Phase composition, magnetic properties and thermal behavior of a novel Fe2O3–SiO2 composite material

• An Fe2O3–SiO2 nanosized composite material was prepared in an aqueous medium.
• The magnetic properties of the material are controllable by synthesis conditions.
• Morphology of the material causes augmentation of the iron oxides thermal stability.

An Fe2O3–SiO2 composite was prepared by controllable Fe3+ and SIO32-hydrolysis. Scanning (SEM) and transmitting (TEM) electron microscopy images showed particles with an average size of 10–30 nm composed of an iron-containing core covered with a silica shell. The FT-IR, vibrating sample magnitometer (VSM), thermogravimetric analysis and Mössbauer spectroscopy study confirmed that the core consisted of ferrihydrite. Heating at 300 °C did not result in any noticeable phase transitions, whereas 800 °C heating caused the formation of the maghemite γ-Fe2O3 phase. Such improvement of the thermal stability of maghemite is promising for development of heat-resistant magnetic materials.