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

Abstract
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, T_k/µ_i 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 Mn_0.51Zn_0.43Fe²⁺_0.06Fe₂O₄, by adequate reduction of Zn²⁺ content. The magnetic and electric properties improve : d.c. electrical resistivity increases while the loss factor tanδ/µ_i and disaccommodation decrease. By addition of 0.35% by weight TiO₂, the initial permeability, at 20°C, improves. We remark the flattening of µ_i(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 T_c. Structural and magnetic properties of high permeability ferrite with substitution of titanium ions confirm that Ti⁴⁺ ions make pairs with Fe²⁺ ions. [4,6].