Effect of ZrO₂ addition on the microstructure and electromagnetic properties of YIG

In this work, we reported the microstructure and electromagnetic properties of a series of zirconium substituted yttrium iron garnet ferrites (YCaZrIG) with iron deficiency composition of Y_3-xCa_xZr _xFe_4.93-xO₁₂ (x = 0.1, 0.2, 0.3, and 0.4, with electrostatic balance by Ca²⁺ substituted for Y³⁺ ions) prepared by a solid-reaction method. The addition of ZrO₂ shows no obvious influence on the phase, density and dielectric constant of YIG ferrites. When Zr addition x ≤ 0.3, the substitution of Zr⁴⁺ for Fe ³⁺ decreases the amount of Fe ions, increases the lattice parameter and enhances the grain growth of garnet phase. The solubility of zirconium in YCaZrIG ferrite was found to be approximately 0.3, above which excess ZrO ₂ would lead to the precipitation of a second phase inside the YCaZrIG ferrite. This would inhibit the grain growth of garnet phase and cause an increase in the dielectric loss and coercivity. The observed reduce for saturation magnetization when x = 0.4 is possibly due to antiparallel alignment of magnetic moment of Fe³⁺ in the d site caused by the decrease of a-d exchange interaction. Additionally, we got the optimum electromagnetic properties in the samples with x = 0.3: ε_r = 14.1, tan δ_e = 2.5 × 10^-4, H_c = 47 A/m, 4πM_s = 1936 × 10^-4T, ΔH = 7.1 KA/m.