Hello, Due to project internal reasons I can only obtain samples (multi-oxide systems) having a volume being to small for a quantitave XRD analysis. Is it correct to fill up the sample with a known crystalline, or an amorphous powder in order to increase the volume? Is there any other method to get a quantitative phase content?
Thank you in advance,
Regards Bernd
Dear Bernd Dittert ,
Yes, it is possible to get good results in principle; it will strongly depend on the original sample.
The first option is to use an inner sample holder inside the available one, with a much lower sample filling space; it could be made of plexiglass, amorphous cellulose, glass, and more high technological material such as SiC, which has a small number of peaks at the X-ray.
The second one is the possibility of filling up the excess space with NaCl, easily eliminated afterward by just adding water, recovering the original sample.
Another useful technic is to spread an emulsion (sample + isopropyl alcohol or acetone) all over an planar amorphous solid sample holder (there are some polymers sample holders completely amorphous at X-ray analysis).
It will generate a sort of film, that depending on the thickness, can be analyzed by normal or a razing angle setup.
Finally, it is not strictly necessary to fulfill all space in a regular sample hold. The X-ray beam hits the center of the sample holder; if the small amount of sample is precisely allocated at the center, depending on the slits used to control the beam's divergence, a tiny amount or none of the sample holder will be illuminated by the beam.
Best regards,
WNM
Dear Wagner Da Nova Mussel,
thank you very much for your helpful answer!
Best regards BJD
Dear
The addition of an amorphous component is not a very good alternative, it leads to background deformations in the record.
And what is a small amount, mm ^ 3 or less? It is best to disperse the sample in some medium (acetone, ethanol) on a low-background sample holder. Special single crystal Si holders are used. The critical operation is rather homogenization.
adding a known crystalline would be a better choice than amorphous powder.
Dear Dalibor,
yes the samples have a volume of about 1 mm^3. Thank you for your helpful answer.
Sincerely Bernd
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