Event Name

Basic & Advanced Rietveld Refinement & Indexing Workshop

Start Date 1st Oct 2015
End Date 2nd Oct 2015
Description

Workshop Outline
Powder pattern Indexing and Rietveld structural refinement techniques are complementary and are often used to completely describe the structure of a material. Successful indexing of a powder pattern is considered strong evidence for phase purity. Indexing (with derived space group and lattice symmetry determinations) is considered a prelude to determining the crystal structure, and permits phase identification by lattice matching techniques. The Rietveld method is used to refine crystal structures and is perhaps best considered whole- pattern-fitting structure refinement, i.e., we must account not only for the crystal structure but also the instrumental resolution and diffraction physics effects (e.g., crystallite size and strain). The aim is to perform quantitative phase analysis and identification.

This workshop introduces the theory and formalisms of various indexing methods and structural refinement techniques. One unique aspect of this workshop is the extensive use of computer laboratory problem solving and exercises that teach method development in a hands-on environment.

We will use EXPGUI and GSAS for the Rietveld laboratory work; Crysfire (especially Dicvol, Ito and Treor) will be used for indexing exercises.

Lecture Components
Basic Crystallography

  • Emphasis on space groups, conventions, etc.

Powder Pattern Indexing

  • Data reduction methods for peak finding
  • We will use Dicvol 04, Treor and Ito indexing examples
  • Crysfire will also be discussed

Rietveld Structural Refinement

  • History and motivation for development of this technique
  • Qualitative description of various sample and instrument-related functions for profile shape, background, etc.
  • The use of least-squares constraints will be explored

LeBail and Pawley Fitting Procedures

  • What to do when atomic coordinates are not available
  • Discussion on use of these tools for structure determination
  • Use in powder pattern indexing

Computer Laboratory Components
Exercise problems will include:

  • Single phase indexing
  • Single phase refinement (all crystalline materials)
  • Multiphase refinement (all crystalline materials)
  • Nanophase, and small crystallite size content
  • Amorphous phase + crystalline phase(s)
Location Newtown Square, PA
United States
Contact
clinics@icdd.com
URL http://www.icdd.com/education/rietveld-workshop.htm
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Category Workshops
Topics Computing | Data analysis | General | Powder diffraction