Two percolation behaviors in binary heterogeneous composites for high permittivity and negative permittivity

Abstract

Percolative composite is usually studied to achieve high permittivity when the fraction of fillers reaches the percolation threshold; besides, negative permittivity has also been a research hotspot and can be obtained above the percolation threshold. However, no studies have clarified whether the two percolation behaviors are the same one. Herein, the binary heterogeneous composites consisting of titanium nitride (TiN) particles and epoxy were prepared by compression molding, dielectric performance and percolation behavior were studied. Two percolation behaviors were demonstrated with increasing the TiN content. The first percolation behavior is to describe the high permittivity while the second one is to describe negative permittivity. It is interesting to find that the two percolation behaviors are actually associated with the competitive effect between inductance and capacitance. As a consequence, a high permittivity of 419 and a negative permittivity of -18 are obtained near the two percolation thresholds (42 % and 50 %), respectively. This work presents a clear physical description for the percolation phenomenon in the view of dielectric performance.

PANI/Zn‐Cu ferrite polymer composites as free‐standing high dielectric materials

“…This occurred as a result of the loading being increased further, which caused the permittivity to decrease with the volume percent of filler material. The low‐frequency plasma oscillation of free electrons in the continuous conductive distribution is responsible for this 74–77 . The main reason of the highest values of ε ′ at low frequencies is the accumulation of charges at the interfaces of different material constituents, which creates micro‐capacitance throughout the entire size of the material and contributes to an increase in ε ′ at low frequencies.…”

“…The low-frequency plasma oscillation of free electrons in the continuous conductive distribution is responsible for this. [74][75][76][77] The main reason of the highest values of ε 0 at low frequencies is the accumulation of charges at the interfaces of different material constituents, which creates micro-capacitance throughout the entire size of the material and contributes to an increase in ε 0 at low frequencies. In addition, it is noted that the dielectric constant ε 0 rises for the three different inorganic NPs (CuFe 2 O 4 , ZnFe 2 O 4 , and Cu 0.5 Zn 0.5 Fe 2 O 4 ) in a polymer matrix, because the relationships between inorganic NPs and the functional polar groups produce a dipole configuration.…”