Issues in Quantitative Phase Analysis Arnt Kern & Ian Madsen This document was presented at PPXRD - Pharmaceutical Powder X-ray Diffraction Symposium Sponsored by The International Centre for Diffraction Data This presentation is provided by the International Centre for Diffraction Data in cooperation with the authors and presenters of the PPXRD symposia for the express purpose of educating the scientific community. All copyrights for the presentation are retained by the original authors. The ICDD has received permission from the authors to post this material on our website and make the material available for viewing. Usage is restricted for the purposes of education and scientific research. PPXRD Website – www.icdd.com/ppxrd ICDD Website - www.icdd.com Issues in Quantitative Phase Analysis Limitations in accuracy and precision are mostly experimental • Mathematical basis and methodology of quantitative phase analysis is well established and work OK • Errors arise during application of methods ("PICNIC") Sample related errors • The material is not an "ideal powder" • Preferred orientation • Particle statistics • ... • Absorption • ... Issues in Quantitative Phase Analysis Operator errors • Incomplete / wrong phase identification The Reynolds Cup – what is needed to win? Mark D Raven and Peter G Self 29 July 2014 CSIRO LAND AND WATER / MINERALS RESOURCES FLAGSHIPS Non clay minerals (2002-2012) • Quartz (18) • Gypsum (2) • Apatite (1) • K-feldspar (13) • Anhydrite (2) • Tourmaline (2) • Plagioclase (14) • Alunite (1) • Zircon (2) • Calcite (12) • Hematite (6) • Spinel (1) • Dolomite (10) • Goethite (5) • Opal-CT (1) • Magnesite (4) • Magnetite (4) • Amphibole (3) • Aragonite (3) • Anatase (9) • Zeolite (1) • Huntite (1) • Rutile (3) • Epidote (1) • Halite (6) • Ilmenite (3) • Birnessite (1) • Pyrite (7) • Gibbsite (3) • Arcanite (1) • Siderite (8) • Bohmite (1) • Amorphous (6) • Barite (5) • Fluorite (2) 63rd Denver X-ray Conference 28 July – 1 August 2014, Big Sky Resort, Montana, USA | Quantitative 5 | Phase Analysis Workshop Clay minerals (2002-2012) • 2:1 Dioctahedral Clays (18) • Kaolin (15) • Smectite (montmorillonite, • Kaolinite (well and poorly ordered) nontronite) • Halloysite • Mixed layered (illite-smectite, • Dickite glauconite-smectite) • Mica/Illite (muscovite 2M , illite 1 • Chlorite (11) 1Md, 1M) • Clinochlore, Ripidolite • 2:1 Trioctahedral Clays (6) • Serpentine (2) • Smectite (saponite) • Lizardite • Vermiculite • Talc (3) • Mixed layered (corrensite) • Sepiolite (1) • Mica (biotite) • Palygorskite (1) 63rd Denver X-ray Conference 28 July – 1 August 2014, Big Sky Resort, Montana, USA | Quantitative 6 | Phase Analysis Workshop Misidentified phases (2002-2012) • Actinolite • Chrysotile • Ilmenite • Phlogopite (2M1 ) • Vermiculite • Aegerine • Clinochlore • iIterstratified (tri) • Phlogopite (mica-trioctahedral) • Vermiculite Trioctahedral • Aerinite • Clinoenstate • Iron • phosphate hydrate • Vermiculite/illite • Akaganeite • Clinoptilolite • Iron Silicon Iron • Plagioclase • Vermiculite-Smectite Trioctahedral • Albite/anorthite • ClinoPyroxene • Jarosite • Portlandite • Vesuvianite • Allophane • Clinozoisite • KAlSiO4 • Potarite • Wagnerite • Alluaudite Al -Mg• Cordierite • Kaolinite • Prehnite • Wavellite • Almandine • Corrensite • kaolinite/smectite • Pseudobrookite • Whitlockite • Al-Mg • Corundum • Kaolinite-Chlorite • Pumpellyite • Whitmoreite • AlO • Cotunnite • K-feldspar • Pyrite • Wollastonite • Alumina gamma • Cristobalite • Kieserite • Pyrolusite • Wroewolfeite • Aluminite AlO • Cryptohalite • K-rich Chlorite • pyrophyllite 1T • Wuestite • Alunite • Crysotile • Kutnohorite • pyrophyllite 2M • Zeolite • Alunogen • Diaspore • Laueite • Pyroxene • Zeophyllite • Amorphous • Dickite • Laumonite • Pyroxene (Augite) • Zinnwaldite • Amorphous (Allophane) • Dickite/Nacrite • Lepidocrocite • Pyroxene (Ferroan Diopside) • Zircon • Amorphous KAlSi3O8 • Diopside • Leucite • Pyrrhotite • Zirconium sulphate hydroxide • Amorphous Si • Dolomite • Lime • Rectorite hydrate • Amorphous SiO2 • Dolomite/Ankerite • Lithosite • Reyerite • Zoisite • Amorphous Volcanic Glass • Elpidite • Lizardite • Rhodochrosite • Amphibole • Enstatite • Magnesioferrite • Rhodonite • Analcime • Epidote • Magnesite • Rodolicoite • Anatase • Euclase • Magnetite • Rutile • Andesine • Faujasite • Malachite • Sanidine • Anhydrite • Fe oxide • Manganite • Saponite • Ankerite • Fedorite • Melantenite • Sauconite • Anorthite • Feldspar (Kspar) • Mg7Zn3 • Schorl • Antigorite • Ferrihydrite • Mg-calcite Mg7Zn3• Sepiolite • Antlerite • Ferrite magnesian • MgSO4 • Serpentine • Apatite As2O3• Fluorapatite • Mica • Siderite • Aragonite • Forsterite • Mica Trioctahedral • Siderite (Mn-rich) • Arcanite • Galeite • Mica-Vermiculite Trioctahedral • Siderite(not Mg) • Arsenolite As2O3 • Garnet • Microcline • Silicon • Augite • Gehlenite • Missing • Silicon dioxide Silicon • Barite • Gibbsite • Monazite • Sillimanite • Bazalt • Gismondine • Monohydrocalcite • Smectite trioctahedral • Berthierine • Glass/Obsidian • Montmorillonite (Tri) • Smithsonite • Biotite • Glauberite • Moschellandsbergite • Sodalite • Birnessite • Glauconite • Mullite • Spencerite • Bromcarnallite • Goethite • Nacrite • Sphalerite iron • Brookite • Gypsum • Na-Feldspar • Spinel • Brucite • Halite • Natrolite • Staurolite • Brushite C6H5O3PZn • Halite potassian • Nepheline Nitride• Strontianite • Bytownite • Halloysite • Nitride Silicon • Sylvite 260! • C6H5O3PZn • Hectonite • Nordstrandite • Syngenite • Calcite • Hedenbergite • Norrishite Silicon• Szomolnokite • CaMg2Al16O27 • Hematite • Oligoclase • Talc • Carbonate-fluorapatite • Hercynite • Olivine • Thenardite • Carnallite • Heulandite • Opal • Thermonatrite • CaSiO3 • Hexahydrite • Opal CT • Titanite • Celestine • Hornblende • Orthoclase • Titanomagnetite • Chabazite • Hotsonite • OrthoPyroxene • Tobermorite • Chalcosite • Hyalophane • Osumilite • Tourmaline • Chlorargyrite • hydrated Ca-Mg carbonate • Others not precisely identified • Trimerite • Chlorite Dioctahedral • Hydrocalumite • oxide 1 • Trydymite • Chlorite Trioctahedral • Hydrotalcite • oxide 2 • Tungstite • Chlorite-Montmorillonite(Tri) • Hydroxyapophyllite • Palygorskite • Unidentified • Chlorite-Smectite TrioctahedralChromite • Hydroxylapatite • Periclase • Unnamed hydrate • Chlorite-vermiculite • Hypersthene • Perovskite • Vaterite • Chromite • Illite Tri • Phillipsite • Vauxite 63rd Denver X-ray Conference 28 July – 1 August 2014, Big Sky Resort, Montana, USA | Quantitative 7 | Phase Analysis Workshop Issues in Quantitative Phase Analysis Operator errors • Incomplete / wrong phase identification • Incorrect crystal structures: space group, atom coordinates, occupancy factors, temperature factors • Use of poor profile / background models • Failure to refine parameters: Unit cell, profile parameters, ... • Refinement of parameters which are not supported by the data: Background, atom coordinates, occupancy factors, temperature factors, microstructure, ... Issues in Quantitative Phase Analysis Operator errors, ctd. • Inappropriate use of correction models – just because you CAN doesn’t mean you SHOULD! • Preferred orientation correction • Absorption correction • Non-constant diffraction volume • ... • Acceptance of physically unrealistic parameters (esp. thermal parameters) • Acceptance of incomplete refinements • High values of R-factors • Refined parameters not checked • Visual fit of model not checked IUCr CPD Round Robin on 0 Quantitative Phase Analysis 100 10 c • Experimental design for Sample 1 90 20 o Eight mixtures of 3 phases 80 – Corundum – -Al2O3 30 70 Zincite (wt%) – Fluorite – CaF2 40 – Zincite – ZnO 60 o Each phase present at a 50 f 50 range of concentrations 60 o ~ 1.5, 5, 15, 30, 55, 95 wt% 40 Corundum (wt%) g 70 • ‘Simple’ system 30 o Well defined phases d 80 h o Minimal peak overlap e 20 90 o Little absorption contrast 10 b 100 a0 0 10 20 30 40 50 60 70 80 90 100 Fluorite (wt%) 10 | IanIan Madsen Madsen | | CSIRO TOPAS Mineral Training Resources Course– Level 1– Flagship 2013Level 1| || Quantitative2013 | Phase Analysis | DXC2014, Big Sky, Montana IUCr CPD Round Robin on QPA 0 1a 100 CPD Supplied Data 1b 1c 1d 10 • Participant’s results 1e 90 1f o CPD-supplied data 1g 20 1h 80 – Everyone analysed the same data sets 30 o 92% of returns used Rietveld method 70 Zincite (wt%) o Note considerable spread in results 40 60 50 50 60 Corundum (wt%) 40 70 30 80 20 90 10 100 0 0 10 20 30 40 50 60 70 80 90 100 Fluorite (wt%) 11 | IanIan Madsen Madsen | | CSIRO TOPAS Mineral Training Resources Course– Level 1– Flagship 2013Level 1| || Quantitative2013 | Phase Analysis | DXC2014, Big Sky, Montana IUCr CPD Round Robin on QPA 0 1a 100 Participant Collected Data 1b 1c 10 1d 90 • Participant’s results 1e 1f o Participant collected data 1g 20 1h 80 o 75% of returns used a Rietveld method 30 70 o Spread of results is greater than Zincite (wt%) for the CPD-supplied data 40 60 • What are the sources of error ? 50 o Methods ? 50 o Sample preparation ? 60 Corundum (wt%) 40 o Data collection ? 70 o Data analysis ? 30 80 20 90 10 100 0 0 10 20 30 40 50 60 70 80 90 100 Fluorite (wt%) 12 | IanIan Madsen Madsen | | CSIRO TOPAS Mineral Training Resources Course– Level 1– Flagship 2013Level 1| || Quantitative2013 | Phase Analysis | DXC2014, Big Sky, Montana IUCr CPD Round Robin on QPA 0 Test of Various Methods 1a 100 1b 1c 10 1d 90 • Samples analysed in CSIRO labs 1e 1f 20 o 3x replicates of 8 mixtures 1g 80 1h A range of methods used • 30 70 o 2x Rietveld packages Zincite (wt%)