Effects of Ca-Zr co-substitution on cation site occupancy and electromagnetic properties of YIG garnet ferrite with narrow ferromagnetic resonance linewidth

YIG garnet ferrite is considered a crucial material for microwave components such as circulators, which is expected to have a low ferromagnetic resonance (FMR) linewidth to reduce insertion loss. In this work, Ca-Zr co-substituted Y_3-xCa_xFe_5-xZr_xO₁₂ (0.00 ≤ x ≤ 0.75, ∆x = 0.15) ferrites were fabricated and the microstructure as well as electromagnetic properties were thoroughly investigated. The results showed that moderate substitution improved the microstructure, decreased the coercivity and the FMR linewidth, and increased both the saturation magnetization and the resistivity. In particular, the cation site occupancy and FMR linewidth separation calculation were thoroughly examined. The best overall performance of YIG garnet ferrite was obtained at substitution x = 0.45, with a density of 4.988 ± 0.006 g/cm³, FMR linewidth of 27.85 ± 1.40 Oe, coercivity of 1.66 Oe, saturation magnetization of 1818 Gs and DC resistivity of 8.93 × 10⁶ ± 2.28 × 10⁶ Ω•m. The Ca-Zr co-substituted YIG garnet ferrite displays outstanding overall performance and promising potential for incorporation into microwave component designs.