Structure and enhanced electromagnetic properties of Y3+ substituted microwave sintered NiZnCo ferrites

Ni₀₆Zn_0.3Co_0.1Y_xFe_2-xO₄ ferrites (0 ≤ x ≤ 0.1) were fabricated by a sol–gel autocombustion method using Microwave Sintering Technology (MST) and Conventional Sintering Technology (CST). With increased Y³⁺ ions, the structure and electromagnetic performance of all MST samples were better than those of CST. In addition, the MST and CST samples formed a second phase (YFeO₃) when x > 0.025 because the radius of the Y³⁺ ion is larger than that of the Fe³⁺ ion. Compared with the CST samples, the MST samples showed increased densification and average grain size. Meanwhile, excellent electromagnetic performance of MST was achieved when the amount of Y substitution was 0.025, with high saturation magnetization (Ms, 154.19 emu/g), the lowest coercivity (Hc, 20.21 Oe), the lowest dielectric constant (ε′, 10.82@1 MHz), lower dielectric loss (tanδ, 0.0093@1 MHz) and the highest direct-current resistivity (ρ, 2.706 × 10⁶ Ω?m). These excellent results also confirm the good prospects of microwave sintering, which can better meet the needs of modern electronic devices for high frequency and low loss.