Influence of Small Addition of Ti4+ Ions on the Properties of High Permeability Ferrite

Mn-Zn ferrites substituted with Ti4+ ions are now becoming commercially important. The substitution with titanium ions in Mn-Zn ferrite is recommended for ferrites with low losses and low temperature factor of initial permeability, Tk/µi because of the shift of the secondary maximum of permeability, SMP, towards lower temperatures [1] and the increase of the d.c. resistivity [3,4,5]. The present paper reports the results obtained by substitution of a small amount of titamium ions to high permeability ferrite Mn0.51Zn0.43Fe2+0.06Fe2O4, by adequate reduction of Zn2+ content. The magnetic and electric properties improve : d.c. electrical resistivity increases while the loss factor tanδ/µi and disaccommodation decrease. By addition of 0.35% by weight TiO2, the initial permeability, at 20°C, improves. We remark the flattening of µi(T) curves with the increase of content of Ti4+ ions and the diminution of the peak at the Curie point, facts that can be associated with two points of anisotropy compensation instead of one, the second minimum of K1 being in the neighborhood of Tc. Structural and magnetic properties of high permeability ferrite with substitution of titanium ions confirm that Ti4+ ions make pairs with Fe2+ ions. [4,6]