Toroidal cores of MnxCo1−xFe2O4/PAA nanocomposites with potential applications in antennas

In this work, we study the electrical response of toroidal coils with cores of mixed ferrites magnetic nanoparticles (MNPs) embedded in a polyacrylamide matrix (MnxCo1−xFe2O4/PAA, 0 ≤ x ≤ 1). The MNPs were synthesized by thermal decomposition of molecular precursors and MnxCo1−xFe2O4/PAA toroidal cores were constructed by using the method of copolymerization of MNPs with acrylamide and bis-acrylamide. X-Ray Diffraction (XRD) patterns of MNPs correspond to the cubic spinel phase. The MNPs average size obtained by using Transmission Electron Microscopy (TEM) ranges from 6 to 12 nm. In order to compare our results we measure the characteristics of a commercial toroidal coil and we found that the impedance curves show a resonance peak for each configuration (commercial and Laboratory-made coils) around 75 MHz; the signal intensity of the Laboratory-made coil increases by one order of magnitude with respect to the commercial coil. We found that both, magnetic and electrical measurements, are related to the manganese concentration. The advantage of the designed MnxCo1−xFe2O4/PAA toroidal coils system lies in the fact that versatile combinations of Mn2+ and Co2+ components can bring facile tuning of the electrical and magnetic properties to optimize the impedance of the coils.