Synthesis and properties of ferrite nanopowders for epoxy-barium hexaferrite-nanocarbon composites for microwave applications

The effect of the synthesis conditions (type of chemical reagents, temperature of treatment) on phase composition and morphology of ferrite nanopowders containing barium hexaferrite was investigated. X-ray diffraction studies confirm the presence of two phases in synthesized powders - Fe₂O₃ and BaFe₁₂O₁₉ (BaM) - and ratio between these phases depends on the temperature of powder treatment at last stage of the synthesis. Electron microscopy studies showed that prepared ferrite powders consist of hexagonal particles having 20-50 nm thickness and 80-400 nm diameter, with exact values depending on the synthesis parameters. Measurements of magnetic susceptibility in the temperature range 300-850 K as well as the ferromagnetic resonance study confirm the presence of two phases in the prepared ferrite powders and correlate with the X-ray diffraction data. It was found that the addition of conductive carbon nanotubes or graphite nanoplatelets into the hybrid epoxy-barium hexaferrite composites allows to control the parts of absorbed and reflected microwave electromagnetic radiation in these composites.