Moessbauer and FT-IR studies on non-stoichiometric barium hexaferrites

The site occupation of the cations in non-stoichiometric Ni-Zr substituted barium ferrite BaFe sub(12-2x)Ni sub(0.63x)Zr sub(0.50x)O sub(19- delta ) (0 less than or equal to x less than or equal to 0.5) has been investigated using Moessbauer and FT-IR spectroscopy to examine its influence on magnetic properties ( sigma sub(s), T sub(c), K sub(1), etc.). It is observed that maximum substitution of Zr occurs in the 2b and 4f sub(1) sites for small values of x (x approximately 0.1). Ni substitutes Fe on the 4f sub(2) site but, for larger x it mostly occupies the 12k site. The variations of isomer shift, hyperfine field and quadrupole splitting with substitution are related to changes in lattice constant, grain size and site occupancy of substituted ions.