Structural, dielectric, and magnetic properties of reduced graphene oxide-wrapped MnFe2O4 composites synthesized by in-situ sol-gel autocombustion method

Herein, the reduced graphene oxide (rGO) wrapped MnFe2O4 (MFO@rGO) composites with different rGO content of 10, 20, 30, and 40 wt% have been synthesized by a one-step in-situ sol-gel autocombustion method. The synthesized composites have been tested for their structural, electrical, dielectric, and magnetic characteristics. The composites are characterized by using standard techniques (XRD, HR-TEM, FTIR, and Raman spectroscopy). The composite having 20 wt% of rGO exhibits the highest value of dielectric constant (epsilon'similar to 1.32 x 10(4) at 100 Hz, epsilon'similar to 143 at 1 MHz) and dc conductivity (sigma(dc) = 4.31 x 10(-6) Omega(-1)-cm(-1)) among the investigated composites. The dipole polarization contribution to the dielectric relaxation behavior of MFO@rGO composites is observed, which arises from the increased vacancy defect dipoles in rGO sheets. The impedance studies show the existence of two different time relaxation phenomena in MFO@rGO composites. The magnetic measurements reveal the superparamagnetic behavior of composites. The saturation magnetization of composites decreases first with the increase in rGO content up to 20 wt% and then increases with a further increase in rGO content. The findings of this research make these composites a potential candidate for various applications such as EMI shielding and energy storage devices.

Automated summary

The MnFe2O4@rGO composite materials with different rGO contents were successfully synthesized using an in-situ sol-gel auto combustion method. Among them, the composite with 20wt% rGO exhibited the best dielectric performance and dc conductivity. The presence of vacancy defect dipoles in rGO sheets was observed to contribute to the dielectric relaxation behavior in the composites, making them potential candidates for various applications such as EMI shielding and energy storage devices.