Synthesis, structural and magnetic characterization of barium hexaferrites doped with La3+ and Co2+
Hexaferrites doped, nanoparticles, rare earth, chitosan, magnetic properties,
Hopkinson effect.
The barium hexaferrite, an iron oxide of hexagonal geometry, currently plays an important technological role in applications such as permanent magnets, microwave devices, and magnetic recording. In this work, we investigated the effects of doping with La3+ and Co2+ ions on the magnetic and structural properties of barium hexaferrite. Two series of samples were produced, Ba1-αLaαFe12-xCoxO19 with α=0.30, x=(0.0, 0.25, 0.50, 0.75, and 1.0) and α=0.10, x=(0.25 and 0.50). The samples were synthesized by the Ionic Coordination Reaction technique in chitosan polymer matrix and calcined in air 900 °C/4 h. The characterization was performed by X-ray diffractometry, scanning electron microscopy, vibrating sample magnetometry, Mössbauer spectroscopy and physical properties measurement system. The X-ray diffractograms revealed the presence of the BaFe12O19 type crystalline phase in all samples, with mean particle size ranging from 71 - 58 nm, decreasing with doping. The electron micrographs presented a particle morphology in the form of nanorods and nanoplates, with lengths and diameters varying around 190 nm and 70 nm, respectively. The analysis detected impurities of α-Fe2O3 and γ-Fe2O3, for the series with α=0.30.