HRPT data refinements

Any of the commonly used Rietveld refinement programs may equivalently well be used to treat the data from HRPT. The most popular programs (Fullprof, GSAS, Jana, etc.) will produce equivalent results for the refined parameters and agreement factors, provided all relevant corrections are applied in a proper way. 

A serious point to consider is that in the HRPT data, the esd's of the measured intensities are not necessarily equal to the square-roots of the intensities. In order for the Rietveld codes to work properly, it is therefore of high importance that the esd's for the measured intensities are supplied and properly understood by the corresponding program. The reason behind is the weighting scheme for the points in the profile that will be applied in the refinement: the weights assigned to the points in the profile are calculated from the errors of the measured intensities. Our data by default will be supplied in the format #8 for Fullprof, and thus readily contain the explicitly supplied correct esd values for all measured intensities in the profile. Should you require it, a set of very simple and fast conversion routines will transform all your data to other relevant formats, for example: 
- an .xye format (3-columns data: 2Theta, I, esd(I)); to do so, give a command > hrpt-col-all in the directory containing your data, or 
- an "ESD" format for GSAS; to do so, give a command > hrpt-gsas-all in the directory containing your data, etc. 

In the table below, we have collected the sets of profile parameters to start with, for some of the most common modes of HRPT. The profile parameters will generally depend on: the wavelnegth, the resolution mode used, the sample diameter (but also height..), and the radial collimator used. It is hardly possible to collect absolutely all possible settings, so just look for your exact wavelength and for the further conditions possibly most similar to those you were using, in order to get a good set of starting profile parameters for your refinement. In case your subject of interest is the exact determination of the microstructure parameters (microstrain- or size-related broadening), and its possible quantification, we advise you to re-measure the instrument resolution function with your exact experimental conditions, during your experiment, or even to mix the standard sample with your powder.