Effects of co-dopants on the magnetic properties of Ni–Zn ferrites

In this study, substitution of co-dopants into the Ni_0.4Zn_0.6Fe₂O₄ ceramic was performed. Al³⁺, Sn⁴⁺ and Ti⁴⁺ ions were added to the Ni_0.4Zn_0.4Li_0.10Fe_2.10O₄ ceramic to improve magnetic properties. After sintering, all samples were indexed on a spinel structure and no detectable second phase was observed. When the concentration of dopants increased, the grain size of the Ni–Zn ferrites increased from 1.40 to 6.05 μm and the saturation magnetization declined from 428.8 emu/cm³ to 374.0 emu/cm³. Amongst the systems investigated, the Ni_0.4Zn_0.4Li_0.10Al_0.050Fe_2.050O₄, Ni_0.4Zn_0.425Li_0.10Ti_0.025Fe_2.050O₄, and Ni_0.4Zn_0.450Li_0.10Ti_0.050Fe_2.000O₄ ceramics revealed promising magnetic properties for applications. The measured initial permeability and quality factor were respectively 291.9 and 45.1 for the Ni_0.4Zn_0.4Li_0.10Al_0.050Fe_2.050O₄ ceramic, 316.9 and 42.5 for the Ni_0.4Zn_0.425Li_0.10Ti_0.025Fe_2.050O₄ ceramic, 429.4 and 34.8 for the Ni_0.4Zn_0.450Li_0.10Ti_0.050Fe_2.000O₄ ceramic. The high initial permeability and quality factor values associated with good electrical resistivity (>10⁶ Ω-cm) qualify the ceramics for high frequency applications. - Highlights: • Co-dopants Al³⁺–Li⁺, Sn⁴⁺–Li⁺, and Ti⁴–Li⁺ were substituted into Ni–Zn lattices. • Grain size of Ni–Zn ferrites grew from 1.40 to 6.05 μm with rising dopants content. • Saturation magnetization declined from 428.8 to 374.0 emu/cm³ with adding dopants. • Ni_0.4Zn_0.4Li_0.10Al_0.050Fe_2.050O₄ ceramic showed an μ_i of 291.9 and a Q_f of 45.1