Cactus-like double-shell structured SiO 2 @TiO 2 microspheres: Fabrication, electrorheological performances and microwave absorption

The cactus-like double-shell structured SiO2@TiO2 microspheres (CDS SiO2@TiO2 microspheres) with high dielectric properties were successfully fabricated and utilized as high-performance electrorheological (ER) fluids and microwave absorbing materials. The SiO2 nanospheres with average diameters of 190 nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), and used as the core for the first coating layer of TiO2 achieved by sol-gel method. The final cactus-like TiO2 layer was prepared via a hydrothermal method. The morphology of the resultant samples was characterized via transmission electron microscopy (TEM), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). This novel CDS SiO2@TiO2 microspheres based suspension exhibited improved ER properties compared to conventional bare SiO2 spheres.