Profex XRD: Background refinement

[@srk21994]

it's like when I have any doubts I got the exact tutorial. Thanks a lot for the efforts in these tutorials and every new feature in the updates.

[@Lilhobis]

great video, thanks!

[@mohamedoraby8044]

How to push the background up at specific parts of the curve to fit every thing for better X2?

[@qmtv5772]

how to subtract the background contribution caused by the instrument?

[@nunya8701]

Asome

[@nunya8701]

Also face revale asome

[@ZZZZzzzcccc]

Hi Sir. Thank you for your tutorials. May I ask you a question? Where can I find the scale factor in Profex? I tried to find it and increase the absolute intensity of some peaks however cannot find it in the manual. Thank you! Looking forward to your reply!

[@profextutorials2325]

The scale factor is the GEWICHT parameter. It is not the Rietveld scale factor, though, because it is already corrected for the unit cell density: GEWICHT is equivalent to S*(Z*M*V)

[@honkola999]

thx for the video!! We have issues with smectite/illite peaks at about 5,7 2Theta (deg). The background is often way to low or the for the following peaks, such as the 8,7 2Theta (deg.) illite peak. The Problem might also come from unfitting smectite structure files. We have tried the montmorillonite str. files as a substitute for the smectite file, which is also not a good solution.

[@profextutorials2325]

It is difficult to guess what the problem is without seeing the data. It could be because the measured low angle peak is actually smaller than it should be, for example because the automatic divergence slit is inaccurate, or because the beam spills over the sample. At very low angles instrument alignment is more critical than at high angles. So you should check if the modelled peak is too strong, or the measured peak is too weak. It could be one or the other. The former must be fixed in the refinement, the latter in the hardware/sample. Either way, the too strong model peak pushes the background down. Once the peak intensity is correct, the background will fit well, too. Here are some tips for accurate low angle peaks: - make sure your sample surface is perfectly centered in the center of the goniometer (no height error) - maybe use a fix divergence slit. Not the automatic one set to fix mode, but really insert a fix slit. They are more precise - make sure that the sample dimensions in the Profex instrument configuration are entered correctly

[@honkola999]

@@profextutorials2325 Thanks a lot!! Its working way better now. Although, we don't have any other chance but to work with the automatic slit in fixed mode and an additional one (behind the automatic one) with the same size.