This exercise provides a tutorial example of how to use the GSAS software package with the EXPGUI interface to perform Rietveld analysis. The following pages show how to use EXPGUI to perform the same tutorial refinement for Nickel powder, presented in the GSAS manual. The GSAS manual is included with the distributions of the GSAS programs (see above). The manual can be found EXPGUI website.

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Another possibility with the background is to estimate it by linear interpolation between selected points between peaks and then subtracted. EXP does not exist. At the end of the Rietveld process, the refined phase fractions are converted into weight fractions and rescaled to the values of the original mixture by the ratio between the refined Xs,c and the known Xs amount of added standard.

The glass amorphous fraction must be determined indirectly with the aid of an internal standard Gualtieri, Sample selection and preparation The example reported here is a full description of a Rietveld refinement using EXPGUI for the determination of the phase weights in a polyphasic mixture containing an amorphous phase. Common commands that can be used include the following insert them into space next to ‘DO’ button and click ‘DO’ to action these commands: Executable versions of GSAS are distributed more-or-less freely but the source code is not distributed.

Nonetheless, I agree with McCusker et al. Another possibility with the background is to estimate it by linear interpolation between selected points ezpgui peaks and then subtracted. Click the plot tab and select the files you want plotted exxpgui you can use Ctrl to select specific ones.


In the Histogram menu, add more terms to the background function: It is time now to define a background function and prepare it for the refinement.

Play with these concepts and see what happens. For a Rietveld refinement, it is essential ezpgui the powder data is properly collected. In the example, the phases are known a priory but that was just a test case! Remember to change 1 or a couple of things and refine and probably allow only small changes – damping to 8 or 9.

The final result with stadard deviation is: Run powpref first and genles. DATan ascii file which contains the wavelength of the experiment and other information such as polarization factor.

The manual is what you should cite when publishing expui structure refined with GSAS [and of course you will cite it: Then click ‘powpref’ to load above changes and ‘genles’ to run the refinement and liveplot to see what is happening.

Programs (downloads, links and basic instructions)

From the Options menu, first select Auto locate and then Phase 1 for which you will unflag the use of dashed lines and flag the use of show reflections. Since this correction should be the same for both the phases in a homogeneous powder, you have to set an hard contraint so to refine the same exptui for both the phases.

Further tutorials and information on GSAS can be found on: GSAS General Structure Analysis System is a comprehensive system for the refinement of structural models to both x-ray and neutron diffraction data. Repeat the same for the oxygen atom O at 0. These tutorials are intended to be read in parallel with the GSAS manual. In Mineralogy 20, This is a method to remove or minimise the curvature of peaks in the collected diffraction patterns. Origin, arguably produces the best figures for publications and reports e.


Programs (downloads, links and basic instructions) | UNSW Chemistry

EXPGUI automatically goes to the last cycle of refinement and highlight the lines with the agreement factors. Expugi collection Prior to the quantitative phase analysis one is generally sopposed to have a preliminary qualitative phase analysis in order to determine: You can change the numbers to give the section of the detector you want.

De La Torre, A. DAT are available upon request from the author. If W3 only had one collection in it will give expyui 1D diffraction pattern or a conventional diffraction pattern. Modern Powder Diffraction Rev. De La Torre, A. The Preferences menu The Help menu gives you access to the “about box” of Fox, and you can toggle the use of tooltips. Skip to main content. To my experience ,when there is just one preferred orientation direction it is better and safer to manusl the MD model because the SH model gives a better fit but the physical meaning can be lost if too many coefficients of the polynomial are manaul.

Click on the Profile menu and change the type of the profile function of both phases Change Type. Although this is addressed to the beginner, it is strongly encouraged to time some time to read the milestones papers by McCusker et al. Structure models can be taken from crystal structure databases such as ICSD see http: There are other codes e.