XRD having an accuracy of 0.01 nm = 0.1 Å? Which quantity to you imply to be measured??? A lattice parameter? An average interatomic distance? An individual interatomic distance? A crystalllite size from Scherrer broadening? The thickness of a layer by GIXRD of a multilayer?

A crystalllite size from Scherrer broadening...Professor

Dear Mathu Sridharpanday ,

as Andreas Leineweber pointed out, 0,01nm is 0,1 A and that is about about 1/10 of atomic diameter.

When focussing on the crystallite size there are various parameters, which enter the determination of the crystallite size*) via Scherrer broadening.

Apart from the Scherrer formula, in which the shape factor **) significantly scales the resulting mean crystallite size value, the peak width (entering the Scherrer formula) is a very critical parameter, which does not only depend on the crystallite size.

For details of crystallite size determination you may have a look at the presentation of Scott A. Speakman as attached below.

So in consequence with repect to the precision (or better uncertainty) of the calculated crystallite size value you should add, to my opinion, a minimum error for the estimation of that value of at least about 10%; and that is far away from 0,1A.

*) crystallite size via Scherrer formula will give you an estimate of the crystallite size as some kind of mean value.

**) shape factor as a rough scaling parameter is depending on the geometry of the crystallites

ok. I already started to write, but there is nothing to add

Sorry Andreas Leineweber ,

for having been too fast...

But Mathus's answer with respect to crystallite size dares for a quick answer...

No problem at all. Actually I wanted to indicate that it needs some consideration what the "crystallite size" values imply, which we extract from analysis of the Scherrer broadening (some average value representative for the crystallite size distribution). In this sence an "accuracy" of 0.01 nm is meaningless, even if a stupid code seems to imply such an error.