Electromagnetic properties of La-Co substituted Zn<inf>2</inf>Y type hexagonal ferrite for microwave device applications

Abstract

In the recent decade, ferrites which possess low losses, good permeability, and permittivity, has been proposed as materials for microwave device applications. In this article, La-Co substituted Ba 2−x La x Zn 2 Fe 12-x Co x O 22 (Zn 2 Y-type) hexagonal ferrite was synthesized through conventional solid state reaction route with composition; x equals to 0.0, 0.1, 0.3 and 0.5. The phase formation behavior and changes in crystal structure parameters of the ferrite with substitution were investigated using X-ray diffraction (XRD) analysis. Accurate lattice parameters were evaluated through Rietveld refinement of XRD pattern. The XRD, as well as SEM-EDS analysis, showed that there was the formation of lanthanum iron oxide phase at the grain boundary of the ferrite phase. The densities of the substituted ferrites were lower than the pure ferrite due to the formation of La-ferrite phase. The microstructural analysis showed the decrease in grain growth with an increase in the substitution. Both the permittivity and permeability were decreased with the substitution due to the decreased densification. In substituted ferrite, both the permittivity and permeability were in the range 11 to 18 and they were stable in the frequency range 1 to 500 MHz. The ferrites with x = 0.1 and 0.3 composition reveal to be very promising candidates for the design of antennas with good impedance matching to free space and miniaturization factor. A ferrite antenna was designed and antenna parameters were simulated.