Effects of Zn substitution on high-frequency properties of Ba1.5Sr1.5Co2-xZnxFe22O41 hexaferrites

Ba_1.5Sr_1.5Co_2-xZn_xFe₂₂O₄₁(x = 0,0.4,0.8,1.2,1.6,2.0) hexaferrites substituted by Zn were prepared via conventional solid-state reaction. The influences of Zn substitution content on phase formation, microstructure, and magnetic properties, especially high-frequency magnetic properties, were systematically investigated. Results indicate that, when sintering temperature is 1200 °C, pure ferrite phase of Co₂Z is formed, and Zn²⁺ is successfully incorporated into the lattice. Appropriate amount of Zn substitution can improve the densification and saturation magnetization ($M_s$) of Z-type ferrite, thereby effectively promoting permeability. However, due to limitations of Snoek's law, cut-off frequency is found to be reduced with Zn substitution. For x = 0.4, the sample exhibits both high permeability (up to 22.49) and high cut-off frequency (~900 MHz), with Snoek constant $({\mu }_i?1)\times f_r$ reaching 19.337 GHz. Furthermore, magnetic loss for the sample with x = 0.4 is found to be low. It is anticipated that this material will have extensive application prospects for miniaturization and high frequency antenna applications.