Synthesis and characterization of Ba₂Co₂Fe₁₂O₂₂–NiFe₂O₄ ferrite composites: a useful substrate material in miniaturizing antenna

Abstract

The manuscript describes the electro-magnetic characterization of Ba₂Co₂Fe₁₂O₂₂(Co₂Y) and NiFe₂O₄ ferrite composites synthesized by a one-step co-precipitation method. The composites of (Co₂Y)_1−x(NiFe₂O₄)_x with x = 0.0, 0.25, 0.50, 0.75, and 1.0 were prepared. The X-ray diffraction (XRD) analysis confirmed the formation of pure phase NiFe₂O₄ and Co₂Y ferrites after calcination at 600 and 1000 °C temperature, respectively. The XRD analysis showed two separate ferrite phases in the composite specimen, indicating the true nature of composite. The composites were sintered at 1200 °C for 4 h. The bulk density of x = 0.25 composition was the highest, and its microstructure was the most compact. The saturation magnetization, remanence magnetization, and coercivity of the composites increased with the increase in NiFe₂O₄ content. Among all the composites, x = 0.25 composition showed the highest permittivity and permeability due to its better densification and lower porosity. Permeability of all the composites was almost stable up to about 500 MHz. The AC conductivity and magnetic and dielectric losses were low up to about 500 MHz. A good miniaturization factor and matching impedance were shown by the composites, which would be useful as a substrate material in a miniaturizing antenna. The magnetic and dielectric properties suggest that the composite ferrite is a kind of magneto-dielectric material having potential for high-frequency applications.