Co-substituted LiZnTiBi ferrite with equivalent permeability and permittivity for high-frequency miniaturized antenna application

In the present work, a Co-substituted LiZnTiBi (Li 0.43 Zn 0.27 Co x Ti 0.13 Fe 2.167-x Bi 0.003 O 4 ) ferrite with equivalent permeability and permittivity was prepared by a low-temperature sintering method. In detail, the LiZnTiBi ferrite with high permeability was obtained by a solid phase method. Next, different mass of Co 2 O 3 (x = 0.100, 0.125, 0.150, 0.175 and 0.200) were added to reduce permeability ( μ r ’ ) and enhance cut-off frequency ( f r ) of the ferrite. Results indicated that the Co-substituted LiZnTiBi ferrite with equivalent permeability and permittivity ( μ r ’  =  ε r ’  = ∼12.3) was obtained when additive amount of Co 2 O 3 (x) is around 0.150. Meanwhile, the cut-off frequency ( f r ) of the ferrite is more than 500 MHz. Also, the influences of Co 2 O 3 additive on the microstructure and phase structure of the LiZnTiBi ferrite have been investigated and discussed. SEM images indicated that the Co-substituted LiZnTiBi ferrites possess uniform and compact grains (average grain size is ∼1 μm). XRD patterns demonstrated that the LiZnTiBi ferrite material has a pure spinel structure. Rietveld refinement of XRD proved that Fe 3+ is substituted by Co 3+ . And energy dispersive spectrometer (EDS) result indicated that the Co element is existed in ferrite grains. Such a low-temperature sintering ferrite substrate material with equivalent permeability and permittivity at high frequency (@500 MHz) should also be an alternative material for microwave devices, especially for miniature antenna.