Co~(2+)Ti~(4+) substituted Z-type barium ferrite with enhanced imaginary permeability and resonance frequency

摘要

Co~(2+)Ti~(4+) substitution for Fe~(3+) in Co_2Z (Ba_3Co_2Fe_(24)O_(41)) has been prepared. The crystal structure and static and high-frequency magnetic properties have been studied for Ba_3Co_(2+x)Ti_xFe_(24-2x)O_(41) and the corresponding ferrite/polymer composites. As compared to the general Co_2Z ferrite/polymer composite, the CoTi substituted ferrite/polymer composite with x = 1.0 has a high natural resonance frequency (4.5 GHz), due to its large out-of-plane anisotropy fields H_θ. Furthermore, the maximum imaginary permeability μ″_(max) is increased by about 50%. The increase is attributed to a decreased damping coefficient, based on the curve-fitted results to the complex permeability spectra. The composites are good electromagnetic attenuation materials with low reflectivity and broad bandwidth at microwave frequencies.