MAGNETIC AND MOSSBAUER STUDIES OF TI4+-SUBSTITUTED SOFT MN-ZN FERRITES

The present work reports the magnetic properties and Mossbauer spectra of soft ferrites MnaZnbFe1-a-b2+Fe23+O4 with Ti4+ substitutions. The addition of Ti4+ to manganese-zinc ferrites induces considerable improvements of properties such as the linear dependence of permeability versus temperature, and small disaccommodation of the permeability. Samples with Mn0.57Zn0.34Fe0.09+x2+TixFe2-2x3+O4 composition (where x = 0.00, 0.02, 0.04, 0.06, 0.08, 1.00) were prepared by the usual ceramic technology. The presence of Ti ions strongly influences the magnetic anisotropy, as evidenced by the temperature dependence of the permeability. A sublattice assigned to Ti4+Fe2+ pairs appeared in the Mossbauer spectra, which also gave information on the local surroundings of iron ions. The appearance of a secondary maximum of permeability (SMP) at negative temperatures or a constant slope over a wide temperature range is typical for mu(i)(t) curves. Increasing Ti4+ contents shift the SMP to higher temperatures because of a positive contribution to K1 of the Ti4+Fe2+ pairs at octahedral sites, in agreement with the hyperfine magnetic fields observed for ferrites with large titanium substitutions.