Specimen Preparation XRD Pikes Peak 1 & 2 T. Fawcett, International Centre for Diffraction Data, Newtown Square, PA N. Bhuvanesh, Texas A&M University, College Station, TX S. Quick, Pennsylvania State University, State College, PA M. Rodriguez, Sandia National Laboratory, Albuquerque, NM

Instructors 14 Years ICDD clinic instructor Assistant Prof. Computer Sci & Eng. Materials Laboratory at Sandia Specializes in in-situ diffraction, over 100 publications Dr. Nattamai Bhuvanesh Texas A & M University College Station, Texas X-ray Diffraction Laboratory, TAMU “Principles and Applications in Powder Diffraction” 22 Years at Dow Chemical, 10 at ICDD Over 40 publications

Agenda Break at ~10:15-10:30 Introduction Tim Particle Statistics Mark Cavity Mounts Sue Small or thin specimens Bhuv Our tricks All Break at ~10:15-10:30

Critical References “Preparation of Specimens for X-ray Fluorescence and X-Ray Diffraction Analysis”, Victor E. Buhrke, Ron Jenkins, Deane K. Smith (+ 30 friends), Wiley-VCH Publishers,1998 Selected Resources for X-ray Diffraction, Methods and Practices CD- ROM – “Sample Preparation Methods in X-ray Powder Diffraction” 2004 “Introduction to X-Ray Powder Diffractometry”, Ron Jenkins, Robert L. Snyder”, Wiley-Interscience Publisher, 1996 “X-Ray Diffraction Procedures for Polycrystalline and Amorphous Materials”, Harold P. Klug and L. R. Alexander, Wiley-Interscience, 1974 “X-Ray Diffraction Methods in Polymer Science”, L. R. Alexander, Wiley-Interscience, 1969 (Note: Hard to find), Kreiger Publishing, 1979

Specimen Preparation – Free Download, Advances in X-ray Analysis http://www.icdd.com/

Specimen Preparation Cast of thousands ! Contributions by global authors, references summarize work of many researchers Definitions Sample material supplied by requestor Specimen portion of sample presented to instrument

Goal of Specimen Preparation Prepare a specimen for the diffraction experiment which is representative of the sample to provide the information needed to answer the question posed. Ideally, no more time and effort should be required or expended than is necessary to meet the above goal.

Goal of Specimen Preparation An elaborate procedure is not necessary for phase confirmation Know and understand the question before starting the procedure (assumes that the requestor understands what is really needed)

Every time you prepare a sample you change it ! Make sure the sample prep technique is not destroying, altering or masking the original problem (tip - analyze before and after preparation steps) Grinding can destroy soft materials Binders can mask or dilute phases - Temperature and humidity can change phase chemistry Sieving may separate phases as well as separating particle size

Elements of Sample Prep Basic statistics Representative samples from bulk Sampling procedures (macro) Grinding Absorption and microabsorption problems Crystallinity and particle effects Specimen configuration and equipment geometry Depth of penetration Surface roughness Background, specimen holders Crystal perfection and extinction Concentration phases Slurries and slurry mounts, analyzing films, flowing materials Use of internal standards Atmosphere sensitive or toxic materials Special chemistries (metals, drugs, minerals, thin films, gems, explosives, polymers, nanomaterials) Temperature and Pressure Studies

Container says Plaster of Paris (CaSO4). It looks Peak Shift 0.05 degrees Sample was so high that it was not in the focusing plane. Container says Plaster of Paris (CaSO4). It looks this stuff has grabbed H2O and CO2 from the air over time Sample holder Red scan – Nice data but thin preparation resulted in diffraction from aluminum substrate Green Data – Very thin film on glass – too thin not enough intensity/particles Black data – Thick preparation – assymmetry in the peaks but otherwise OK Thin layer prep CTIMP1a.raw

Specimen Prep – Macro to Micro Courtesy of PANalytical Courtesy FBI

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Macro to Micro - Mountains to molehills Riffle Splitters Jaw Crushers Sample Thieves Pulverizer Mills (large) Slicers & Dicers Micro Mortar & Pestle Ball mill (small) Particle Sieve Particle size (microns) Particle Orientation Particle mixing

Resources at DXC ! Angstrom Inc. Chemplex Industries (pulverizers, presses) Chemplex Industries (mills, grinding media, thin films) Corporation Scientifique Claisse (weighing stations) Herzog Automation (automated preparation systems) Premier Lab Supply (presses, binders) Rocklabs Ltd (mining and ore prep) SPEX SamplePrep (cryogenic mill, films)

What is usually going to cause you trouble? Peak Width Intensity - Y-Axis Particle statistics influence intensities via orientation Specimen displacement influences position Both particle statistics and specimen displacement influence peak profiles Position - X-Axis (d-spacing)