[sdpd] manganite-vacancies

[Guilhem DEZANNEAU <guilhemdezanneau...@yahoo.fr>]

i study manganite powders:these perovskite like
materials present the
peculiarity of presenting vacancies on both A and B
perovskite sites.


Since Debye-waller factors and occupancies are
strongly coupled it is impossible to refine both types
of parameters. I then decided to fix occupancies at
values in a given range (for example betwen 0.9 and 1
for A and B site) and then refined the B factors on
each site. I obtained a map of the Chi2 values as a
function of A and B site occupancies (it looks like a
valley). from this map, i can define a minimum line
which may correspond to the most probable B-site
occupancy for a given A-site occupancy.

Since i also have titration measurements, i can obtain
the lanthanum and manganese site occupancies that
agree better with titration results and that
correspond to a minimum in the Chi2 map.

The question is:
is this reasonment OK ? if not why ?

Thanks a lot


Guilhem DEZANNEAU
LMGP, domaine universitaire
BP46, 38402 SAINT MARTIN D'HERES

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