Sol-Gel Synthesis, Structure, Morphology and Magnetic Properties of Ni0.6Mn0.4Fe2O4 Nanoparticles Embedded in SiO2 Matrix

The structure, morphology and magnetic properties of (Ni0.6Mn0.4Fe2O4)α(SiO2)100−α (α = 0–100%) nanocomposites (NCs) produced by sol-gel synthesis were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and vibrating sample magnetometry (VSM). At low calcination temperatures (300 °C), poorly crystallized Ni0.6Mn0.4Fe2O4, while at high calcination temperatures, well-crystallized Ni0.6Mn0.4Fe2O4 was obtained along with α-Fe2O3, quartz, cristobalite or iron silicate secondary phase, depending on the Ni0.6Mn0.4Fe2O4 content in the NCs. The average crystallite size increases from 2.6 to 74.5 nm with the increase of calcination temperature and ferrite content embedded in the SiO2 matrix. The saturation magnetization (Ms) enhances from 2.5 to 80.5 emu/g, the remanent magnetization (MR) from 0.68 to 12.6 emu/g and the coercive field (HC) from 126 to 260 Oe with increasing of Ni0.6Mn0.4Fe2O4 content in the NCs. The SiO2 matrix has a diamagnetic behavior with a minor ferromagnetic fraction, Ni0.6Mn0.4Fe2O4 embedded in SiO2 matrix displays superparamagnetic behavior, while unembedded Ni0.6Mn0.4Fe2O4 has a high-quality ferromagnetic behavior.

Review on Sol-Gel Synthesis of Perovskite and Oxide Nanomaterials

Sol-Gel is a low cost, well-established and flexible synthetic route to produce a wide range of micro- and nanostructures. Small variations in pH, temperature, precursors, time, pressure, atmosphere, among others, can lead to a wide family of compounds that share the same molecular structures. In this work, we present a general review of the synthesis of LaMnO3, SrTiO3, BaTiO3 perovskites and zinc vanadium oxides nanostructures based on Sol-Gel method. We discuss how small changes in the parameters of the synthesis can modify the morphology, shape, size, homogeneity, aggregation, among others, of the products. We also discuss the different precursors, solvents, working temperature, reaction times used throughout the synthesis. In the last section, we present novel uses of Sol-Gel with organic materials with emphasis on carbon-based compounds. All with a perspective to improve the method for future applications in different technological fields.