Synthesis and characterization of BaFe12O19-CoFe2O4 ferrite composite for high-frequency antenna application

Abstract

Recently, ferrite composite ceramics have received much attention for high-frequency device applications as the composite has both dielectric and magnetic properties, good chemical stability, and high electrical resistivity. M-type hexagonal ferrite BaFe12O19 (BaM) and cubic spinel ferrite CoFe2O4 (CoF) composites; (BaM)1−x(CoF)x (x = 0.0, 0.25, 0.50, 0.75, and 1.0) were successfully synthesized by co-precipitation method. X-ray diffraction (XRD) analysis confirmed the formation of pure-phase BaM ferrite at 800 °C and CoF ferrite at 600 °C, respectively. The XRD analysis of composite ferrite showed the presence of both BaM and CoF ferrite phases in the composite. The composites were sintered at 1100 °C/4 h. The composite with x = 0.25 composition showed the most compact microstructure structure and higher bulk density compared to other composites. The composite (with x = 0.25) also showed the highest permittivity (~ 15), permeability (~ 13), and antenna miniaturization factor (~ 14) at 500 MHz due to mainly better densification. The permeability of composite was almost stable up to about 500 MHz. The coercivity was lowest in the composite with x = 0.25 composition indicating a change of hard magnetic behavior of BaM ferrite into a soft magnetic character after composite formation, which may be due to the formation of enlarged grain of BaM in the composite.