Synthesis and Characterization of Rare Earth Metals Substituted Barium Hexaferrite Nanoparticles for Microwave Absorption Applications

Abstract

Sol-gel auto-combustion was used to successfully produce M-type barium hexagonal ferrite nanoparticles with La and Y co-substitution (BaYxLaxFe12-2xO19; 0.00 ≤ x ≤ 0.050). The production of a unique hexaferrite phase, with an average crystallite size spanning from 39 to 44 nm was confirmed by X-ray diffraction investigation. The fourier transformed infrared spectroscopy identified three distinct modes (between 400 - 650 cm1) which are consistent with the typical metal-oxygen bond vibrations at octahedral and tetrahedral sites. Morphological study has revealed that nanoparticles are uniformly scattered and have a spherical shape. Utilizing a vibrating sample magnetometer (VSM) to examine the magnetic characteristics, it was found that when La-Y substitution is increased, substitution is done on Octahedral side and not on Tetrahedral side as La and Y have large ionic radius. Net magnetic movement is decreased when La-Y substitution is increased. Measured using a vector network analyzer, the dielectric and magnetic properties showed an increase in dielectric and magnetic losses with increasing La-Y concentration, indicating improved energy dissipation capabilities. It was observed that the magnetic tangent losses in these nanoparticles were greater than the dielectric tangent losses, suggesting that magnetic losses predominate. With reflection loss values below -10 dB in the Ku band (12–18 GHz), which translates to approximately 90% absorption of incident microwaves, the samples showed strong microwave absorption. With x = 0.020, the maximum reflection loss of -23.75 dB was measured with a bandwidth of 5.62 GHz, demonstrating the materials' potential for use in microwave absorption applications.