Enhanced Initial Permeability and Dielectric Constant in a Double‐ Percolating Ni_0.3Zn_0.7Fe_1.95O₄–Ni– Polymer Composite

Abstract A novel, three‐phase, double‐percolating composite with NiZn‐ferrite particles and nickel particles embedded in a poly(vinylidene fluoride) matrix is prepared by a simple hot‐pressing method. Large ferrite particles in the composite not only act as a magnetic phase, thus endowing the composite with a high initial permeability, but also present (in a high volume fraction) a discrete (non‐percolating) phase, confining polymer and metallic particles into a continuous double‐percolating structure of low volume fraction. In particular, a large enhancement in both the initial permeability and the dielectric constant of the three‐phase composites is observed, which is due mainly to the addition of a small number of nickel particles that act as both magnetic and percolative metallic phases. The dielectric and magnetic behavior observed in the three‐phase composites can be explained by effective‐medium and percolation theories.