Mn-substituted Co2Z ferrite ceramics with impedance matching for ultra-high frequency miniaturization antennas

A series of Mn-substituted Z-type hexaferrite ceramics (Ba1.5Sr1.5Co2Fe(23-x)MnxO41; 0.0 <= x <= 0.5 at a step of 0.1) were prepared via double sintering method. According to EDS data, Mn3+ ions were uniformly distributed throughout the lattice. The relative densities of all samples were higher than 90%, enriching the maxima at x = 0.1 and x = 0.2 (above 95%), which indicated compact grain growth. The greatest saturation magnetization (56.18 emu/g) was achieved at x = 0.1 and then dropped with a further doping of Mn3+ ion, the coercivity showed the opposite trend. Moreover, both permeability and permittivity of the samples drastically changed with the increase of x. Particularly, the samples with x = 0.1-0.2 possessed close permeability (mu ') and permittivity (epsilon '), and they have relatively high miniaturization factors (nx=0.1 = 12.74, nx=0.2 = 10.38) in the frequency range 10 MHz to 1 GHz. Ba1.5Sr1.5Co2Fe22.9Mn0.1O41 ceramics exhibits best microwave properties, mu ' = 11.26, epsilon ' = 14.42, magnetic loss tangent tan delta mu = 0.048, dielectric loss tangent tan delta epsilon = 0.0024, and Snoek constant = 17.433 GHz. Consequently, these Mn-substituted hexaferrite ceramics with impedance matching have great application potential for ultra -high frequency miniaturized antenna substrates.