Low-loss percolative dielectric composite

Abstract

In this letter, we report a modified percolative polymer composite that has a low dielectric loss (tanδ∼0.02@10KHz, comparable to that of the polymer matrix), a high dielectric constant (k>100@10KHz, about 30 times higher than that of the polymer matrix), and a low frequency dependence. This high-k polymer hybrid is filled with self-passivated micro- and nano-aluminum particles. The self-passivation of an aluminum particle results in dense nanoscale insulating Al2O3 shells outside of the metallic spheres, which allows the electrons in the metallic core to tunnel through it, and thereby the aluminum/polymer composites exhibit a high dielectric constant as a percolation system; on the other hand, the insulating oxide layer restricts the electron transfer between aluminum particles, thus leading to a very low loss of the composites.

Electromagnetic Shielding Features in Lightweight PVDF-Aluminum Based Nanocomposites

“…Tanδ is, then, another important parameter in dielectric materials, which is caused by conductive loss of motion of charge carrier and/or dipole loss of dipole orientation polarization [34]. The tan δ and ε curves at room temperature of these samples as a function of frequency are shown in Figure 6.…”

Effect of Nano-ZrO2 on Properties of Room Temperature Vulcanization Phenyl Silicone Rubber

“…This phenomenon might be ascribed to the electrode polarization and the interface polarization between nanoparticles and phenyl silicone rubber phases as numerous interfaces occur with nanoparticles content increasing. The main factor influencing the resistivity of a composite is the interfacial interaction which produces energy barrier and blocks the transport of electrons [16]. In the case of treated ZrO 2 nanoparticles, tightly combined with the rubber matrix, and that causes a high transport barrier for electrons in terms of tunneling mechanism.…”

All-Ceramic Percolative Composites with a Colossal Dielectric Response

“…Very high dielectric constants can thus be achieved in metal-insulator composites close to the percolation point. However, up to now mainly organic percolative composites (Dang et al, 2003;Xu & Wong, 2005) and inorganic composites comprising metal particles dispersed in a dielectric matrix (Deepa et al, 2007;Grannan et al, 1981;Li et al, 2001;Yoshida, 1990) have been developed. In organic percolative composites values of the dielectric constant as high as 7000 were obtained .…”