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Tutorial Synchy2o3

Y2O3 – Synchrotron Data

Files needed: y2o3_id31.xye; y2o3.cif

Learning outcomes: This tutorial shows refinement of a sample of Y2O3 collected at id31. Note the sharpness of the reflections and that we still see strong reflections out to d=0.48 Angstroms.

1. Save the data file in your working directory.

2. Go through the menu for a Simple Rietveld refinement. For the instrument select “synchrotron”. The wavelength was 0.733640 Angstroms. Use 90 for the LP Factor. In the wavelength line you’ll see that lh has been set to 0. This assumes there’s no “emission profile” contribution to line broadening.

3. You might find it easiest to start the refinement by on analysing data up to e.g. 20 degrees. You might find you need to play with peak shape parameters to get a reasonable starting model for peak shapes.

4. Instead of the “default” TCHz peak shape you might want to try the lines below which use a full Voigt function rather than a pseudo-voigt:

prm pr1 0.00676` min 0
prm pr2 0.00682` min 0
prm pr3 0.00731` min 0
prm pr4 0.00809` min 0

lor_fwhm = pr1 Tan(Th) + pr2/Cos(Th) ;
gauss_fwhm = pr3 Tan(Th) + pr4/Cos(Th) ;

5. You should be able to get Rwp around 9% from 7 to 98 degrees 2-theta.