Improvement of Initial Permeability for Co₂Z Ferrite by Ti and Zn Substitution

Abstract

Ti-Zn substituted hexagonal ferrite samples Ba₃Co₂Ti_xZn_xFe_24-2xO₄₁ with 0<x<4 have been prepared by a conventional ceramic method. Ba₃Co₂Ti_xZn_xFe_24-2xO₄₁ with x=0 and 1 had a major phase of Z-type. However, other phases of M-type, Y-type, and spinel-type ferrites were observed for the samples with x=2 and 4. For the specimens with x=0 and 1, the initial permeability increased with an increase of the sintering temperature from 1250 to 1300°C. This may be attributed to the densification and the grain growth. For the specimens having x in the range from 0.0 to 1.0 sintered at 1250°C, the saturation magnetization was almost independent of x, the relative density took a maximum at x=0.85, and the coercivity had a minimum around x=0.85. Additionally, the maximum permeability of 24 was also attained at the composition. It was likely that these variations were related to the enhancement of the ferrite formation and densification with a partial substitution of Zn²⁺-Ti⁴⁺.