Magneto-dielectric characterization of TiO 2 -CoFe 2 O 4 derived ceramic composites

Dielectric permittivity (?), magnetic permeability (µ) and dielectric and magnetic loss (tan ?? and tan ?µ, respectively) of magneto-dielectric cobalt ferrite-titania (CFO-TO) ceramic composites are determined from 200 to 300 MHz. The four different combinations of phases - that can be produced in the sintered composite, according to the starting CFO/TO molar ratio - allow to tune the macroscopic permittivity and permeability. For the first time impedance, miniaturization and magneto-dielectric loss of the four classes of composites are calculated and discussed. The displayed miniaturization factors between 4.4 and 8.2 in the very-high frequency (VHF) range corroborate their potential application as magneto-dielectric substrate materials for antennas. Remarkably, the ceramic composites characterized by 2 vol.% and 3 vol.% of CFO and TO, respectively, dispersed in Fe2CoTi3O10 (FCTO) matrix display a magneto-dielectric loss lower than 0.07 and a miniaturization factor of 4.8.