Dielectric Properties and Electrical Percolation in MnFe2O4/Epoxy Resin Composites

Broadband dielectric properties of epoxy composites containing the different additions of manganese ferrite (MnFe2O4) with two spherical particle size (28 and 60 nm) have been studied in the wide temperature range from 150 K to 500 K. The percolation thresholds in such systems are 30 and 29.3 vol.% for small and large MnFe2O4 particles, respectively. The small difference in the percolation threshold value is related to a better distribution of larger nanoparticles. Composites above the percolation threshold are appropriate candidates for electromagnetic shielding applications. Above 380 K the electrical conductivity is typical for all composites, both below and above the percolation threshold due to the electrical transport in the polymer matrix. The activation energy strongly decreases with MnFe2O4 concentration indicating that the electrical transport occurs simultaneously in both MnFe2O4 and epoxy matrix subsystems