Rietveld Structure Refinement

 

The Rietveld method is widely recognized to be uniquely valuable for structural analysis of nearly all classes of crystalline materials not available as single crystals. The method was first reported at the Seventh Congress of the IUCr in Moscow in 1966. It was 10 years after the first paper of Rietveld in 1967 that the full importance of this technique was realized.  In 1980's the number of application papers rapidly expanded with nearly 500 papers where the Rietveld method was used being published in 1989. During the same period refined Rietveld phase scales began to be used to quantify phases in mineral samples, a development of great significance to the mineral industry for process and quality control of raw materials and products.  Today, Rietveld refinement is an essential tool for research and industrial applications for solid state studies in mineralogy, materials, and pharmaceutical industry.

 

Standard report (even though there is no such thing as a standard structure refinement problem) of Rietveld structure refinement includes the following:

  • Sample preparation for diffraction experiment

  • Experimental conditions

  • Diffraction raw data file in original and ASCII formats

  • Final Rietveld plot

  • Table of crystallographic data

  • Coordinates of atoms and isotropic thermal displacement factors

  • Figure - asymmetric unit with atoms labeling scheme

  • Figure - polyhedral representation of the structure

 

EXAMPLE OF STANDARD REPORT

Rietveld structure refinement Report

 

1. Sample Preparation:

One gram of dry sample was hand-pulverized  and 1μm fraction separated with a microsieve  was used for data collection.

 

2. Experimental Conditions:

Part of pulverized sample was top-loaded into the standard glass sample holder (18mm height and 0.8 mm depth), and compacted with a class slide. Data collection was performed using horizontal goniometer Rigaku DMAX-B powder diffractometer with diffracted beam graphite monochromator. Slits DS=1, SS=1, RS=0.15. Two theta angular range=5-80, Step size=0.05, Step time=5 sec.

 

3. Diffraction data file

Diffraction data file in Binary (Z000111.raw), ASCII (A000111.raw) and MS Excel (X,Y) formats are in CD

 

4. Final Rietveld plot

 

 

5. Conditions of X-ray data collection and Refinement for Na4[(TiO)4(SiO4)3 6H2O in Space Group R3m

                                            

6. Coordinates of atoms and isotropic thermal displacement factors

 

 

7. Figure - asymmetric unit with atoms labeling scheme

 

8. Figure - polyhedral representation of the structure

 

 

 

 

 

 

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