Synthesis and Characterization of Co-Zr Substituted Strontium Hexaferrite Nanoparticles for Microwave Absorption Applications

Abstract

Co2+ -Zr4+ substituted M-type strontium hexagonal ferrite (SrCoxZrxFe12-2xO19) nanoparticles were successfully formed with various combinations (0.00 ≤ x ≤ 0.50) using sol-gel auto combustion process. The development of the distinct phase hexaferrite was confirmed by x-ray diffractograms displaying crystallite size between 28-35 nm. The fourier transformed infrared spectroscopy identified three distinct modes (between 400 - 650 cm-1 ), which are consistent in hexaferrites with the typical metal-oxygen bonds vibrations at tetrahedral and octahedral band positions. All the compositions exhibited a homogenous, consistently dispersed spherical shape without agglomeration. A declining trend was observed in the coercive field (Hc) with increasing content of Co-Zr substitution. On the contrary, the saturation magnetization (Ms) and remanence (Mr) values enhanced when the samples were subjected to vibrating sample magnetometer analysis. The vector network analyzer was employed to access the permittivity and permeability parameters. The examination disclosed a general increase in dielectric and magnetic losses with increasing Co-Zr contents, indicating enhanced energy dissipation behaviour. However, the values of magnetic tangent losses are higher than dielectric tangent losses, revealing that the magnetic loss nature is the primary loss mechanism for the synthesized nanoparticles. All the samples showed reflection loss (𝑅𝐿 ) below -10 dB, representing 90% absorption of incident microwaves. The max RL of value -33.42 dB was observed at 14.28 GHz for x = 0.35, revealing the potential candidacy of the synthesized compositions for microwave absorption applications.