Low-loss NiZnCo ferrite composites with tunable magneto-dielectric performances for high-frequency applications

Abstract

A series of Ni0.5Zn0.3Co0.2Fe2O4/epoxy magnetodielectric composites were synthesized through solvent-assisted method and demonstrate tunable permeability and permittivity, ultralow losses and high refractive index over a broad frequency region of the VHF and UHF bands. Experimental results reveal that the permeability μ' decreases from ~4.2 to ~3.5 while the permittivity ε' was improved from ~5.0 to ~6.1 with an increase in epoxy weight fraction from 1 to 20 wt%. These variations are shown to be intimately related to the microstructures in accordance with effective medium theory and magnetic circuit model. Correspondingly, the characteristic impedance of the magnetodielectric composite medium is varied from ~0.75 to ~0.90 while maintaining a refractive index around 4.5. Typical magnetic loss as tan δμ and dielectric loss as tan δε at 0.5 GHz are as low as in the order of 10−2 and 10−3, respectively. These magnetodielectric materials provide excellent radio frequency results that allowing for the realization of the high-performance miniaturized electronic devices, systems, and platforms.