Enhancement of microwave absorption properties of crystal-engineered perovskite oxide using cobalt ferrite

A multiferroic composite that comprises of a non-ferromagnetic ferroelectric material with a high dielectric constant and a non-ferroelectric ferromagnetic material with a high magnetostriction is of tremendous interest as microwave absorption material due to its applicability in tunable microwave phase shifters, resonators, filters, absorbers, etc. In the previous work, the solid solution of strontium titanate and sodium bismuth titanate (Sr${}_{0.5}$(Na${}_{0.5}$Bi${}_{0.5}$)${}_{0.5}$TiO${}_3$, SNBT50), which is observed to possess a very high dielectric constant at room temperature (Ferroelectrics, Vol 583, 252-263 [2021]), is successfully reported. Thus, in this work, a core-shell magnetoelectric composite is prepared by coating highly ferromagnetic and magnetostrictive cobalt ferrite onto a diamagnetic but strongly ferroelectric SNBT50 to enhance its magnetic properties and to investigate the modification in microwave absorption. Detailed characterization of electric and magnetic parameters in microwave frequency range (1-20 GHz) reports substantial enhancement in the magnetic permeabilities as well as the magnetic loss of the composite system, as opposed to bare SNBT50. This results in improved impedance matching in the system and enhanced microwave absorption, with a minimum reflection loss (RL) of -20.19 dB and an increased effective absorption bandwidth of 4.56 GHz at a mere 2.7 mm absorber length. Consequently, in this investigation, a promising pathway is established for the development of multiferroic composites with favorable magnetoelectric coupling at room temperature that possesses wide absorption bandwidth and suitable RL, making them highly suitable for use in multiferroic-based microwave components. (© 2024 Wiley‐VCH GmbH)