Nanosized barium hexaferrite in novolac phenolic resin as microwave absorber for X-band application

Nanosized barium ferrite (BaFe12O19) with Novolac phenolic resin (NPR) is developed as a magnetic absorber for application in the frequency range 8.2–12.4 GHz. The absorption is studied by modifying the microstructural properties of the ferrite inclusion with annealing temperature and its content in the composite. Transmission electron microscopy and X-ray diffraction pattern confirms the formation of hexagonal structure of barium ferrite. The crystallite size of the barium ferrite particles is in nano-range and increases with annealing temperature. The BaFe12O19/NPR composite is prepared with different weight percentage of ferrite inclusions. The complex permittivity and complex permeability is measured at X-band and found to increase with annealing temperature and contents of ferrite inclusion. Theoretical study of reflection loss gives that 2 mm absorber samples are showing the best results for X-band application. Reflection loss measurement of the samples shows absorption peak of −24.61 dB at 10.26 GHz for 30 wt%, −28.39 dB at 9.98 GHz for 40 wt% and −37.06 dB at 9.5 GHz for 50 wt% of BaFe12O19 in NPR matrix. - Highlights: • BaFe12O19/NPR composite is developed as microwave absorbing material. • The maximal absorption is optimized with thickness using TLM. • Calculated reflection loss of 50 wt% for 2 mm thickness is 41.05 dB at 9.95 GHz. • Measured reflection loss of 50 wt% for 2 mm thickness is 37.06 dB at 9.5 GHz