Periclase is really problematic because of the small number of peaks in
the usual angular range used for QPA with Cu or Co radiation. Thus, the
particle statistics problem becomes extremely critic, as Pamela already
said. The uncertainties can be compared with the statistical intensity
errors
Hi,
I really wonder why do you bother about 1% difference when the error of
the method (XRD, quantitative phase analysis) could reach 10%
(absolute) ...
People in the discussions appearing here seem to forget about two things:
i) quantitative phase analysis done by rietveld method is always
Hi Lubo,
the difference between 6 and 7 % MgO is bigger than 15 % relatively,
thus the error by wrong re-scaling (e.g. if 10 % amorphous are
missing) is smaller than the error discussed. And, if the true content
of periclase should be about 5 %, than a measured value of 7 % is worth
to be
Hi Reinhard
Saying the words amorphous content and cement in the same breath is heresy in
many circles! Personally I think that it's a case of 'see no evil, hear no
evil'!
Anyway, many moons ago we did yet another study on the amorphous content in
clinkers/cements and they can vary alot - we
Another little nugget of information to chew on.
My other half (who just happens to be a cement chemist and the reason I've
worked on this 'orrible stuff!) tells me that most cement kilns have moved to
forced air cooling of the clinker these days - one of the effects apparently is
a reduced
Hi Pam,
maybe a misunderstanding: I did not try to discuss the amount of
amorphous material in cements. I'm aware of the problem, but a
careful Rietveld analysis with an internal standard should be able to
determine at least the magnitude of the amorphous part. Even if not
(e.g. if profile
Hi Rheinhard
The comments weren't aimed at you in particular! We've been banging our heads
against a brick wall about this stuff for some time, but not many in the cement
community seem to be listening.
Anyway - there is a fundamental statistics problem with quantifying minor
phases (of any
Hi all,
This is an interesting discussion of quantitative phase analysis. It sounds to
me from what Pam is saying that we can calculate an esd for each phase if we
know its particle size, and that the relative error would be larger for phases
in smaller abundance. If this is correct, then
Interesting thought and probably worth following up, although it sounds like a
meticulous and possibly time-consuming study for someone or other - any
volunteers? :-)
Following Deane Smith's methodology you should be able to calculate the number
of diffracting crystallites per phase for
