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

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 (er) and magnetic permeability (lr) of the polymer composite increased with increasing amount of NiZnFe2O4 doping. The dielectric loss (tand) was less than 0.010 at 1 GHz frequency. The increased miniaturization factor ((erlr) ) and relative wave impedance ((lr/er) ) 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.