Dear Leonid and others:
Let me comment on two points that were, I think, raised in your message: (i)
Whether to keep round-robin results anonymous or not; (ii) How "good" the
results actually are.
First of all, if anyone chooses to publish his own results on the Web or
otherwise, he/she, of course, has every right to do so. However, my firm
belief is that I cannot and should not do it for at least two reasons: The
first one is obvious; I don't want to put anyone in a position to be
(potentially) embarrassed. We had a variety of researchers with different
level of experience in line-broadening field (as it should be for a real
round robin) and I am particularly thankful to the participants who sent in
results, although it was their first time to evaluate size and strain from
diffraction data. Second reason: several participants were using commercial
software to evaluate size-strain values and/or were from companies that sell
XRD equipment or software. I can imagine a situation where a potential
customer could take these results (either good or bad, it does not matter)
into the consideration when making purchasing decision, which would be
unwarranted and a potential liability for the round-robin organizers.
Saying all this, I am not arguing that the individual results should be kept
secret. We hope to write a full publication where the individual results
will be, of course, available (or deposited with IUCr, depending on the
editor, I suppose). The report that was posted on the Web is just a
condensed (preliminary) version, as I understood from previous postings on
this mailing list that some people are eager to see the results as soon as
possible. I can also try to "extract" the original results from the e-mails
and post them on the Web page, but please, be patient; this takes some time
and according to my work plan, I can spend no more than 10 % of my time on
the round robin:-)
Next issue is about the results. I am asking myself the same thing: Most of
the people probably have expected less agreement in size-strain kind of
analysis, so "if results are so good, why did you undertake the round robin
in the first place?" :-) However, the full publication will hopefully give a
more balanced picture of overall results and then everyone will be able to
judge whether they are really "impressive" or not. For instance, in the
Conclusions it was pointed out that the mean was changed for 73 % if strain
was detected. Or even worse, if one considers the scatter of results in
domain-size values reported by the participants (among those included in the
averages reported on the Web site), say, of volume-weighted domain size:
minimum number reported to me was 21.1 and maximum 57.4! Now, I would call
that impressive but not exactly with the same connotation:-) However, I
think that this kind of scatter was expected. What was a nice result and
what, I believe, Leonid is referring to, is a comparison of averages
obtained by different methods and especially obtained by different
instruments. I believe that the reason for the former is absence of strain
and a simple specimen (cubic symmetry, spherical crystallites with isotropic
broadening) that was chosen. Some people objected to this, but I think that
was the only possibility to give the round robin a fair chance that results
won't be wildly different. Besides, more "difficult" sample would disqualify
most of the Fourier methods of analysis that could not be applied. The fact
that different instruments with very different resolutions gave similar
results for size and strain is particularly encouraging. Again, if a
specimen with smaller line broadening were selected, probably it would have
favored higher-resolution instruments, and the results might have been
vastly different.
The bottom line, as it looks to me, is: Yes, there was a substantial scatter
of results that we expected, but there is a nice agreement between different
instruments and methods, which is very encouraging. Especially interesting
is a comparison between different instruments because everything else was al
ready known from the literature. I hope this justifies why we tried to have
measurements collected on different instruments in the round robin, although
it might have been a problem for some participants.
Best regards,
Davor Balzar
******************************************************
National Institute of Standards and Technology
Materials Science and Engineering Laboratory
Div. 853, 325 Broadway
Boulder, CO 80305-3328
Tel: 303-497-3006
Fax: 303-497-5030
E-mail: [EMAIL PROTECTED]
Web: http://www.boulder.nist.gov/div853/balzar
European mirror:
http://www.ccp14.ac.uk/ccp/web-mirrors/balzar/div853/balzar/
******************************************************
-----Original Message-----
From: Leonid Solovyov [mailto:[EMAIL PROTECTED]]
Sent: Friday, April 13, 2001 11:14 PM
To: [EMAIL PROTECTED]
Subject: Re: Size/Strain Round Robin - 1st Report
Although my question is addressed to Davor Balzar,
I think that the question and the answer may also interest
other subscribers of SDPD and RIETVELD lists.
The First Phase results of the Size-Strain Round-Robin are really
impressive and I wonder, will it be possible to get acquainted with
techniques used by the participants and with values obtained?
Perhaps this would not be in contradiction with the round-robin
strategy
if, by authority of the participants, to put their reports in the
Internet.
This may allow more objective discussion of the results, which will
surely contribute both to the analysis of the First Phase and to the
2-nd
phase of the round-robin.
Following earlier suggestion of Armel Le Bail I have already posted my
report in the mailing list.
With this letter I have attached it in html format, which
can be read by Internet Explorer, Netscape and etc.
Leonid Solovyov
Contact address:
Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
K.Marx str. 42
660049, Krasnoyarsk
RUSSIA
E-mail: [EMAIL PROTECTED]
http://krsk.infotel.ru/icct/en/frames.htm
http://mesoporous.narod.ru/AboutUs/Solovyov/Solovyov.html
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