Nanocomposite YCrO₃/Al₂O₃: Characterization of the Core–Shell, Magnetic Properties, and Enhancement of Dielectric Properties

Abstract

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 YCrO3. The atomic layer deposition (ALD) thin-film growth technique was used for the YCrO3/Al2O3 (Y@Al) nanocomposite fabrication. A continuous, amorphous, and uniform Al2O3 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 YCrO3 coated with 50, 500, and 1000 ALD cycles of insulating Al2O3 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 Al2O3 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 Al2O3 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.

YCrO3/Al2O3 Core‐Shell Design: The Effect of the Nanometric Al2O3‐Shell on Dielectric Properties

“…It was observed that the bulk sintered nanocomposite have similar features as those reported in Ref. . Thereby, henceforth and for simplicity, the nanocomposite pellets will be referred as pristine, 50, 500, and 1000 ALD‐cycles.…”

“…Each particle was coated with a nanometric layer of Al 2 O 3 using the atomic layer deposition (ALD) technique. The experimental procedure of the nanocomposite fabrication has been described in detail elsewhere . The microstructural characterization of the powders was performed using high‐resolution transmission electron microscopy.…”

“…Heterostructures, nano‐particles in ceramic matrices, core‐shell structures, and other innovative methods are currently being investigated . In this regard, the core‐shell array seems to be a good alternative to improve the dielectric properties . Even new properties could arise in a nano‐compound, that were not present in its single phase.…”

Enhanced ionic conductivity in magnetron-sputtered Ce0.8Sm0.2O2-δ/Al2O3 multilayers

“…Slight changes in the intensity of peak (111) and peak (200) were observed which present a clear dependence on the number of interface. It indicates that amorphous AO layers might have impacts on the growth of SDC near the interface possibly due to strong interfacial interactions between the oxides [35,37]. The average crystalline sizes of SDC were calculated using Scherrer's formula and plotted in Fig.…”

Temperature dependent X‐ray diffraction and Raman spectroscopy studies of polycrystalline YCrO3 ceramics across the TC ~ 460 K

“…Raman spectroscopy being a local probe can provide a better insight to enquire the local distortion compared with neutron or XRD. Whereas most of the above experiments suggest that YCO is a RT ferroelectric, there are no reports of a well saturated P‐E loop for this system . Therefore, it is indeed an intriguing question that even when the electrical leakage is low, why YCO is a poor ferroelectric at RT.…”