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

摘要

Low loss, flexible, polymer nanocomposites with improved magneto-dielectric properties at radio frequencies (RF) were successfully fabricated. Surfactant-modified nickel zinc iron oxide (NiZnFe_2O_4) nanoparticles with ferrimagnetic behavior at room temperature were synthesized by a seed-mediated growth method. The surfactant prevented NiZnFe _2O_4 particle aggregation and provided compatibility with [styrene-b-ethylene/butylene-b-styrene] block copolymer matrices. NiZnFe _2O_4/polymer composites were prepared by a solution-casting method. Experimental results showed that the dielectric permittivity (ε_r) and magnetic permeability (μ_r) of the polymer composite increased with increasing amount of NiZnFe_2O_4 doping. The dielectric loss (tanδ) was less than 0.010 at 1 GHz frequency. The increased miniaturization factor ((ε_rμ_r) ~(1/2)) and relative wave impedance ((μ_r/ε _r)~(1/2)) of the NiZnFe_2O_4 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.