Electromagnetic performance, optical and physiochemical features of CaTiO₃/NiO and SrFe₁₂O₁₉/NiO nanocomposites based...

Herein, two distinct nanocomposites of CaTiO₃ micro-cubes and polygonal SrFe₁₂O₁₉, both decorated with NiO nanoparticles, were successfully synthesized using hydrothermal method. The physico-chemical features of as-prepared samples were evaluated via XRD, FTIR, UV-vis, BET, XPS, FESEM and EDS analysis. Microwave attenuation features of as-prepared single layer absorbers were determined by VNA analysis in 2-18 GHz. Simulation confirmation was checked by preparing a bi-layer samples and evaluating it using VNA analysis after finding the appropriate thickness of each layer. The reflection loss from each single layer samples containing 20 wt% of each CaTiO₃/NiO and SrFe₁₂O₁₉/NiO nanocomposites were -16 dB and -35 dB at 6.3 GHz with 2.5 mm matching thickness respectively. However, the RL was -34 dB at 10 GHz frequency with 2 mm thickness in a bilayer absorber with SrFe₁₂O₁₉/NiO nanocomposite layer put as absorbing layer with 1 mm thickness and CaTiO₃/NiO positioned as matching layer with 1 mm thickness. Furthermore, at the X-band frequency, approximately entire band absorption is obtained. The findings demonstrate that adjusting the order and thickness of the layers in a bilayer absorber may readily improve microwave absorption performance. By comparing the results of simulation with real prepared bilayer absorbers, we found that with a 2 mm overall thickness, the bi-layer absorbers display accurate RL values, but not the matching frequency monitored in the simulation process. In reality, this discrepancy was unavoidable.