Microwave assisted rapid synthesis of Fe2O3@SiO2 core-shell nanocomposite for the persistence of magnetic property at high temperature

Abstract

Fe2O3 nanoparticles (NPs) coated by the SiO2 shell with a thickness up to ˜6.5 nm were synthesized by a fast and facile microwave irradiation approach. The thickness of the SiO2 shell around Fe2O3 NPs could be controlled by varying tetraethoxysilane (TEOS) concentration as well as avoiding individual SiO2 particle formation. The synthesized Fe2O3@SiO2 core-shell nanocomposites (NCs) were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) spectroscopy. The bigger particle size compared to the uncoated Fe2O3 NPs and SiOSi asymmetric stretching vibrational band at 1101 cm−1 in the prepared NCs obtained by FE-SEM and FT-IR study, respectively anticipated the successful SiO2 coating on Fe2O3 NPs. The presence of homogeneous silica layer was authenticated by TEM observation. The change in binding energy of Fe 2p3 and Si 2p in the synthesized NCs compared to the uncoated Fe2O3 and pure SiO2 NPs corroborated the formation of FeOSi bond at the interface of Fe2O3 (core) and SiO2 (shell). The existence of magnetic property in the prepared NCs, even above the Curie temperature of Fe2O3, was assured by vibrating sample magnetometer (VSM) study. This observation will undoubtedly inspire to design and fabricate novel heterostructures of iron oxide to retain its magnetization at high temperature.