Improved cut-off frequency in Gd/La doped NiZnCo ferrites

Abstract

The rare earth doped NiZnCo ferrite ceramics were prepared by the sol–gel auto-combustion method. Pure spinel structure was obtained when rare earth content x ≤ 0.02. The first increase of lattice parameters of NiZnCo ferrite after adding rare earth metal implies that rare earth ions enter into the crystalline lattice. At the same time, the bulk density decreases and the porosity increases. The saturation magnetization (Ms) decreases slightly from 85 to 81 emu/g. Curie temperature (Tc) decreases slightly from 241 to 210℃ because of the weakening of the superexchange interaction between A-site and B-site. The initial permeability (μi) of samples changes little, but the cut-off frequency (fr) increases a lot. Small amounts of rare earth additions have positive impact on the magnetic behavior of NiZnCo ferrites, because the resonance cut-off frequency fr exceeds 300 MHz. Hence the rare earth doped ferrite materials find potential applications in high frequency side of electromagnetic spectrum.