Electronic structure and magnetic and electromagnetic wave absorption properties of BaFe12-xCoxO19 M-type hexaferrites

Crystal, electronic structures and the magnetic and electromagnetic wave absorption properties of BaFe12- xCoxO19 (x=0–2) M-type hexaferrites prepared by a co-precipitation technique were studied. The analyses of Xray diffraction patterns indicated that the samples mainly crystallized in the P63/mmc hexagonal structure, with the additional constitution of Y-type hexaferrite as x > 0. The replacement of Co2+ for Fe3+ in BaFe12-xCoxO19 changed the lattice constants and caused lattice distortions. Particularly, Co2+ doping also reduced magnetization and hard magnetic property of BaFe12-xCoxO19. This is ascribed to magnetic moment of Co2+ smaller than that of Fe3+ and to the decrease of magnetocrystalline anisotropy. Having studied electromagnetic wave absorption properties in the frequency range f=0.1–18 GHz, we found BaFe12-xCoxO19 showing high reflection loss (RL) values at frequencies of 0.1–15 GHz, but fairly low RL values at higher frequencies. These features suggest that BaFe12-xCoxO19 can be suitable to electronic devices working at GHz frequencies.