Surfactant-modified nickel zinc iron oxide/polymer nanocomposites for radio frequency applications

Abstract

Low loss, flexible, polymer nanocomposites with improved magneto-dielectric properties at radio frequencies (RF) were successfully fabricated. Surfactant-modified nickel zinc iron oxide (NiZnFe2O4) nanoparticles with ferrimagnetic behavior at room temperature were synthesized by a seed-mediated growth method. The surfactant prevented NiZnFe2O4 particle aggregation and provided compatibility with [styrene-b-ethylene/butylene-b-styrene] block copolymer matrices. NiZnFe2O4/polymer composites were prepared by a solution-casting method. Experimental results showed that the dielectric permittivity (E >(r)) and magnetic permeability (mu(r)) of the polymer composite increased with increasing amount of NiZnFe2O4 doping. The dielectric loss (tan delta) was less than 0.010 at 1 GHz frequency. The increased miniaturization factor ((E >(r)mu(r))(1/2)) and relative wave impedance ((mu(r)/E >(r))(1/2)) of the NiZnFe2O4 nanocomposites could potentially lead to a reduced RF device's physical size with ease in impedance matching. Dynamic mechanical analysis (DMA) revealed that nanocomposites maintained 125% strain (elongation at break) with 30% nanoparticle doping.