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

Abstract

Magneto–dielectric properties of Co2Z ferrite materials are tuned via Gd doping for applications in high-frequency antennas and filters in the present work. Ba3Co2Fe24−x Gd x O41 (x = 0.00, 0.05, 0.10, 0.15, and 0.20) materials are successfully prepared by using solid-state method at 925 °C for 4 h with 2.5-wt% Bi2O3 sintering aids. The content of Gd3+ ion can affect micromorphology, grain size, bulk density, and magneto–dielectric properties of the ferrite. With Gd3+ ion content increasing, saturation magnetization (M s) first increases and then decreases. The maximum value of M s is 44.86 emu/g at x = 0.15. Additionally, sites occupied by Gd3+ ions can change magnetic anisotropy constant of the ferrite. Magnetocrystalline anisotropy constant (K 1) is derived from initial magnetization curve, and found to be related to spin–orbit coupling and intersublattice interactions between metal ions. The real part of magnetic permeability (μʹ) and real part of dielectric permittivity (εʹ) are measured in a frequency range of 10 MHz–1 GHz. When x = 0.15, material has excellent magneto–dielectric properties (μ′ ≈ 12.2 and ε′ ≈ 17.61), low magnetic loss (tan δμ ≈ 0.03 at 500 MHz), and dielectric loss (tan δε ≈ 0.04 at 500 MHz). The results show that Gd-doped Co2Z ferrite has broad application prospects in multilayer filters and high-frequency antennas.