,5 s 3 s Measurement time 50 min 21 min 100 min 600 min

12 Austenite Sample DD Austenite: Rietveld refinement

13 Austenite DH Austenite: Rietveld refinement

14 Progress in XRD analysis using the Rietveld method on selected samples Summary Rietveld refinement is successful for Quantification of elements, i.e. Li Phase quantification of Si-phases (SiC, ) Element (N) quantification from Si3N4, Si2ON2 Quantification of Austenite in steel