| BaxTi03 prepared through coprecipitation method may contain
vacancies in either Ba-position or Ti-position. Since by chemical
analysis it has been ascertained that the mole content of Ti-ion is
in excess of that required to maintain the stoichiometric ratio of
Ba : Ti as 1 : 1 it is assumed that there occur vacancies in
Ba-position in the structure of BaTi03• On this assumption, when
exact positional coordinates in the lattice structure, P,mm• are
determined on refinement of X-ray intensity data with respect to
the calculated intensities, it is found that more agreeable results
are obtained when atomic positions in the lattice structure are such
that a certain portion of Ba-positions is lying vacant than when
the ratio of Ba : Ti is 1 : 1.
In this paper, the methodology adopted for structure refinement
from powder diffraction data will be discussed at length, focussing
on the various assumptions that are required to be made to simplify
the procedure. |
