[GSAS-II] GSAS-II Digest, Vol 291, Issue 1

[LiaoNU]

Adam,

Thank you and several others, especially Bob and Wenqian, who provided
useful information. It turns out, to my best of understanding, the phase
fraction refers to mole fraction, or number of unit cells. The
weight fraction is then derived based on cell volume.

My data was collected at the APS at Argonne, which ran non-top off mode,
meaning at certain times of a day the beam intensity deeply increases as a
result of ring refill. The absolute value of phase fraction may be
influenced, but the weight fraction, on the other hand, has some
normalization calculation thus is not influenced.

Thank you all again.

Best,
Yifeng

On Fri, Feb 19, 2021 at 11:52 AM Creuziger, Adam Abel (Fed) via GSAS-II <
gsas-ii at aps.anl.gov> wrote:

> Re Yifeng:
>
> I am not sure on exactly what units are for "phase fraction”, but looking
> athletic GSASIIpwd.py it looks like this is the scale of the histogram for
> this phase. That can get a little convoluted with the Histogram Scale
> Factor in sample parameters.  You can set a constraint for this if you have
> multiple phases (constraints-> histogram/phase -> ‘Scale’   I end up with
> 0:0:Scale+1:0:Scale=1 as the equation)
>
> The weight. fraction includes the atomic weight (including occupancy)
> divided by the unit cell volume. I found this description on line 132 of
> GSASIIddataGUI.py.
>
> For exporting, Export-> Powder data as-> Text file  worked to some
> extent.  I’ve also been using the scripting toolkit, and that works well.
>
> ____________________________
> Dr. Adam Creuziger
> National Institute of Standards and Technology (NIST)
> Gaithersburg, MD USA 20899.8553
> Office 301-975-6015
> adam.creuziger at nist.gov
>
> Visiting Research Affiliate Faculty, Metallurgical and
> Materials Engineering. Colorado School of Mines
>
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