Effect of PEO–PPO–PEO triblock copolymers in the synthesis of magnetic nanoparticles embedded in SiO 2 and TiO 2 matrices by sol–gel method

Hematite and maghemite nanoparticles embedded in silica and titanium dioxide matrices were obtained by sol–gel method. A mixture of precursor solutions of SiO 2 and TiO 2 doped with Fe 3 O 4 salt templated by the addition of PEO–PPO–PEO triblock copolymers in a concentration of 12.1 wt% PF127 (SiO 2 ) and 4.1 wt% P123 (TiO 2 ) produces very stable magnetic particles with average size between 5 and 10 nm. These neutral surfactants allow the control of the morphology and crystal phase of these magnetic nanoparticles, and stabilize the nanoparticles to avoid their aggregation. The samples were analyzed by X-ray diffraction, high-resolution transmission electron microscopy, and infrared and Mössbauer spectroscopies. Mössbauer results show that maghemite is the majority species in the SiO 2 matrix (61.3 %) and TiO 2 (63.0 %), respectively.