Synthesis and characterization of low-loss Fe3O4-PDMS magneto-dielectric polymer nanocomposites for RF applications

This paper presents the methodologies for synthesis and characterization of a new class of low loss Fe
₃
O
₄
-PDMS polymer nanocomposites, which exhibits well-tailored magneto-dielectric properties. Single crystalline Fe
₃
O
₄
nanoparticles with a small size distribution of 7.5 ± 2nm were prepared by chemical precipitation method to retain the superparamagnetic characteristics and the Fe304-PDMS nanocomposites with uniformly dispersed Fe
₃
O
₄
nanoparticles at three different loading concentrations of 80 wt%, 50 wt%, and 30 wt% were explored. Room-temperature magnetization measurements were conducted for the plain Fe
₃
O
₄
nanoparticles and these Fe
₃
O
₄
-PDMS nanocomposites using a physical properties measurement system (PPMS) while extraction of microwave properties in wide range frequencies between 1GHz and 8GHz under different levels of externally applied magnetic field was performed by using a custom-built transmission line test fixture. The 80 wt% Fe
₃
O
₄
-PDMS nanocomposites under 0.37T of biasing field have exhibited coveted magneto-dielectric properties at 4GHz, by showing an equal-valued relative permittivity ε
_r
and relative permeability μ
_r
of 3.0. It is worthwhile mentioning that the peak relative permeability of 3.55 along with fairly low dielectric and magnetic loss tangents less than 0.02 were obtained under 0.2T DC biasing field. These newly-characterized Fe304-PDMS nanocomposites were used for successful implementation of miniaturized patch antennas, which is going to be reported subsequently.