Synthesis, Characterization, and Optimization of Magnetoelectric BaTiO3-Iron Oxide Core-Shell Nanoparticles

Abstract

Improvement of magnetic, electronic, optical, and catalytic properties in cutting-edge technologies including drug delivery, energy storage, magnetic transistor, and spintronics requires novel nanomaterials. This article discusses the unique, clean, and homogeneous physiochemical synthesis of BaTiO₃/iron oxide core-shell nanoparticles with interfaces between ferroelectric and ferromagnetic materials. High-resolution transmission electron microscopy displayed the distinguished disparity between the core and shell of the synthesized nanoparticles. Elemental mapping and line scan confirmed the formation of the core-shell structure. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy detected the surface iron oxide phase as maghemite. Rietveld analysis of the X-ray diffraction data labeled the crystallinity and phase purity. This study provides a promising platform for the desirable property development of the futuristic multifunctional nanodevices.

Keywords: core–shell; energy-dispersive X-ray spectroscopy; magnetic iron-oxides; nanoparticles; oxide-nanomaterials synthesis; perovskite oxide; superparamagnetism.

Figure 1

Schematic illustration of the synthesis of perovskite oxide/ferrite core–shell nanostructures.

Figure 2

Elemental distributions in core–shell nanoparticles (CSNP) via TEM color map show (a) sample area for high-angle annular dark-field (HAADF) imaging. Elemental mapping of (b) only Ba atoms, (c) only Fe atoms, and (d) both Fe and Ba atoms.

Figure 3

(a) TEM-EDX showing Fe and Ba intensities at the region of interest for the quantitative analysis (yellow line) and (b) normalized intensity along the yellow line.

Figure 4

XRD diffraction data of oxidized CSNP that were synthesized from low (s1) and high (s2) initial concentration of FeCl₃·6H₂O. (a) Bragg peak from crystalline BaTiO₃, references were shifted in vertical scale, (b) zoomed in near (220) peak of maghemite, and (c) zoomed in near (311) peak of maghemite.

Figure 5

(a) Background-subtracted XPS scan of the BaTiO₃/iron oxide CSNP. (b) Sherley background-subtracted high-resolution scan data of the Fe 2p^3/2 orbital deconvoluted without surface peaks.

Figure 6

Field dependence of magnetization for the CSNP at (a) 300 K and (b) 5 K. Inset in the figure shows the low field fragment of the hysteresis loop. Scaling of the vertical axis is different (micro vs. milli) in (a) and (b).