Achieving broad absorption bandwidth of Ba2Co2Fe12O22 ferrites by adjusting the sintering temperature

Abstract

The Ba2Co2Fe12O22 (Co2Y) ferrites were prepared via the sol–gel method, and the dielectric and magnetic properties were tuned by changing sintering temperature (Ta). It can be noted that the nature resonance frequency of Co2Y decreases form 10.2 GHz to 1.9 GHz with increasing sintering temperature, and the resonance peaks ascribed to exchange coupling between Fe2+ ions and Fe3+ ions appear in 13–17 GHz. Due to the synergy of Fe2+ ions and oxygen vacancies, the real part of complex permittivity (ε′) of Co2Y ferrites decreases firstly, and then increases with increasing sintering temperature. The excellent microwave absorption properties are obtained at Ta = 1100 °C, its effective absorption bandwidth (EAB) reaches 7.3 GHz at a thickness of only 1.4 mm. The outstanding properties are mainly ascribed to a combination of multiple reflections, dipole polarization, natural resonance, exchange resonance and good impedance matching. Our research provides an efficient approach for obtaining the thin and broadband microwave absorbers by adjusting the sintering temperature of Co2Y ferrites.