Enhancement of microwave absorption properties of bilayer absorber comprising of ZrB₂@SiO₂ composite and poly-ortho toluidine (PoTo) in 2–18 GHz frequency

In this work, ZrB₂@SiO₂ composite and Poly-ortho Toluidine (PoTo) was synthesized and the microwave absorption capability was investigated between 2 and 18 GHz frequencies. The XRD, FTIR and elemental mapping analysis confirm the presence and purity of the ZrB₂, SiO₂, ZrB₂@SiO₂ Composite and PoTo sample. An agglomerated morphology was observed especially in the PoTo sample. The high resolution XP spectra of SiO₂ and ZrB₂ shows their characteristic peaks which further support the finding of the XRD and FTIR analysis. The arrangement with PoTo as top layer having 0.5 mm thickness and ZrSi as bottom layer having 1.5 mm thickness gives a R_L of −29.8 at 5.2 GHz with bandwidth of effective absorption reaching about 4.4 GHz. A superior impedance matching between the ZrB₂@SiO₂ composite and PoTo sample may be the cause of the excellent microwave absorption capability. The value of the R_L indicate that the prepared sample could be used as efficient next generation microwave absorber material.