Tuning magneto-dielectric properties of Co₂Z ferrites via Gd doping for high-frequency applications

Abstract

In present study, magneto-dielectric properties of Co2Z ferrite materials are tuned via Gd doping for application in high-frequency antennas and filters. Ba3Co2Fe24-xGdxO41 (x = 0.00, 0.05, 0.10, 0.15, and 0.20) materials are successfully prepared using solid-state method at 925 ℃ for 4 h with 2.5wt% Bi2O3 sintering aids. Different contents of Gd3+ ion affect micromorphology, grain size, bulk density, and magneto-dielectric properties of the ferrite. Upon increasing Gd3+ ion content, saturation magnetization (M S) first increases and then decreases. The maximum value of M S is 44.86 emu/g, which is obtained at x = 0.15. Additionally, sites occupied by Gd3+ ions can change magnetic anisotropy constant of the ferrite. Magnetocrystalline anisotropy constants (K 1) are derived from initial magnetization curve, and it is found that K 1 is related to spin–orbit coupling and intersublattice interactions between metal ions. Real part of magnetic permeability (μ') and real part of dielectric permittivity (ε') are measured in frequency range of 10 MHz–1 GHz. When x = 0.15, materials have excellent magnetodielectric properties (μ' ≈ 12.2 and ε' ≈ 17.61) as well as low magnetic loss (tanδ μ ≈ 0.03 @500 MHz) and dielectric loss (tanδ ε ≈ 0.04 @500 MHz). Results show that Gd-doped Co2Z ferrite materials have broad application prospects for use in multilayer filters and high-frequency antennas.