Synthesis of Ferrite Nanoparticles and their Composites with Conductive Materials for Microwave Absorption Applications

Abstract

Our presented study is aimed at exploring the possible improvement of reflection losses displayed by M-type Ba-Sr hexaferrites with different ionic substitutions and addition of conductive fillers. Considering the excellent magnetic behavior of hexaferrite nanoparticles, three different series of Zr-Y, La-Co and Nd-Mn substituted Ba0.5Sr0.5Fe12O19 nanoparticles were investigated along with their composites with pristine Multiwall Carbon Nanotubes, Polyaniline and Polythiophene. X-ray Diffraction and Fourier Transformed Infrared Spectroscopy was carried out for all the samples, revealing the formation of corresponding phases and standard peaks of Me-O and Fe-O vibrational modes, respectively. For Zr-Y substituted Ba-Sr hexaferrite nanoparticles, the saturation magnetization and remanence initially increased, followed by a decrease with decreasing coercivity due to the weakening of exchange coupling. High frequency permittivity studies revealed the potential of our synthesized samples as microwave absorbers with the composition of x=0.35 exhibiting the maximum RL value of -32.27 dB at a matching frequency of 6.43 GHz. For La-Co substituted Ba-Sr hexaferrite nanoparticles, the calculated RL measurements revealed that all the samples can attenuate below −10 dB across various frequency bands. The maximum reflection loss of −30.57 dB was observed for x = 0.35 with matching thickness of 3 mm at 8.82 GHz in X-band. For Nd-Mn substituted hexaferrite nanoparticles, the permittivity and permeability measurements revealed suitable impedance matching, indicative of effective absorption properties. Additionally, the magnetic parameters were diminished due to altered exchange interactions between lattice sites, resulting in lowered values. Our synthesized samples demonstrated remarkable reflection losses, with the most significant reflection loss of -33dB recorded at 4.31 GHz for the sample composition of x=0.20 with experimental thickness of 3 mm. For ternary composite of Ba0.5Sr0.5Fe12O19 nanoparticles, MWCNTs and conductive polymer matrix, the microwave absorption of our samples was evaluated as a function of frequency and thickness, revealing its dependence on the quarter wavelength phenomenon with maximum reflection loss of −39 dB observed for ternary composite with Polythiophene matrix at 7.4 GHz resonance frequency. The resonance bands coincide with the operating frequency of military radars for shipborne and airborne surveillance and navigation in the X band. For ternary composite of xxvi Ba0.5Sr0.5Fe0.45Co0.5La0.05O19 nanoparticles, MWCNTs and polymers, the microwave absorption of our samples revealed their dependence on the quarter wavelength phenomenon, with maximum reflection loss of − 40.4 dB observed for ternary composite with Polythiophene matrix at 7.54 GHz resonance frequency. The study highlighted the potential of synthesized samples for electromagnetic signature reduction. For Ba0.5Sr0.5Fe0.45Mn0.5Nd0.05O19 nanoparticles, WMCNTs and conductive polymer matrix, magnetic hysteresis analysis demonstrated hard ferrimagnetic behavior, influenced by the addition of multi-walled carbon nanotubes (MWCNTs) and polymer matrices. Microwave absorption studies reveal enhanced permittivity and permeability, with the PANI matrix composite exhibiting the highest reflection loss (RL) of -46.58 dB at 4.87 GHz. For the study of nanocomposites of Zr-Y substituted hexaferrite nanoparticles, MWCNTs and conductive polymer matrix, X-ray diffraction (XRD) patterns reveal a magneto-plumbite hexagonal ferrite structure in synthesized samples, with efficient encapsulation of hexaferrite nanoparticles around MWCNTs. Magnetic hysteresis analysis shows a decrease in saturation magnetization and coercivity with the introduction of MWCNTs and polymers, attributing it to magnetic dilution. Microwave absorption studies demonstrate enhanced permittivity in nanocomposites, with the ternary composite achieving a remarkable reflection loss (RL) value of - 48.7 dB at 4.9 GHz. The synergy of hexaferrite, MWCNTs, and conductive polymers showcases potential for these composites as efficient microwave-absorbing materials in the 1-12 GHz frequency range. A systematic approach has been utilized to analyze the magnetic and electrical properties of synthesized hexaferrite nanoparticles with novel compositions. Such a detailed study can be helpful for future references regarding the usage of hexaferrites and their composites with conductive fillers for microwave absorption application in X-band. To our knowledge no one has reported such a comprehensive overview of such composite materials with multidimensional approach to discuss various parameters in the versatile stream of microwave absorption materials.