Re: [sdpd] Percentage crystallinity calculation using Powder XRD

[Armel Le Bail <alb...@cristal.org>]

>If you need to do the analysis without internal standard and no
>calibration curve you may look at:
>http://www.ing.unitn.it/~luttero/Publications/EPDIC_V/
>silicate_glass.html
>reference: Lutterotti et al., Mat. Sci. Forum, 1998, 278, 87-92.

OK Luca, but for that approach you need a very special
description of the amorphous component by some
highly defective crystalline model which can then be used
in a Rietveld refinement with extremely large diffraction
peaks, allowing quantitative analysis. Such a (controversial)
model was published for glassy SiO2 in the J. Non-Cryst. Solid
journal (the model is derived from cristobalite), but you cannot
find a lot of such models for other amorphous materials...
So that the method is not generally applicable. And
the controversial nature of this glassy SiO2 simple model may
lead to some problems with the reviewers when trying to publish
a manuscript (though the paper in J. Non-Cryst Solids was
welcome and really easy to publish - after rejection by
Nature and Science... in spite of a very good simultaneous
fit of the neutron and X-ray data of glassy SiO2 by the Rietveld
method ;-). Many "experts" dislike this approach...

Armel



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