Good day.
I've modified surface of my clay sample with iron. After the process my samples LOI in XRF analysis increased from 6.73% to 18.73%. Later, i've performed TGA analysis for this sample but weight loss was around 6%.
Can anyone please tell me that which one (LOI or TGA) is a more accurate indicator for the sample's thermal stability? And why the difference between two results are so high?
Thanks in advance.
Dear Osman Uygun ,
there are three aspects, which have to be considered:
a) Penetration depth of your 'surface modification with iron' in your sample;
it might be surface near in the range of a few µm; but I do not know, what you have really done.
b) Penetration/information depth of XRF analysis;
this mean value is in the range of up to a few 10µm*); thus covering the depth of your surface modification, but is not equal to the whole sample thickness.
c) Information depth of TGA; I think, this is equal to the complete thickness of your sample, which I suppose to be in the mm range. So with TGA you will get a result averaged over the whole sample. Any modification of the sample close to the surface will not significantly affect the averaged result.
You may share the sample thickness and the expected thickness of the modified surface layer...
*) strongly dependent on the atomic number and the x-ray attenuation of the host matrix; for low Z elements it will be in the very low µm range...
Best regards
G.M.
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