Nanocomposite YCrO_3/Al_2O_3: Characterization of the Core?Shell, Magnetic Properties, and Enhancement of Dielectric Properties

摘要

Multifuncionality in polycrystalline multiferroic ceramics can be improved using an advanced synthesis process. In this work, core?shell design is being proposed to enhance the transport properties of biferroic YCrO_3. The atomic layer deposition (ALD) thin-film growth technique was used for the YCrO_3/Al_2O_3 (Y@Al) nanocomposite fabrication. A continuous, amorphous, and uniform Al_2O_3 shell, a few nanometers thick, was obtained and characterized by X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy. The transport properties of biferroic YCrO_3 coated with 50, 500, and 1000 ALD cycles of insulating Al_2O_3 were investigated using magnetization and AC conductivity measurements. It is observed that the values of the magnetic coercive field and the magnetization are affected by the amorphous and partially crystallized Al_2O_3 shell. Additionally, the Y@Al nanocomposite experiments show a notorious decreasing in the loss tangent and the electrical conductivity. Accordingly, hysteresis loops in the polarization versus electric energy data confirm the decrease of the leakage current as a consequence of the Al_2O_3 shell acting as a barrier layer. The results shown here confirm that the core?shell architecture is a promising alternative for improvement of the magnetic and ferroelectric properties in bulk multiferroics.