[sdpd] nanocrystallites+Instr.Resolution

["Guilhem Dezanneau" <gdezano...@inpg.fr>]

Hi,

i actually work on structure refinement (fullprof ) on nanocrystalline lanthanum manganites powders.

I would like to take into account the crystallite size directly in my fullprof refinement because if i let

vary the U,V,W..parameters, it seems very difficult to keep them stable when varying other parameters.

So, i tried to determine the Gaussian and Lorentzian contributions to instrument resolution on LaB6

but many programs of peak shape function analysis use the pseudo-voigt function (and not voigt) which gives

the same value for both contributions.

Nowadays i try to fitt LaB6 peaks with a Pearson VII function which seems to work better than PV and then i will try to convoluate

it with a Gaussian and then with a Lorentzian function to extract the Two FWHM(G) and FWHM(L) contributions.

My question is:

Am i doing well ? or are there programs that allow to fit peaks with voigt function, with Ka1 and Ka2, and a knwon ratio between the two

wavelengths ?