Improved dielectric and magnetic properties of 1-3-type Ni _0.5Zn_0.5Fe₂O₄/epoxy composites for high-frequency applications

Ni_0.5Zn_0.5Fe₂O₄ (NZO)/epoxy composites with 1-3-type structure consisting of NZO rods in an epoxy matrix were fabricated by the dice and fill technique, with volume fraction from 40% to 70%. Improved frequency stability of the dielectric and magnetic properties was obtained in the frequency range from 10 MHz to 1 GHz. The optimized composite sample with 60% NZO rods in volume showed high dielectric and magnetic performance with permittivity between 9.2 and 10.3, dielectric loss between 0.09 and 0.25 in the frequency range from 50 MHz to 1 GHz, and permeability between 5.3 and 5.6, magnetic loss between 0.02 and 0.54 in the frequency range from 10 MHz to 1 GHz, respectively. Moreover, its permeability μ′ was increased to 170%, and the magnetic loss tan δ_μ was reduced to only 80% compared with the conventional 0-3-type composites with 40 vol% fillers at 1 GHz. The modelling and simulation results by Ansoft HFSS provided a reasonable explanation for the experimental results.