Natale,
As far as I know, there is no way to constrain just one phase. As you've
found, if you do, the remaining scaling factors refine to their "correct"
values relative to the fixed scaling factor. Are you sure of the known wt.
%, i.e. is there any amorphous material present?
Ryan S. Winburn
Materials Characterization Lab.
Center for Main Group Chemistry
North Dakota State University
P.O. Box 5516
Fargo, ND 58105
Phone: 1-701-231-8341
Fax: 1-701-231-8831
E-mail: [EMAIL PROTECTED]
See our website @ http://qxrd.chem.ndsu.nodak.edu/
----- Original Message -----
From: Natale Perchiazzi <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, February 19, 1999 9:00 AM
Subject: GSAS help
>Dear All,
>I am trying to do quantitative analysis using GSAS. I have to analyze some
>mixtures with a known fraction of one phase. How can I constrain in GSAS
one
>phase fraction (weight %) to a given value, in the meantime allowing the
>remaining phase fractions to vary?
>I have unsuccessfully been trying with various starting values of the phase
>fraction, then switching off the refinement flag, but in the refinement the
>phase fractions always converge to the (almost) same wt % values, different
>(obviously, Murphy's?!) for the known phase from the expected value. Thanks
>in advance for your kind attention.
>Best Regards Natale Perchiazzi
>�����������������������������
> Natale Perchiazzi
> Dipartimento di Scienze della Terra
> Universit� degli Studi di Pisa
> Via S.Maria 53, I-56126 Pisa
> tel +39 050 847269
> fax +39 050 40976
> e-mail [EMAIL PROTECTED]
>�����������������������������
>
>
