Why Powder material for XRD test should be passing the 75 μm sieve? The different grain size distributions of powder materials can affect the phase composition derived from the signal?
Hossein Aslani
Check this 2 different in particle statistic in 2D detector.
It is to have just enough particles in the x-ray interaction volume of your XRD set up in order to have a nearly homogenous distribution of crystallites in angular space. Otherwise you may suffer from orientational artifacts, which will lead to variations in peak heights compared to the ideal case. Errors in peak heights will lead to errors in phase composition derived from XRD.
Hossein Aslani
Check this 2 different in particle statistic in 2D detector.
Dear Dr. Maykel Manawan
Thank you so much
please explain about pictures
Could the Powder material that passing the 45-μm have a better result than passing the 75-μm sieve?
Dear Dr. Gerhard Martens
Thank you so much
Could the Powder material that passing the 45-μm have a better result than passing the 75-μm sieve?
The images provided by @Maykel show the effect quite well: too less particles will give no homogenous angular distribution.
I think up to 45µm particles will give similar results compared to 75µm sieved ones.
Prof. Hossein Aslani , Yes, as explained by Prof Gerhard Martens , the top picture is the coarse grain while the bottom is fine grain. The coarse grain give you sort of texture/preferred-orientation like effect but more complex.
For 0D or 1D detector the scan will be inside the blue arrow. If you use a static sample holder and you rotate your sample a few degree such in that picture, you will give a different intensity. Most modern machine equipped with rotating sample stage, but the result it not as good as small and homogeneous particle statistic.
Here is the example of texture or preferred-orientation (not from the picture above). It give a different intensity for the same sample.
Texture or preferred orientation are easy to handle because it can be modeled (March/Dollase or Harmonic or WIMV etc), but not graininess.
Dear Dr. Maykel Manawan
Thank you very much, The explanations were very good
good luck
and even 75 um particles are too coarse.
In a derivation by Deane Smith, he showed that if you have a sample of 40 um size particles, of the ~10^5 particles you have in the diffracting volume, only ~12 will actually diffraction. You need to get down to 4 um particles, which will give you ~12000 particles diffracting. Even 10 um particles will only have ~760 particles diffracting.
It's all about reproducible intensities. If you need reproducible intensities to about ~1% relative, you need ~4-5 um particles.
Dear Dr. Matthew R. Rowles
Thank you very much for the comment.
Deane Smith, who is author of Book "Industrial applications of X-ray diffraction"?
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