Dear Norberto,
to correct for preferred orientation, Toraya and Marumo seem to apply a
different correction function than the universally used one proposed by
Dollase. See Mineralogical Journal, 1980, 10, P 211-221. They succesfully
apply it to a monoclinic case study, but you may verify if
Dear Friends,
I am facing a problem in quantifying magnetite in a complex natural
mixture, using the conventional Rietveld method (in its quantitative
analysis approach). Apparently, the octahedral morphology of (difficult
to grind) magnetite crystals affects itd diffraction pattern.
To my
On 21/03/2014 10:59, Norberto Masciocchi wrote:
...
So, the question is:
Is there any way do get around this problem (without resorting to
spherical hamonics or to grind the specimen in a WC, SiC or BN mill)?
High energy X-rays or neutrons in transmission geometry would seem to help?
Best,
Norberto,
if the magnetite crystals in a natural sample are so big that you can
observe their octahedral morphology and this shape really gives rise to
any significant PO, than they are also definitely too big for any
quantitative XRPD phase analysis. Therefore, reducing the particle size
is
Hi Norberto,
just my two cents:
If you observe a discrepancy between observed and calculated intensities,
then it could also be that the calculated intensities are wrong.
Depending on the software you use for the Rietveld refinement, it may
happen that the wrong combination of space group
I am not sure if it is relevant for your case but in my work the reduction
of particle size by grinding is important to get adequate accuracy.
See the work P. S. Whitfield, L. D. Mitchell, The effects of particle
statistics on Rietveld analysis of cement Zeitschrift für Kristallographie
