, the mixing of the standard ZnO and the sample powders
can cause problems like forming aggregates of the both materials. For
example, if larger aggregates of ZnO persist in the sample one can get
negative amorphous content because of the underestimation of the ZnO
by microabsorption. In contrast, coarse
: [EMAIL PROTECTED]
http://www.chem.umd.edu/facility/xray/
-Original Message-
From: Reinhard Kleeberg [mailto:[EMAIL PROTECTED]
Sent: Friday, November 16, 2007 3:14 AM
To: rietveld_l@ill.fr
Subject: Re: Amorphous content
We have positive experience with commercial ZnO pigments
For quantitative analysis the flat-plate transmission geometry is much
more preferable as it is free of the microadsorbtion problem. Of
course, resolution is not so easily achievable in this geometry, but
one may use synchrotron at last.
Best regards,
Leonid Solovyov
Thanks Reinhard and all for
Flat-plate transmission? Is this a good example of an oxymoron or am I missing
a trick here? Shome mishtake shurely.
Martin Vickers
Subject: RE: Amorphous content
Date: Fri, 16 Nov 2007 06:33:49 -0800
From: [EMAIL PROTECTED]
To: rietveld_l@ill.fr
For quantitative analysis the flat
Hi,
I am trying to determine amorphous content using Rietveld refinement and
internal standard. However resulting content of amorphous phase is really
unrealistic.
Moreover testing the method using standards with known amorphous content
does not clarify the situation. For example ZnO (NIST, 95
At first glance it looks like a classic microabsorption problem, but I
don't have the linear absorption coefficients to hand. Using an
internal standard with a too small absorption will tend to over-estimate
the amorphous content. Ce versus Zn is a pretty big contrast for CuKa,
even
