Re: [sdpd] Comparision of the intensities

[Armel Le Bail <armel.le_bail...@univ-lemans.fr>]

Hi,

 >1) How can instrumental broadening be determined.

Recurrent question...

You could find many anwers at the Rietveld mailing
list archive :
http://www.cristal.org/forum/rietveld_l/index.html
http://www.mail-archive.com/rietveld_l...@ill.fr/

Apparently you are not working with a synchrotron,
otherwise I would have suggested NAC as a standard
(giving narrowest linewidth than LaB6).

Working with a laboratory instrument, this is generally
the contrary (Lab6 giving narrowest linewidth than NAC).
The reason being penetration depth, non-parallel beam,
etc.

You have to realize that depending on the recording
conditions on a lab instrument, the peak width may
change a lot for the same sample... Generally a
packed sample will have narrowest linewidths than
a sample dusted through a sive...

So, the more general answer to you question is :
Use the appropriate reference compound,
and record the data under appropriate conditions...
To you to decide depending on your own problem
and recording conditions... NIST certainly does not
agree with this statement : a reasonable reference can
be the same compound well recrystallized, if you can
make it : all the geometrically sample dependent
broadening effects will then be the same if both
measurements (reference and size-strain broadened
samples) are realized in the same conditions (if lab
instrument) of packing and thickness.

The problem with "instrumental line broadening"
when dealing with a lab instrument is that there is also
a part coming from the sample itself (broadening due to
packing, absorption, etc)...

Best wishes,

Armel


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