Colloidal particles consisted of individual nanosized magnetite grains on the surface of the silica cores were obtained by two-stage sol-gel technique. Size distribution and microstructure of the particles were analyzed using atomic force microscopy, X-ray diffraction and Nitrogen thermal desorption. Magnetic properties of the particles were studied by the method of the longitudinal nonlinear response. It has been shown that nanoparticles of magnetite have a size corresponding to a superparamagnetic state but exhibit hysteresis properties. The phenomenon was explained using the magnetostatic interaction model based on the hypothesis of iron oxide particles cluster aggregation on the silica surface.
It was developed a new technique to assess micro- and mesopores with sizes below a few nanometers. The porous materials with hierarchical fractal-percolation structure were obtained with the sol-gel method. The tetraethoxysilane hydrolysis and polycondensation reactions were performed in the presence of salts as the sources of metal oxides. The porous materials were obtained under spinodal decomposition conditions during application of the polymer sol to the substrate surface and thermal treatment of the structures. The model is based on an enhanced Kepler net of the 4612 type with hexagonal cells filled with a quasi-two-dimensional projection of the Jullien fractal after the 2nd iteration. The materials obtained with the sol-gel method were studied using the atomic force microscopy, electron microscopy, thermal desorption, as well as an AutoCAD 2022 computer simulation of the percolation transition in a two-component system using the proposed multimodal model. Based on the results obtained, a new method was suggested to assess micro- and mesopores with sizes below a few nanometrs, which cannot be analyzed using the atomic force microscopy and electron microscopy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.