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

Abstract Fe 2 O 3 nanoparticles (NPs) coated by the SiO 2 shell with a thickness up to ˜6.5 nm were synthesized by a fast and facile microwave irradiation approach. The thickness of the SiO 2 shell around Fe 2 O 3 NPs could be controlled by varying tetraethoxysilane (TEOS) concentration as well as avoiding individual SiO 2 particle formation. The synthesized Fe 2 O 3 @SiO 2 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 Fe 2 O 3 NPs and Si O Si asymmetric stretching vibrational band at 1101 cm −1 in the prepared NCs obtained by FE-SEM and FT-IR study, respectively anticipated the successful SiO 2 coating on Fe 2 O 3 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 Fe 2 O 3 and pure SiO 2 NPs corroborated the formation of Fe O Si bond at the interface of Fe 2 O 3 (core) and SiO 2 (shell). The existence of magnetic property in the prepared NCs, even above the Curie temperature of Fe 2 O 3 , 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.