Electromagnetic interference (EMI) shielding, microwave absorption, and optical sensing properties of BaM/CCTO composites in Ku-band

Sol-gel autocombustion technique was used to synthesized composites of barium hexaferrites (BaM) and calcium copper titanate (CCTO) with chemical composition Ba1−xCoxFe12−x−yDyxLayO19 (x = 0.0, 0.1, 0.2, 0.3 and y = 0.0, 0.4, 0.5, 0.6) and Ca1-xErxCu3Ti4−yMnyO12 (x = 0.0, 0.1, 0.2, 0.3 and y = 0.0, 0.4, 0.5, 0.6) respectively. The BaM/CCTO composites exhibit a single crystalline phases of both BaM and CCTO, this observation is supported by Raman spectroscopy. Characteristics peaks of both BaM and CCTO were observed at 439 and 592 cm−1; these peaks give a hint on the formation of both BaM and CCTO phase in the composites. Morphology analysis show that the grains of the BaM nanoparticles exhibit uneven distribution with morphology close to hexagonal structure while the CCTO microparticles shows cubic-like grains with homogenous distribution and the stoichiometry of the prepared composites was also observed. Lattice fringes of BaM nanoparticles and CCTO microparticles with sizes of 0.2629 and 0.2613 nm corresponding to (1 1 4) and (2 2 0) hkl planes respectively have been observed. The observed band-gap increases with increase in crystallite size. The coercivity increases as a result of the presence of CCTO phase. BaMCCTO4 composite shows maximum reflection loss (RL) of −27.9 dB (99.83% absorption) at 16.5 GHz and matching thickness of 3 mm with effective absorption (RL 20 dB) bandwidth of 4.2 GHz. Keywords: Permittivity, Permeability, Reflection loss, Shielding effectiveness, Band gap