Electromagnetic wave absorption properties of multi-walled carbon nanotubes decorated with La-doped BaTiO3 nanocrystals synthesized by a solvothermal method

Ba1−xLaxTiO3/multi-walled carbon nanotube (MWCNT) nanocomposites with different concentrations of La3+ doping, were synthesized by a solvothermal process. The prepared nanocomposites had a hybrid microstructure in which Ba1−xLaxTiO3 nanocrystals with diameter of 10–30 nm were firmly immobilized on the MWCNTs sidewalls. Electromagnetic (EM) wave absorption properties of La-doped BaTiO3/MWCNT nanocomposites were investigated in the 7.5–18 GHz frequency range for an absorber thickness of 1 mm. The reflection loss (RL) calculated from the EM parameters of the samples, moved to low frequencies with increasing La3+ doping. The widest absorption bandwidth, with the lowest frequency range, was observed in a nanocomposite doped with 1.5 at% La3+. An RL exceeding −5 dB for this sample was obtained in the frequencies ranging from 9.6 to 16.3 GHz, with the optimal RL of −17.4 dB at 10.9 GHz, due to enhanced interfacial polarization resulting in developed image. In addition, the RL for the sample shifted to the low frequency region and the peaks became sharper in the 2–18 GHz frequency range with increasing absorber thickness. For BaTiO3/MWCNT nanocomposites, La3+ doping can greatly improve the EM wave absorbing ability in a thin absorber thickness and the donor-doped nanocomposites show promise for application in EM wave shielding materials with broad absorption bandwidths.