Hi,
I pointed out that each model needs to be tested and their plausibility
determined. This can be achieved by employing Bayesian analysis, which takes
into account the diffraction data and underlying physics.
I have carried out exactly same analysis for the round robin CeO2 sample for
both size distributions using lognormal and gamma distribution functions, and
similarly for dislocations: screw, edge and mixed. The plausibility of each
model was quantified using Bayesian analysis, where the probability of each
model was determined, from which the model with the greatest probability was
selected. This approach takes into account the assumptions of each model,
parameters, uncertainties, instrumental and noise effects etc. See Sivia
(1996)Data Analysis: A Bayesian Tutorial (Oxford Science Publications).
Best wishes,
Nick
Dr Nicholas Armstrong
NIST-UTS Research Fellow
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(in USA) NIST, Ceramics Division
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----- Original Message -----
From: Nicolae Popa <[EMAIL PROTECTED]>
Date: Saturday, March 26, 2005 8:05 pm
> Hi,
> But the diffraction alone cannot determine uniquely the physical
> model. An
> example at hand: the CeO2 pattern from round-robin can be equally well
> described by two different size distributions, lognormal and gamma
> and by
> any linear combinations of these two distributions. Is the situation
> different with the strain profile caused by different types of
> dislocations,possible mixed?
>
> Best wishes,
> Nicolae Popa
>
>
>
> > Best approach is to develop physical models for the line profile
> broadening and test them for their plausibility i.e. model selection.
> >
> > Good luck.
> >
> > Best Regards, Nick
> >
> >
> > Dr Nicholas Armstrong
>
>
>
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