Microstructure and magnetic properties of Y substituted M-type hexaferrite BaY_xFe_12−xO₁₉

Y (yttrium)-substituted M-type hexaferrite of composition BaY_xFe_12−xO₁₉ (x ranges from 0.1 to 0.8 with step of 0.1) was synthesized through ceramic process. Pure phase formation of M-type hexaferrite was confirmed by XRD patterns for prepared sample when x < 0.4. The second phase (Y₃Fe₅O₁₂) was detected when the substitution content exceeded 0.4. As the substitution dosage of yttrium increased, unconspicuous transform were observed in the microstructure of all samples BaFe_12−xY_xO₁₉, such as compactness, size of grain. The bulk densities (ρ) of the samples decreased first and then increased with the increase of X. It means that the compactness of the sample receded first and then enhanced with rise of Y³⁺ substitution contents. Moreover, with increase of Y³⁺ amount, Y³⁺ substituted the Fe³⁺ in the octahedral position of m-type barium ferrite, the saturation magnetization (M_s) of the sample decreases rapidly and obtained a minimum of 55.63 emu/g, and then increased gradually attributed to the appearance of the second phase (Y₃Fe₅O₁₂). Appropriate values of M_s (56.57 emu/g) and H_c (1794.17 O_e) were obtained simultaneously when x = 0.6. These two characters made the material suitable for the applications infield of magnetic recording.