n0.3-xMgx)Al0.3Fe1.7O4 (x=0.05, 0.1, 0.15, 0.2 and 0.25), prepared by
ceramic technique at 1000°C, were found to have cubic spinel structure. On
applying the full pattern fitting of Rietveld method using FullProf program,
exact coordinates of atoms, unit cell dimensions, atom occupation factors,
interatomic distances as well as crystallite size and residual microstrain have
been determined. It was found that the lattice parameter decreases with
increasing the Mg content, which may be attributed to the influence of the
difference between the ionic radius of Mg and Zn cations. Also, the variation of
the cation distribution has been discussed on the basis of site preference, size
and valence of the substituting cations. The low values of the isotropic
microstrain may be attributed to the method of the preparation in which the
samples after the last sintering were treated by annealing.