Thank you everyone. Yes, I am contemplating the rulette at this point :) ________________________________
From: Lubomir Smrcok [mailto:[EMAIL PROTECTED] Sent: Sat 3/15/2008 4:04 PM To: rietveld_l@ill.fr Subject: Re: Montmorillonite cif Just few words of warning : think of preferred orienatation in your samples... Moreover, from the vast majority of montmorilonites one gets only few so called "00L" diffractions what means that the results of quantitative phase analysis can be better obtained by a random numbers generator :-) Enjoy ! Lubo comparison with "calculated" patterns gives the numbers whose accuracy is not worth the time you spend with On Sat, 15 Mar 2008, Alan Hewat wrote: >> the cif-file below was created from the AMCSD... >> The I/Ic value calculated by Match! is 20.5 > >>> The only ICSD entry has an RIR of over 23, so does >>> vermiculite. Why is that so high? > > I guess these differences in I/Ic are not very significant, since the > exact same montmorillonite entry is in ICSD, from which you can export the > CIF directly. (In fact I doubt that there are any AMCSD entries that are > not also in ICSD). > > Clays, micas etc are highly layered structures, often with variable > amounts of intercalates, and usually not well ordered. They are therefore > difficult to model, so the profile fit will be relatively poor. > ______________________________________________ > Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE > <[EMAIL PROTECTED]> +33.476.98.41.68 > http://www.NeutronOptics.com/hewat > ______________________________________________ > >
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