Ultralow dielectric constant nickel–zinc ferrites using microwave sintering

Ultralow dielectric constant values were measured on Ni–Zn ferrites prepared using Fe₂O₃ as a starting material and sintered in a microwave field. Significant differences in microstructure, magnetic, and dielectric properties were observed between microwave-sintered Ni–Zn ferrites prepared using Fe₃O₄ (T34) and those starting with Fe₂O₃ (T23) ingredients. Higher magnetization values observed in T23 ferrite are attributed to large grain size, possibly containing abundant domain walls and the presence of fewer Fe²⁺ ions. The ultralow dielectric constant values observed on T23 ferrites show that this procedure is highly suitable to prepare Ni–Zn ferrites for high-frequency switching applications.